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81. THE RACE FOR AUTONOMOUS ELECTRIC VEHICLES                             

The California Department of Motor Vehicles (DMV) proposed today a new set of rules that will govern the operation of autonomous vehicles on the state's roads. Simultaneously, Google announced that it was spinning off its self-driving car unit into a standalone business setting up the stage for a fleet of self-driving taxis that will compete head-to-head with Uber, which itself is investing heavily in self-driving vehicles. Tesla, GM, Mercedes Benz, Ford and several others have not been shy in the media, all announcing efforts and prototypes towards autonomous driving. 

The Google (or perhaps more aptly under its new name of Alphabet) pod-like self-driving vehicles are powered by batteries, so it is fair to say that it is only a matter of time before electric powertrains  become the foundation for this new vision of autonomous cars. The race is early, still very early, but the stakes are potentially immense. 

One of the early metrics of a race worth gauging is each player's present IP position. It is not a simple question to answer but one can glean some insight -- autonomous electric vehicles are very sophisticated systems using complex components, so one would expect that intellectual property will play a central role both in the development of this market segment as well as eventual litigation among the participants.

The next two charts show the extent of the present IP position for a select number of companies. The chart on the left shows the number of US patents issued since 2000 covering two categories: i) battery technology including battery battery materials, manufacturing and battery management systems, and ii) technologies related to designing and building electric vehicles. For the time being, I will focus this post on the "electric" portion of this race, addressing the battery and electric systems for these vehicles -- leaving autonomous driving for others to discuss. I assume that the number of issued US patents will reflect within reason the amount of know-how a company possesses in battery and EV technologies. 

The first observation that stands out is the large number of US patents that Toyota has secured in both areas of batteries and electric vehicle systems. They eclipse the number of patents issued to Tesla and GM. Honda and Ford, two companies that have been relatively quiet in the media, are clearly building their foundations. The German automakers, judging from their US patent portfolio, seem to be lagging -- though this should not be misinterpreted as losing or lagging in the race. Apple has not yet publicly announced that it plans to build cars, but rumors abound in this respect and as such, the companies is categorized with the automakers. Their portfolio, however, is heavily biased towards battery technology, courtesy of their prowess in consumer devices. 

Automakers rely heavily on suppliers of components and subsystems. Among the well-established ones, Robert Bosch stands out with a sizable bag of issued US patents covering both batteries and electrical vehicles. Samsung and LG, two large suppliers of electronic components to the Korean car makers, have a strong IP position in building batteries owing to their respective battery divisions, SDI and LG Chem -- but there is not much evidence of strong IP in electrical powertrain and electric vehicles. It is also surprising to see Delphi and Johnson Controls lagging in both categories -- could this mean that the automakers are choosing to own and control key technologies instead of outsourcing them to their traditional supply chain partners? Time will tell. 

In this evolving race and ambitious vision for the future, these statistics are merely just perturbations for the time being. However, given enough time, they could amplify and influence the outcome of who will win and who will not. Stay tuned!

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

80. HOVER BOARDS CHALLENGING BATTERY SAFETY                                                       

What do Chappaqua, NY and Brentwood, CA have in common? Burning hoverboards....this is a new category of battery-powered levitating boards, sort of electrically-powered, self-balanced skateboards. In both cases, the fires and ensuing explosion were attributed to the lithium-ion battery. Amazon has discontinued the sale of such devices. So what is happening?

I will leave the particulars of each incident to investigative authorities. Instead, I will address the potential failure points of such systems -- and how their designs, or perhaps lack thereof, put the safety of consumers at risk.

Back in the early 2000s, laptops suffered from many recalls because of battery safety issues. Two major sources of problems were identified: i) the quality of the battery design and manufacturing, and ii) operation of the battery under unsafe conditions. The battery & PC industries, under the weight of costly recalls, reacted and implemented rigid processes to ensure the safety of their products. The major Li+ battery manufacturers, in particular Sony Energy, LG Chem, Samsung SDI, implemented extensive safety design features in the cells themselves, as well as exhaustive test procedures to ensure the safety of the battery under a wide range of conditions -- for example, batteries today are designed to withstand a sharp object piercing it (this has become a common test today). In parallel, electronic circuitry with advanced safety features were added alongside. This circuitry ensured that corner conditions, such as excessive voltage or excessive current or even excessive temperature conditions triggered a safe shutdown and isolating the battery from the rest of the electrical systems. The result today is that the vast majority of consumer devices follow stringent safety rules and are by-and-large very safe.

A hoverboard, in contrast, has a much larger lithium-ion battery than any of other consumer electronics. Most smartphones have batteries with capacities in the range of 8 to 15 W.h. Laptops and tablets have capacities in the range of 30 to 80 W.h. A hoverboard's battery has a capacity of 150 to 200 W.h. This is a lot of energy that can cause serious damage if not operated properly and safely. 

There are no known standards yet for hoverboard batteries but judging from the offerings on Internet stores, the battery pack seems to consist of a stack of 11s and 2p (22 cells in total), totaling a nominal voltage of 36V and charge capacity rating of 4,400 mAh. That means that each cell has a rating of 2,200 mAh, and is most likely a cylindrical 18650. These types of cells have become commoditized (they were used in PCs some 10 years ago) and are made in China often by low-tier manufacturers. I estimate the cost to be in the range of $15 to $25 for the entire pack. They sell on eBay for about $75 each. Several of them carry a Samsung label -- I would not be surprised if they are all fraudulently made in China.

So how can these batteries be unsafe? Many factors come into consideration. First, 18650 cylindrical cells, especially with lower capacity ratings (2 to 2.5Ah) are virtually all made in China, many in factories that lack the quality control and safety measures that their Japanese and Korean counterparts learned the hard way 10 to 15 years ago. Second, the operation of the hoverboard requires relatively large currents (typically 3 to 6 A). Wirings, solder junctions, and battery contact points all become potential failure points if not designed properly. Thermal design in such tight volumes becomes paramount -- leading potentially to fatiguing of the wirings and connectors. In a nutshell, when several such considerations lack in the design and manufacture of the product (as is commonly the case with products coming out of China), the outcome is quite unsafe leading to fires, explosion and possibly loss of life.

So before you run out a buy yourself or  your family a hoverboard for the holidays, do yourself a favor, complete your diligence to ensure that the product has gone through stringent qualification tests and procedures.


© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

79. CAN I FAST-CHARGE MY TESLA OR EV?                                                     

Before I start this post, I encourage all new readers to go back to the early posts if they desire to learn more about the basics of lithium-ion batteries and their operation.

This post is dedicated to deciphering the growing complexity of charging stations for plug-in hybrid and pure electric vehicles (xEVs), especially as their popularity grows among drivers. 

The charging of xEVs, whether at your home or at dedicated charging stations, is usually governed by a set of standards agreed upon by a vast number of contributing organizations, such as the automakers, electric utilities, component makers and many others. Several organizations including SAE International, ANSI and IEEE have led the  coordination and development of such standards -- they are numerous -- covering, for instance, the types and interoperability of connector designs and charging power levels (SAE J1772), communication and signaling protocols  (SAE J2931/1) between the xEV and the charging station (also known as EV supply equipment -- EVSE), wireless charging (SAE J2954) as well as many others related to diagnostics, safety, DC charging...etc. Today's post addresses charging from the perspective of the SAE J1772 standard and its competing standard CHAdeMO.

So let's start with understanding what charging levels are and how they are defined by the various standards. There are 4 levels of charging:  two levels using conventional AC charging, and two additional levels using higher-voltage DC  charging. They are summarized in the next table:

Let's start with AC levels 1 and 2. Level 1 is what you get using the charging cord supplied to you by the car maker if you own an xEV. It plugs into the standard 120V household outlet and delivers, in theory 1.7kW. Some of you are probably tempted to multiply 120V by 20A and realize that's more than 1.7kW...if you are that person, remember that this is an AC current, so you need to multiply by 0.707. This is the maximum power delivered to the connector plugged into the car. It is not the power delivered to the battery. The battery's power is delivered by an on-board battery management system (on-board charger) that has to convert the voltage to a level appropriate for the battery. In reality, the car battery receives a best-case power of about 1.2 - 1.3kW to account for the electrical efficiency of the system -- taking an average consumption of 250Wh per mile, that is equivalent to about 5 to 6 miles for each hour of charging...ouch!

Reality is a little worse than that: standard household power plugs are limited to 15A (instead of 20A) thereby decreasing the power delivered to the battery to a measly 900W. At this power level, a Nissan Leaf's battery (nominal 24kWh / effective 20kWh) takes 22 hours to fully charge. Yikes! Now one can begin to understand why xEV owners do not line up near a Level 1 charger...but it does get crowded at a Level 2 charger.

AC Level 2 uses a 240V single-phase mains. The lowest current level is 20A corresponding to a maximum power (again at the output of the connector) of 3.4kW. The typical public charging stations, such as the ones managed by ChargePoint, provide 6.7kW. However, there is a catch. The on-board charging circuitry in your xEV must be able to use that power. Early Nissan Leaf models had 3.3kW-circuitry -- in other words, regardless of the maximum power at the charging station, the maximum power the car is willing to accept is 3.3kW.  Newer xEV models, e.g., Nissan Leaf, Ford Focus Electric, Chevy Volt, have on-board chargers capable of up to 6.6kW. Again, this means if the charging station were to provide 19.2kW, your car cannot accept more than 6.6kW...this is by far the most common charging level as dictated by the presently deployed infrastructure. It equates to about 25 miles for each hour of charging. Once again, using the Nissan Leaf as an example, its battery will fully charge in 3.5 hours with a Level 2 charger (6.6kW). That's not fast charging, but it sure is a heck-of-a-lot faster than Level 1.

Fast charging with DC gets more complex because there are competing approaches. Of course, we are also now talking about insanely high power levels, and consequently very expensive charging stations  and associated installation costs ($50,000 to $100,000 each).

SAE has the J1772 Combo DC standard. CHAdeMO has another competing standard. Tesla has its own proprietary fast-charging using their network of Superchargers (though not DC). But what they have in common is that they all seek to provide high power levels to the vehicle...up to 120kW. This infrastructure is still relatively scarce -- Tesla is the only one aggressively deploying fast charging Superchargers along specially designated highway corridors.

Naturally, charging a car battery at such high power levels begs a new series of questions on whether this creates any significant and permanent damage to the battery. The brief answer is: YES, damage does occur...but super fast charging is so rare that no one is really paying attention to this question, at least not for now. Besides, with the exception of Tesla, your average xEV cannot charge faster than 6.7kW, so having a fast charging station is a moot point. 

A final word on fast charging the Tesla batteries. At 120kW of input power, this equates to a charging rate of 120/85 = 1.4C -- this is guaranteed to cause serious damage to your Tesla battery if you were to charge on a regular basis. But then again, if Elon Musk and Tesla Motors are willing to cover you under their warranty, do you really care?

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

78.  THREE DISCOVERIES THAT REVOLUTIONIZED Li+ BATTERIES          

For those of you old enough to remember the Sony Walkman portable radios in 1970s, they ushered a new era of consumer electronics, and one could argue, the first mobile battery-powered "devices," the ancestral precursor to the Apple iPod three decades later. These early electronics were powered by replaceable batteries. Lithium-ion batteries didn't exist back then. So how did they get invented?

A large amount of research and development effort has gone and continues to pour into rechargeable batteries, but one could point to three seminal moments that transformed rechargeable batteries in general, and lithium-ion batteries in particular.

The first moment was in the early 1970s at Exxon. It was a time when large corporations such as GE, Exxon, IBM and others competed with AT&T's famed Bell Labs for scientific supremacy....a time not much different than ours today with the likes of Google and Apple competing for new innovations. An English-born chemist at Exxon's research laboratories, Stanley Wittingham, made an important scientific discovery; he found that ions can "intercalate" in between sheets (or layers) of titanium  sulfide, and effectively store electrical charge. By shuttling these ions back and forth between two electrodes with such layered materials, he could build a rechargeable battery. Exxon filed for its first battery patent in 1976, and was awarded a US patent 4,084,046 in 1978.

But Exxon and Wittingham ran into several challenges: the batteries degraded fast and they were prone to explode. Exxon couldn't capitalize on this discovery.

The second seminal moment came from John Goodenough, now professor emeritus at UT Austin, but at the time, he was a professor of Chemistry at Oxford University in the UK. After researching metal oxides and testing several varieties, he and his group discovered that lithium-cobalt-oxide (LCO) was a very effective cathode material. The results were published in 1980: the battery had a higher voltage than Wittingham's cell (2.2 volts); its energy density was far better than anything on the market; it worked very well at room temperature. It was the missing link to making a rechargeable battery.

Someone had to turn these discoveries into a product; that role was exceptionally fulfilled by Sony in 1991. Sony combined Goodenough's LCO cathode with a graphite/carbon anode to produce its first commercially available rechargeable lithium-ion battery. Sony put these new batteries into their camcorders and cameras...it was a commercial success. Sony went on to rule lithium-ion batteries for a decade or more. Sony continues to date to be one of the major producers of lithium-ion batteries, albeit several other companies have since emerged as even larger suppliers.

The Sony commercialization was also a major catalyst for laboratories around the world to accelerate the material discovery. John Goodenough's team at UT Austin went on to discover another category of cathode material, lithium-iron-phosphate (LFP), that was safer than LCO but at the expense of lower energy density.

This post is by no-means intended to give all the inventive credit to the three groups mentioned above. Hundreds if not thousands of innovators and organizations have greatly contributed to the evolution of the lithium-ion battery and continue to do so. Much like the semiconductor industry points to a handful discoveries that transformed electronics, one can trace similar inflection points in the history of the lithium-ion battery.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

77. THE FINANCIAL DILEMMA OF BATTERY MANUFACTURERS                           

The lithium-ion battery market is large. For consumer devices, it will exceed $10B in 2015 corresponding to a total output capacity of 40 GWh. The promise of even greater markets in stationary energy storage and electric vehicles is attracting interest and investment. Goldman Sachs estimates that the energy storage market could reach a demand greater than 700 GWh in 2015, eclipsing the expected 175 GWh capacity demand for electric vehicles.

But these large market figures belie the harsh market realities of building batteries, in particular manufacturing cells for lithium-ion applications. This post will dive a little deeper into the financial challenges that cell manufacturers are facing today and will most likely face as the battery markets expand rapidly in the coming years.

Let's start by looking at the present state of cell manufacturers. The bulk of the manufactured cells goes to fulfill the demand in consumer devices, including some 1.4B smartphones and 400+ million laptops and tablets. To first order, 4 major cell suppliers deliver 80% or more of these cells, mostly polymer cells. 

The $10 Billion-battery consumer market is serviced primarily by 4 large Asia-based suppliers.

By virtue of the market size and volume, batteries for consumer devices have been and continue to be under immense pricing pressures. On average, the pricing is about $0.25 per Wh, but that can be as low as $0.10 per Wh for some of the vintage low energy density batteries. This competitive landscape left these battery suppliers with, let's just say, less-than-attractive financial statements. For example, a visit to LG Chem's website reveals the financial situation for their "energy division." For this most recent 3rd quarter in 2015, it recorded revenues of approximately $640m, about 80-85% of it from consumer devices, and the rest from their sale into xEVs (Electric and hybrid electric vehicles). Against these revenues, the company recorded a meager profit of 1.3%. It had reported a 6% loss in the prior quarter. Gross margins for battery manufacturers tend to be in the range of 10 - 20% at best. That's nothing to write home about.

Such strained financials seldom give the company's management any latitude to invest in extensive R&D -- the expectation of future returns on invested R&D is often missing in such scenarios. The result is diminishing innovation, rising pricing pressures, and the onslaught -- more rapid than one might imagine -- of new low-cost manufacturers, especially ones based in China. 

Instead, the management teams of battery manufacturing companies begin to look at alternative markets that can be financially more rewarding. After all, they are all watching Panasonic reap the rewards of their relationship with Tesla. Panasonic recorded nearly $800m of sales to Tesla in 2014, and the markets expect the number will grow to $3.35B in 2020 if and when Tesla succeeds in shipping 250,000 electric vehicles. 

We can witness this change of direction from a number of observations. First, Nikkei published on 28 October a report that Tesla is in discussions to source batteries from LG Chem, in addition to Panasonic. Second, let's take a look at Samsung SDI's revenue projections for their battery division.

One can immediately see flat revenues from their mobile product line, but growing projected sales from energy storage as well as transportation. In other words, the unstated strategy of these giant conglomerates is to controllably relinquish their mobile market share to their Chinese competitors and focus on winning in the growing but hopefully more profitable storage and xEV markets. In these markets, there is also room for them to add value beyond building cells -- they can also build packs and the complex battery management systems.

So where does this leave innovation in consumer devices? most likely stranded! Increasing pricing pressures from Chinese manufacturers makes it quite unattractive to invest in consumer batteries -- thus leaving the mobile device OEMs at the mercy of decreasing cell quality and possibly performance.  Of course, I am sure someone will argue why can't the innovation trickle down from energy storage and xEVs to consumer? The answer is that these are complex systems where innovation is often at the system-level and less so at the cell-level where consumer devices demand it. Additionally, the cost points for these large-scale systems are vastly different from the relatively simpler consumer device; hence the dilemma that is creeping up rapidly on both battery manufacturers and consumer device OEMs. This is also the commoditization of the lithium-ion battery.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

76. WOULD 007 DRIVE AN ELECTRIC CAR ?                                                            

Ah, we could talk for hours about James Bond's 1964 Aston Martin DB5.  Aston Martin remains an iconic luxury brand, one of the last vestiges of British automotive style. So fast forward to 2015, the age of electric cars and Teslas: Aston Martin just announced its plan for the RapidE, a fully electric Aston Martin 1000-hp luxury sports car that the company's CEO sees as an "intrinsic part of the company's future product portfolio." I wonder how soon will James Bond get to drive this new beauty?

...that is if he does not decide to drive a Tesla P90D instead. At nearly 760 hp, this all-electric luxury sports car has broken every 0-60 mph speed record. Of course, Tesla Motors has also changed our communal perspective of electric vehicles which have reached a record 1,000,000 vehicles on US roads this past September. 

Porsche, the iconic German luxury sports car maker, will not be outdone by Tesla nor Aston Martin. The company, now part of Volkswagen recently caught with polluting diesel engines, is planning an all-electric vehicle, aptly named the Porsche E. The concept is stunningly beautiful. Yes, electric cars are here to stay -- and you might never know, they could become the new "green" cars to replace the disgraced diesel autos.

The all-electric Porsche E concept. Source: Porsche

But these luxury cars are for the 1%! What's there for the other 99%? This space is looking more promising, especially as we begin to see new announcements that combine aesthetics with longer driving range and increasing affordability. 

Tesla has made several announcements about its Model 3 planned for a first public showing in March 2016. With a supposed range of 200 miles, it is targeted at a relatively more affordable price around $35,000 to $40,000. Chevrolet is also betting more than a few dollars on increased adoption of electric vehicles. It just announced its plans to release the Bolt in 2017 with a projected range of 200 miles too. Chevrolet made another pleasant announcement: it sees its own cost of lithium-ion batteries dropping to or below $100 per kWh by 2022. That is at least ⅓ or ¼ the cost level of just a couple of years back. Read this earlier post on trends in battery costs.

The Chevy Volt, first announced in 2009, is getting ready for the release of an all new 2016 model that sees an expansion in the capacity of its battery, longer driving range and a lower price point. True, the Volt is not an all-electric -- it carries a gas-powered generator -- but the evolution of its battery represents a serious push to make electric and/or hybrid electric more affordable for the general population.

These new announcements highlight two accelerating trends in the industry: i) increasing driving range to the 200-mi level, and ii) decreasing battery costs. The combination of these will serve to make electric cars competitive v.s. traditional combustion-engine vehicles. Yes, this will continue to be a relatively slow process -- especially when compared to the evolutionary speeds of consumer devices -- but the trend is unmistakable, electric cars are here to stay; lithium-ion batteries will witness wider deployment and adoption; and no major material breakthroughs are necessary to meet these goals for the coming years.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

75. LET'S TALK ABOUT ENERGY DENSITY                                                 

Pause for a second and wonder why electric vehicles have frustratingly limited driving ranges? or why your smartphone lasts only for a few limited hours instead of an entire month? Yet, a good ol' combustion-engine car can go for hundreds of miles without a problem. This is the manifestation of energy density. Let's talk about it in more detail and hopefully give the reader a bit of more intuitive sense on the importance of this metric.

Energy density, as the title implies, is a measure of how much energy is stored in a certain volume. A battery or a gas tank has a certain limited volume, therefore it is important to have a metric that relates to how much energy can be stored in that volume. Obviously, energy is what powers our smartphones or vehicles, therefore energy density is a metric that describes how far one can drive  or use a device given the limited amount of energy stored in the "tank."

The following table compares a select number of energy-storing materials or mechanisms, all the way from the traditional lead-acid battery (the type that you will find under your hood) to much more sophisticated energy sources such as nuclear fission. So what is this table telling us?

The first nine rows are all batteries, or devices that can store electrical energy. Batteries are either primary (i.e., non-rechargeable) or secondary (fancy term for rechargeable). The last three rows are widely used energy sources in our society today and are used here for comparison purposes: Ethanol and gasoline are examples of carbon-based fuels, and the last row, well, we all know what nuclear power can do, both the good and the evil.

The first observation: Even the best battery, the absolute best, has 10X lower energy density that carbon-based fuels. That means the same tank (or equivalently sized battery) will let you drive 10X more miles using carbon-based fuels. I cheated a little here -- electric systems are more efficient than carbon-fuel systems, so the difference is more like 3X rather than 10X, but that will be left to another discussion.

The second observation: The difference between the best battery and worst battery (in terms of energy density) is substantial, also about a factor of 10X. Lead-acid batteries, discovered over a 150 years ago, don't provide a lot of energy density. NiCd batteries also leave a lot to desire. Do you remember the bulky batteries in the early cell phones back in the 1990s? Or just google the GM EV1, the first electric vehicle from GM that used lead acid batteries.

But...there is always a but: While NiCd have for the most part disappeared, lead acids are incredibly inexpensive, and they survive. Until the day comes when the price point of alternative batteries drops radically, lead acids will continue to be the king of batteries in applications where energy density is not critical -- i.e., where it is ok to occupy a larger volume, for example backup systems for cell phone towers.

The third observation: Energy density increased by a factor of 10X over 150 years! That's not terribly promising unless the future brings forth some serious breakthroughs in materials. Is there anything on the horizon? There is a lot of promising good material research, but when one takes into account cost, cycle life, and other constraints such as manufacturing and capital, it is very hard to point to one particular technology that is likely to be commercialized in the next 5 years. So the wait and the hope continue.

The fourth observation: Lithium-ion technologies, first commercialized by Sony in 1991, encompass a wide range of energy densities depending on the particular choice of material for the electrodes. Lithium-ion batteries using nickel-cobalt-aluminum oxide (NCA) electrodes -- the type used in the Tesla Model S -- have over 3X the energy density of lithium-ion batteries with lithium iron-phosphate  (LFP) electrodes. So why is anyone considering LFP lithium-ion batteries: Cycle life! Welcome to the world of compromises.

So by now, you are probably disappointed about the future of batteries! It is true that the progress of batteries over the last 150 years has been slow, and it is true that batteries can't yet compete with carbon-based fuels...but that does not mean that the incremental progress in batteries is insufficient to meet many needs of our society. Yes, they can be better, but present batteries boasting 700 Wh/l can and are sufficient to provide an electric vehicle with a range of 300 miles. In other words, don't expect miracles in batteries, but do expect that incremental technologies from materials to algorithms and electronics will be sufficient to address a wide range of energy storage needs, including smartphones that can last an honest day to electric vehicles with a range of 200 - 300 miles.

There is plenty to look forward to here, just be careful about wild claims of amazing discoveries. If there are too good to be true, then there is a probably a good reason to be skeptical.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

74. QNOVO QNS and QUALCOMM'S QUICK CHARGE 3.0                              

There were several releases in the last day covering fast charging, and in particular, Qualcomm's evolution of its power delivery mechanism called Quick Charge 3.0. This is quite exciting because it elevates the power delivery -- i.e., the circuitry that delivers the high current from the wall socket to your smartphone -- to a new level of efficiency.  Why does it matter? Two operative words: HEAT and COST. An explanation follows.

Fast charging a smartphone entails delivering somewhere between 15 and 20 Watts to the mobile device from the AC adapter at the wall socket. This is about 3 or 4 times the power delivered by the standard 5-Watts AC adapter. So even a small inefficiency -- technical jargon for a loss of power along the way -- can now result in serious overheating of the smartphone. Qualcomm's QC 3.0 cleverly negotiates the proper power voltage across the USB cable to minimize these losses. Secondly, building AC adapters that can deliver 20 Watts can become very expensive, that is unless the voltage is raised. This is similar to why overhead transmission lines from the utility companies operate at high voltages. Kudos to Qualcomm for leading the pack here on higher-voltage power delivery protocols.

Qnovo announced in parallel with Qualcomm our companion software adaptive charging product called Qnovo QNS. A snippet of the announcement is below. What does it mean?

The primary question with fast charging the battery is what happens to the health of the battery? QC 3.0 addresses bringing the power to the terminals of the battery. QNS complements QC 3.0 to ensure that the battery health is maintained. In other words, by combining QC 3.0 and Qnovo QNS, one can fast charge AND rest that the battery life and health will not be compromised.  Qualcomm QC 3.0 deals primarily with the power segment between the wall socket and the terminals of the battery. Qnovo QNS deals with "how" this power is inserted into the battery. Together, QC 3.0 and QNS are designed to interface with each other without any hiccups, and complement each other in an end-to-end solution optimized for the smartphone OEMs.

Can one use one of these two technologies without the other? sure, a smartphone OEM has that option, but it is the combination of the two products that gives the smartphone OEM and the end consumer the desired benefit: that is fast charging and long battery life and health. Why compromise?

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

73. LITHIUM PLATING IS IMMENSELY HAZARDOUS                                   

One of the serious consequences of fast charging lithium-ion batteries is the formation of lithium metal on the surface of the anode (the negative electrode when the battery is being charged). While the battery industry has invested significant effort to ensure the mechanical integrity of the battery and avoid unintended fires in case of mechanical damage, the formation of lithium plating during fast charging is a new challenge to battery vendors. Some battery manufacturers take it very seriously, whereas others tend to me more lax if not somewhat cavalier about its risks.

Let's be clear about...Lithium metal plating inside the battery creates extremely hazardous conditions that may lead to fires or even exploding batteries.  Lithium plating leads to the formation of lithium metal deposits on the surface of the graphite (carbon) anode. These islands tend to grow over tend, both across the surface area and in the thickness forming dendritic-like structures. If they pierce (and they can) the separator -- the porous plastic layer between the two electrodes -- then an electrical short-circuit occurs leading to excessive heating and potential fires (in battery parlance, it is politely known as thermal runaway).

For the most part of the history of the lithium-ion battery, lithium plating was not a major concern. Well designed batteries ensured that they stayed away from the precursor conditions to lithium plating. Some battery manufacturers implemented additional safety measures -- such as special surface coatings -- that are intended to reduce the risk of a dendritic short-circuit. But with advent of high energy density cells and the rapid deployment of fast charging, the batteries are often operating near dangerous conditions. And some battery manufacturers seem to intentionally skirt the problem as it is not visible during daily operation -- that is until a fire occurs and the damage is done.

The next photograph shows the anode surface of a dissected polymer lithium-ion cell -- in fact, two identical cells, one charged at a slow charge rate (left side), and at a higher charge rate (right side). The cells were cycled 100 times before cut open and observed.

On the left side, the surface of the graphite anode is pristine. On the right side, bright stripes of lithium metal are apparent on the edges. That's where lithium metal tends to start forming -- the current density on the edges tend to be higher (concentrated electric field lines) thus presenting favorable conditions for the formation of lithium metal. Additionally, manufacturing defects are more likely to be present on the edges, also presenting "seeds" for plating.  As the cell is further cycled (and aged), the lithium plating propagates and covers more of the anode surface, creating increased risks of a catastrophic failure.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

72. LET'S TALK ABOUT THE WAIST                                                               

Not yours, of course....the smartphone's waist. We see a race among the smartphone makers to go thin. The iPhone 6 Plus is 6.9 mm thick and it is already been outflanked by some new devices coming from China. In particular, the Oppo R5 boasts a thickness of only 4.85 mm, and the Vivo X5 Max is an even thinner 4.75 mm. So what determines how thin one can go?

Naturally, the mechanics of the device are clearly one limiting factor...nobody wants their smartphone to "bend." For the most part, manufacturers are now using hardened aluminum cases for added resistance to bending. With the exception of some early complaints about the iPhone 6 Plus, there have been no credible reports of additional bending failures. Another limiting factor is the touch screen. There have been some great innovation here, most of it related to fusing the touch glass with the display, thereby reducing the touchscreen thickness. For example, the AMOLED screen on the Vivo X5 Max is only 1.35 mm thick.

So that leaves the battery as the last frontier...why am I not surprised? The battery seems to consistently win the title of bottleneck, and this is the topic of today's discussion. Why can't we make batteries ultra thin?

The answer is actually "yes, we can." Batteries can be made really thin, I mean thinner than you might imagine, sub 1 mm. But naturally, there are tradeoffs. The first tradeoff is that thinner batteries cannot boast the same energy density than their thicker counterparts -- there is just too much "electrical overhead" (e.g., connectors, plates) that they become dominant when the battery is too thin. See this earlier post that shows the impact of thickness on energy density. For a smartphone device, somewhere around 3 mm is the lower limit of battery thickness. Some smartphone makers instead choose to go thick just to provide more battery capacity -- the most recent example is the Moto X whose thickness is a whopping 11 mm, more than double Oppo's thickness !!!! So the first tradeoff is battery capacity vs. stylishness. Judging from the market trends, stylishness seems to be winning for now.

There is also a second and very important tradeoff, and that relates to swelling. I described in a very early post what happens to the battery as it ages...it bloats, and consequently becomes unsafe. This "swelling" phenomenon, through which the battery physically grows, has two components. They are shown in the next chart.

This chart shows the actual and measured thickness of a 3-Ah cell used in the LG G2 smartphone. It is a polymer cell and is embedded (i.e., non-removable) inside the mobile device. The thickness is measured over 60 cycles of charging and discharging. One readily observes two separate trends, almost like a yoyo on an escalator:

• One trend is a fast variation in thickness with a known periodicity of one cycle (this is the yoyo effect). The thickness varies by about 0.15 mm, or approximately 3% of the cell's thickness but is a fully reversible effect. This is due to the physical expansion of the graphite anode. During charging, lithium ions intercalate (fancy language for "insert themselves") inside the carbon-graphite material (also known as matrix) thereby pushing the carbon atoms aside and causing physical growth. During discharge, the opposite happens and the anode returns to a thinner state.

• The second trend is a slow, semi-linear growth in thickness (this is the escalator effect). This is related to irreversible damage to the graphite anode -- as the lithium ions go in and out of the anode, they leave just a tiny bit of damage that accumulates over time into this irreversible thickening of the anode (and consequently of the cell). As one can immediately observe, this second trend is significantly larger in magnitude than the first trend. For this cell made by LG Chem, the increase in thickness over 60 cycles is 0.15 mm, or 3% of the original thickness. Typically, over 500 cycles, this may reach 8 or even 10%.

As a result, manufacturers of smartphones need to make an allowance inside the device for the battery cell to grow in time -- this allowance is somewhere between 10 and 15% of the cell's thickness, or up to 0.7 mm; quite a significant number. Failing to provide this allowance risks placing large pressures on the touchscreen and cracking it.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

71.  IS THERE ENOUGH LITHIUM ?                                                                                                    

Elon Musks' Gigafactory comes on line in 2017 to build some 35 GWh annually worth of batteries for Tesla. Thirty-five giga....that sounds like a big number. But wait, thirty-five gigabytes is a small capacity for your disk drive. So let's put things in perspective in this post.

Tesla's Gigafactory should be capable of producing by 2020 enough battery packs for some 500,000 electric vehicles. That corresponds to a capacity of about 75,000 kWh for each vehicle, with each pack including about 7,000 individual 18650 cells -- see this earlier post on the battery pack of a Tesla S. Quick math reveals that the annual output of the Gigafactory equals a little less than 4 billion 18650 cells annually.  The annual worldwide production of lithium-ion batteries stood in 2014 just around 35 GWh, which means that Tesla intends to effectively double the global production -- and this is only for making 500,000 cars. So this begs the question, will there be enough lithium to make all, and I mean all, cars on the road electric? Let's explore.

First, let's estimate the total usage requirement of lithium. An individual state-of-the-art 3-Ah 18650 cell weighs about 48 g, and contains on average a mere 2 g of lithium. The lithium is in a salt form suspended in a solvent (the electrolyte) or embedded in the cathode material, often a composite metal oxide of lithium (such as lithium cobalt oxide).  Therefore 35 GWh, or equivalently 4 billion 18650 cells, consume 7,900 metric tons of lithium. 

But wait, lithium does not exist naturally in a metallic form -- remember, lithium metal is reactive. Lithium is mined in the form of lithium carbonate; by weight, it is 5.2x heavier than lithium. In other words, the demand in 2014 corresponds to 41,000 tons LCE (in the lingo of the mining industry, LCE stands for lithium carbonate equivalent to account for other forms of mined lithium salts such as lithium hydroxides). With a selling price of $8,000 per ton (and rising), one can readily see that lithium mining for batteries only is a $320m annual business growing at 7-8% per year. That's a pretty decent figure but it pales compared to the market size of other metal commodities such as copper. It's worth noting here that lithium is used for several other applications such as glass manufacturing. In 2014, the total worldwide demand for lithium exceeded 100,000 tons LCE. The vast majority of presently operating lithium mines are in South America, in particular Chile's Atacama salt flat and Bolivia. Increasingly, deposits in China and Canada, for example the Whabouchi field in northern Quebec, are being explored for further mining as demand and prices for lithium increase.

I still haven't answered the key question: is there enough of it? Lithium is a very light element and is fairly abundant in the Earth crust -- light elements formed early during the evolution of the Sun. The USGS estimates its abundance at 500 atoms per million atoms of Silicon (the most abundant element in the upper Earth crust), or about 0.05%. By comparison, it is as abundant as zinc and copper, and a million times more abundant than gold. We never questioned whether there is enough gold in the world, did we?

There have been no accurate studies to estimate the world reserves of lithium. SQM, the world's largest lithium mining company, estimates that the world reserves stand near 100 to 300 million tons LCE, or equivalent to 2,400x the demand that the Gigafactory is expected to generate. 

So the brief answer is: don't worry, there is plenty of lithium. If you are a speculative investor, it may be a good time to buy land in Chile or Bolivia, at least what SQM and other mining companies haven't bought yet. You see, 007 didn't get it right in Quantum of Solace. The coup d'etat should have been to corner Bolivia's lithium salt mines, not its water supply.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

70.  REVIVING A DEAD BATTERY, REALLY?                                                                 

A statement of this devilish nature during the middle ages would have earned its author a burning at the stake. The mere notion of a "battery" would have probably been in the realm of druids and witches, and reviving anything dead would have been...well, enough said, it is the 21st century.

I will digress today a little and talk about your average primary (i.e., non-rechargeable) battery, the type that Energizer, Duracell, and their competitors sell billions of every year, all of which wind up in the trash bin or recycling centers -- excepting the batteries that sit on one's desk for ages as if somehow they will disappear on their own. How do these batteries die, and when they do, are they really dead? Let's explore.

For the purpose of this discussion, let's focus on Alkaline batteries. The typical ones, like AA or AAA, are nominally rated at 1.5 V. In other words, when they are fresh and unused, one would measure 1.5 V at the battery terminals. As the battery is inserted into a gadget and gets used, the voltage at the terminals drops, and fast it does. As the voltage drops, it reaches a point where it is no longer sufficient to power the electronics in the gadget. Often, these gadgets, such as toys, employ inexpensive electronics. This means that these electronics do not employ the most modern electronics circuitry. This is parlance for electronics that are not low-voltage and low-power. In other words, these inexpensive electronics draw more current than they need to, and they operate at higher voltages than they should -- all in the spirit of saving costs. But these operating requirements place a bigger burden on the battery, the result of which the battery's voltage drains rapidly and meets an early death.

It should be apparent to the reader that the end of the battery -- its "death" --  is now defined as the time at which its terminal voltage is no longer able to power the electronics. This is somewhat subjective because that clearly depends on the quality and sophistication of the electronics in your gadget. Usually, many inexpensive electronics begin to stop operating somewhere between 1.2 V and 1.35 V. Very rarely, one may see electronics get lower in operating voltages but such gadgets would most likely be associated with higher price points, and could very well just use an embedded lithium-ion battery to project an image of a "good" product.

Looking at the Energizer E91 specification sheet, one immediately can observe that this battery has a life of less than 2 hours to hit 1.3 V, and 3 hours to hit 1.2 V (assuming a discharge current of 250 mA). At this point, the electronics begin to stop operating; the cheap display on your child's toy begins to fade, and voila, you pronounce the battery dead and discard it.

But wait! Is it really true that the battery is dead? Again, it is a matter of definition. For a helpless parent trying to appease a screaming child, the battery is DEAD. But to some engineers and entrepreneurs, they will be quick to observe that this battery continues to hold a lot of charge and energy. Looking at the voltage chart above for the E91, the area under the red curve is the amount of "energy" that the battery holds. So it becomes immediately clear that if the battery is declared dead at 1.2 V, it continues to hold about 75% of its original energy. This is a lot!

So the magic question becomes how to access this extra energy well? and how to do so in a cost-effective and reliable manner? This is where I will put a plug for the company Batteroo Inc.. The team figured out an elegant solution to put a very thin reusable sleeve around the presumed dead battery with low-power electronics that will "boost and regulate" the raw terminal voltage of the battery back up to a higher voltage, say 1.5 V, sufficient now to operate a gadget. This has an effect of reviving this "dead" battery and substantially extending its life. I love clever and simple ideas! Batteroo's challenge is now to fight off the battery vendors who will not be pleased with selling fewer batteries.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

69.  INSIDE THE BATTERY OF A NISSAN LEAF                                                         

One of the most recognizable electric vehicles on the road, the Nissan Leaf, has a battery capacity of 24 kWh. It has a rated driving range of nearly 80 miles, about ⅓ that of the Tesla Model S. It is therefore not surprising that its battery capacity is also nearly ⅓ that of the Tesla's battery which I covered earlier in this post. Today's post, with the help of some publicly available information, sheds some light on what powers the Nissan Leaf.

The battery in the Nissan Leaf is manufactured and assembled by the Automotive Energy Supply Corporation (AESC), a joint venture corporation between Nissan and NEC located just outside of Yokohama, Japan. Until Tesla's Gigafactory comes on line, AESC's factory remains the largest automotive battery manufacturer shipping nearly 90,000 batteries annually, mostly into the Nissan and Renault EVs and hybrids.

AESC discloses on its website some pertinent details about the battery and its characteristics. A teardown of the Leaf battery pack by Ben Nelson at 300mpg.org supplements this post with a nice step-by-step mechanical disassembly of this pack.  The weight of the Nissan Leaf pack checks in at 648-lb, about ½ that of the Tesla's pack, yet only ⅓ its capacity. I will revisit this point below.

The first photograph shows the pack with its top protective metal case removed. The pack measures approximately 1570.5 x 1188 x 264.9 mm (61.8 x 46.8 x 10.4 in). 

Photograph of the battery pack for a Nissan Leaf electric vehicle. One can readily see some of the smaller modules that make up the pack. Courtesy: Benjamin Nelson.

The first observation we make is that the pack consists of smaller modules. In fact, AESC tells us that there are 48 of them, each measuring about 303 x 223 x 55 mm (11.93 x 8.78 x 1.38 in) and weighing about 3.8 kg (8.4 lb). These modules are arranged into three distinct sections, one near the back with 24 modules bolted to each other in a vertical position, and two other sections on each side of the pack, each with 12 modules in a horizontal position. Electrically, the modules are all connected in series. Bus bars (thick copper connectors) electrically connect together these three distinct sections.

Each module is made of four individual pouch (also known as laminate) cells, each cell like the one shown in the next photograph. The four cells are electrically configured as 2 in series and 2 in parallel. This prior post teaches more about series and parallel configurations.

Photograph of the battery pouch cell used in the Nissan Leaf pack. Source: AESC

AESC shares some of the electrical characteristics of the cell. Each cell is rated at 32.5 Ah, or about 10X that of the 18650 cell used in the Tesla. It uses a different material for the cathode called lithium-manganese-oxide with nickel oxide (LiMn2O4 with LiNiO2) that is inherently safer than the lithium-cobalt-oxide cathode material used in mobile devices and the Tesla pack. The cell's voltage chart shows a maximum cell voltage of 4.2V. Rated nominally at 3.75V, one pouch cell can store a maximum 122 Wh of energy, or about 10 times what an iPhone 6 Plus battery can store.

So let's do some math. Each module contains 4 cells, so that's a total energy of 488 Wh. This is now a substantial amount and hence one should exert plenty of caution in handling or using such modules. The nominal voltage across one module is 2x3.75 = 7.5V, and the nominal voltage across the entire Leaf pack is 48x7.5 = 360V. The maximum voltage at the pack is 2x4.2x48 = 403V, though it is widely known that the Leaf only uses about 80% of the pack's capacity (20 kWh out of the 24 kWh to preserve cycle life) making the maximum cell voltage closer to 4.0V, and the pack's maximum voltage closer to 384V. 

The voltage chart above shows that one cell can deliver at least 90A of current. That's equivalent to a pack delivering more than 180A at 384V, or 70+ kW (95+ hp) of power to the drivetrain. This estimate is not far off from the Leaf's vehicle rating of 90 kW (120 hp). In any case, one can see that both current and voltage values are high, warranting special design measures to ensure safety. 

But for the added safety of the LMnO material, Nissan incurs some important penalties. First, the intrinsic energy density of the individual pouch is only about 320 Wh/L. Compare this to nearly 700 Wh/L for the Panasonic cells used by Tesla. Why does it matter? Energy density translates directly to range, and range, or rather lack of it, is right now the #1 challenge for electric vehicles. This is precisely why the Tesla pack weighs only twice more than the Leaf pack, yet delivers 3x more driving range. In other words, a Nissan Leaf using a hypothetical battery with cells at 700 Wh/L should be able to deliver a range of 120 - 140 miles, instead of the present 80 miles. I want one of those!

Second, the use of large pouches makes it necessary to have dual levels of packaging, one at the module level, then again at the pack level. This adds unnecessary weight and volume to the pack. Look at the energy density for the module and the pack. For the module, it is down to 131 Wh/L, and for the pack, it is a dismal 49 Wh/L. 

Another way to look at this mechanical inefficiency: The total weight of the 192 cells is 151 kg (332 lbs) -- that's the part that really stores energy -- to which the steel boxes, plates, wire harnesses and electronics add another 144 kg (316 lbs) for a total pack weight of 295 kg (648 lbs). In other words, that's 316 lbs of added weight that contributes zero to energy storage. Each pound of weight in the Leaf battery pack stores 37 Wh of energy. By comparison, each pound of weight in the Tesla S pack stores 64 Wh of energy!....this Leaf pack design does not scale well for longer driving ranges.

This, folks, says that a Leaf is a good Gen 1 vehicle, but that Nissan needs to figure out major improvements to its battery if it is to become widely adopted beyond select green and affluent communities like our San Francisco Bay Area.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

68. AND THE MAGIC NUMBER IS 3K                                                                  

That is 3,000 mAh....this is the battery capacity that consumers will see in most mid-tier to high-end mobile smartphones for the foreseeable future. Why? It's simple, this is the capacity that gives consumers an honest full day of operation. 

This begs a first question: what is an honest full day? no one really knows since usage varies considerably across the consumer base. But manufacturers are not able to tailor the battery to different consumer groups, therefore, an honest full day of operation ought to fulfill the demands of the largest cross section of consumers, including the spectrum from travelers to stay-home parents and teenagers who are glued to their favorite social network app. It would be fair to say that an honest full day ought to deliver at least 10 hours of talk time per day, preferably more, and at least 10 hours of screen usage time, including web browsing and app usage.

The two charts below examine talk time and web browsing time for a number of commonly available smartphones as measured by GSM Arena in their battery tests. For talk time, the relationship is immediately obvious. More battery capacity equals more talk time. Simple and easy.  Some smartphone makers are a little better than others, but overall, there is a simple relationship that says that about 3,000 mAh gives about 20 hours of 3G talk time. Now these are lab-based tests, so in real life, you would want to give yourself a little extra margin.  But I would say that 3,000 mAh is probably sufficient for most phone-talking needs, most likely lasting you several days if all you do is only using your smartphone to talk. 

Now, talking on the phone does not need the screen to be turned on, but everything else, from simple messaging to browsing and app usage does. The screen is a major power hog as I explained in a previous blog. This is where the battery begins to get challenged. The next chart shows measured usage time for web browsing, a good proxy for having the display as well as the radios turned on.

The picture now gets a little more involved. Clearly a bigger battery equals more time, but also the choice of smartphone does matter. For example, Apple and Sony seem to do a better job managing the power budget than HTC and LG do. Nonetheless, the chart is also specific in saying that if you are gunning for about 10 hours or more of screen time per day on a device that has a 5-in display, then the battery capacity needs to be right around 3,000 mAh (or more).

So there you have it....anything less than 3,000 mAh will leave consumers unhappy with their battery performance. Anything much more than 3,000 mAh will leave the manufacturer with a more expensive battery that will not likely earn this manufacturer any additional sales. So it seems that 3,000 mAh will be the right figure for a little while.

Now let's find the approximate charge times for such a battery. Such a battery has an equivalent energy of about 11.5 Wh. So a standard 5-Watt AC adapter will charge this battery at nearly 0.4C (=5/11.5) for which the charge time is an agonizing 3+ hours (see my earlier post on charge times). New AC adapters capable of charging at 12-18 Watts will accelerate the charge times. In other words,  such larger batteries will undoubtedly go hand-in-hand with fast charging...and that's what consumers will want to see in their mobile smartphones soon: a full-day battery that can be charge in the fastest possible time. Expect such new crops of smartphones to emerge in 2016.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com

67.  THE INNER SANCTUM OF A BATTERY & FAST CHARGING                               

Kevin Gibb of TechInsights published recently an article in EE Times that shows a teardown of the lithium-ion battery used inside the iPhone 6 Plus. While the teardown and the article seemed motivated by determining the cost of this battery -- somewhere near $4.00 -- it contained some very nice cross sectional photographs taken using optical and electron microscopy of the various layers that make the iPhone 6 Plus.  Anything that carries an Apple logo seems to attract a lot of attention, but the battery inside the iPhone 6 Plus is similar in performance and structure to many other Li+ (lithium-ion) polymer batteries used in mobile devices.  For example, the battery capacity of the iPhone 6 Plus is rated at 2.915 Ah, within a rounding error of the capacity of batteries used in the Sony Xperia Z3 and Z3+, the LG G3 and G4. Let's use this very nice teardown report of the iPhone 6 Plus battery to shed more light onto the inner structure of a lithium-ion battery and its workings especially in view of fast charging.

I described in an earlier post the various shapes of a lithium-ion battery. A 18650 cell is encased in a metallic cylinder, whereas a polymer one is a thin and flat pancake-like without any external metallic protection. Yet, the insides are nearly identical, all consisting of a set of electrodes called anodes opposing another set of electrodes called the cathodes with both sets of electrodes separated by a porous membrane called a -- hold your breath -- "separator." The first picture below shows a cross section of the polymer battery inside the iPhone 6 Plus viewed through an optical microscope. For reference purposes, the iPhone 6 Plus battery is approximately 3 mm thick. 

 

In mobile devices, the vast majority of batteries use a metal oxide called lithium-cobalt-oxide (LCO) deposited on an aluminum backplate to act as the cathode (the positive electrode during charging). You can see the bright white aluminum back layer in the photo above, but it is difficult to see the LCO layer at this magnification. The anode is nearly always made of a thin carbon graphite layer deposited on top of a copper backplate. There is a very thin separator layer that sits between each set of anode/cathode layers. During charging, the ions, yes, the lithium ions, travel from the cathode through the porous separator to the anode, and embed themselves inside the graphite. As every skilled engineer should know, charge balance means that there is an opposing current made of electrons that goes through the external circuit between the anode and the cathode. This means that maintaining a low electrical external path resistance is essential to the operation of the battery -- one of the reasons why aluminum and copper conductors are used.

The photo above shows a stack of alternating layers of anodes and cathodes. There are 11 anode/cathode layer pairs, which means the pitch is approximately 275 microns. This particular construction is unique to LG Chem with a stack of parallel layers. Other battery manufacturers use what is known as a jelly-roll, with the layers of anodes and cathodes rolled together like a cigar. This mechanical structure, while seemingly immaterial to the novice, plays a big role in the distribution of electrical current inside the battery, and consequently the governing degradation mechanisms. Let's zoom in a little more.

The second photograph shows a scanning electron micrograph (SEM) of two sets of anode/cathode layers. Now we can see the individual structural materials. The separator is typically near 10 to 20 microns in thickness. The graphite and LCO layers are often around 50 microns but can vary depending on battery capacity and current rating. This SEM now shows that the LCO layer is granular in nature. The graphite layer is granular too.  The grains, varying in size from a few to several microns in diameter, consist of crystalline layers -- a lattice-like -- where the lithium ions can embed themselves. In charging, they embed themselves in the graphite lattice, and in discharge, in the LCO lattice. The graphite lattice is pictured next using a transmission electron micrograph (TEM). The lattice is made of atomic layers that are a mere 0.34 nm apart -- think of it as atomic Swiss cheese.

The LCO and graphite have a limited capacity of how many lithium ions they can "hold" inside their lattice. This determines the amount of LCO and graphite material that is needed for a battery of a given capacity, i.e., of a given mAh. This in turn determines the energy density. Well, sort of, because there is another kink in the design of the battery, and that is the size of the grains (both LCO and graphite) and how tightly packed they are in the electrode layers. If the grains are too tightly packed, then the lithium ions will find it difficult to travel through all the grains; in other words, the maximum current capability of the battery is impaired. So you are hopefully getting a little taste of the various compromises a battery designer needs to go through....and we haven't even yet gotten to charging.

Now let's talk about the headaches that come with degradation of this structure especially with fast charging. High capacity and/or faster charging means a lot of ions need to zip in and out of the anode layers -- since the anode is primarily responsible for storing the ions during charging. Think of cars on a highway at peak rush hours....it's not easy; every pothole in the road now contributes to traffic flow. For example, small perturbances in the uniformity of grains means more ions will flow into one grain vs. another, thus creating differences in current density, and excessive stress on some grains (ultimately causing mechanical fracturing of the graphite lattice and loss of capacity). Small disturbances in the voltage distribution across the layers means some portions of the stack may see a potential difference between the anode and cathode that will promote the metallic plating of lithium -- a very detrimental failure mode especially present with faster charging. These are only but two examples of the degradation mechanisms. There are several more that are becoming prevalent in modern batteries with high energy density and faster charging. The task is to tame these degradation mechanisms to extract maximum performance, and that is now falling onto the next frontier of clever charging algorithms -- and that is what we do at Qnovo.

Fast charging a battery clearly involves a high degree of optimization in order to manage the large flow of ions. Historically, battery vendors did it while sacrificing grain size, or packing density of grain; in other words sacrificing energy density and overall battery capacity. This compromise is no longer acceptable.

© Qnovo, Inc. 2015 / @QNOVOcorp @nadimmaluf #QNOVOCorp    http://www.qnovo.com