Electric vehicles

09Oct 2019

I was beaming with delight when I read that John Goodenough, Stanley Wittingham and Akira Yoshino received the 2019 Nobel Prize in Chemistry for the “development of lithium-ion batteries.”

Wittingham’s initial work on batteries dates back to the 1970s while at Exxon. Goodenough’s seminal work on LCO cathodes at Oxford was published in 1980. Yoshino’s contributions on the graphite anode came in 1980s at Asahi Kasei in Japan. Sony converted their ideas into the first commercial lithium-ion battery product in 1991.

courtesy: The Royal Swedish Academy of Sciences

So it is about time that these scientists are recognized for their contributions and for initiating a revolution in energy storage. The award shines the light on the contributions of thousands of scientists and engineers who have diligently worked in the past decades to make lithium-ion batteries ubiquitous in our lives. Just imagine your modern digital life, your iPhone, or your Tesla vehicle, without a lithium-ion battery. You simply can’t!

With today’s Nobel award, lithium-ion batteries join the ranks of great inventions such as the transistor or polymerase chain reaction (PCR). The invention of the silicon transistor in 1951 became the catalyst that led to modern-day Silicon Valley. Kari Mullis’ discovery of PCR technique in 1983 set in motion a vast industry in biochemistry and drug discovery.

Nearly 30 years have passed since Sony manufactured the first lithium-ion battery. Over these three decades, the lithium-ion battery went from powering early models of consumer camcorders to transforming transportation. Nonetheless, the industry remains in its early days with many more challenges to overcome and discoveries to be made. 

As the adoption of electric vehicles accelerates in the coming years, the lithium-ion battery takes a fundamental role in our economy no less than that assumed by the combustion engine in the early part of the 20th century. Challenges in battery performance, safety, manufacturing, cost, integration with complex electronic systems, all must be resolved….challenges also mean opportunities for innovation, and opportunities for scientists and engineers to make lasting contributions.

In an era where the meaning of “tech,” especially here in the San Francisco Bay Area, has become synonymous with the creation of new gadgets or new business models, we should not lose sight that science remains the engine that powers technology.

24Jun 2019

You are an entrepreneur. You understand that batteries are powering the future. You think present battery technology falls short of market demands. You invented a new battery technology. You may even have some early prototypes that show some exceptional promise. So you start a new company to commercialize your new technology. Welcome to the Battery Gold Rush, ca. 21st century.

In the first Gold Rush, ca. 1849, many made fortunes, and many others lost riches. The new Battery Gold Rush will not be much different. So what factors should you be thinking about in your pursuit of the battery holy grail?

I will assume here that your battery technology is exceptional.You have tested it. It works in the laboratory. What I will address here is whether you and your investors will make money in this endeavor.

Five factors require consideration.

  • Are the economics of the battery market in your favor?

As a young graduate student several years back, I was constantly advised to move my thesis work away from silicon to gallium arsenide (GaAs). Known as III-V compounds for their position in the periodic table of elements, these new materials offered immensely better performance than silicon integrated circuits. Yet today, silicon dominates the semiconductor landscape simply because its economics far outweighed the economics of any other competing material system. There is a lesson here for emerging battery technologies to be economically viable from the get go.

As batteries increasingly become the energy source powering everything from smartphones to electric cars, one key economic metric to pay attention to is $/kWh: the cost per unit of energy stored within the battery. For the big manufacturers in Japan, Korea and China, the cost metric stands today somewhere between $100 and $150 per kWh.  It is forecasted to drop below $100 by 2025 at which point the cost of an electric car is equal to that of a traditional combustion engine vehicle. 

If your technology increases this cost, or your business model is based on a significant premium, then you are at risk of serious commercial headwinds. It does not mean that you will fail, but it means that the adoption of your products may be limited to niche markets, or that the rate of adoption may be too slow for your company to reach profitability.

  • Are you sure you have a working business model?

Most battery startup companies are exploring a wide variety of business models. Some favor building the entire battery. Others feel that manufacturing the materials are sufficient. A few others are content developing the technology and selling its underlying intellectual property. Which one is better? You will need to quickly validate the business model for yourself. 

If you choose to build the entire battery, will you be able to scale your manufacturing and distribution fast enough? Will you have the investment capital required to compete with the incumbents? Ramping up a battery manufacturing operation could cost in the billions of dollars. History has not been kind to battery startups. The rise and fall of A123 Systems is a business case worthy of serious study.

If, instead, you decide to build your business model on selling materials, your customers are now the battery manufacturers, the  vast majority of whom are based in Asia. Your technology may be differentiated but your customers are also your competitors. How will you protect your intellectual property? Will they pay you what you think is the value of your innovation? History also has not been kind here too. You will need to think out of the box to experiment and identify a working solution to the business model dilemma.

  • Will your product scale?

I have seen many amazing demonstrations in the laboratory of innovative battery materials. It is truly exciting to see this degree of innovation. But I am not aware that any of these recent battery material ideas have made it to volume production, at least not yet. As companies begin to ramp up manufacturing, many problems rear their ugly head. Uniformity of manufacturing across lots; meeting specifications on larger batteries; cost overruns; scarcity of available capital; investor fatigue are only a few examples of headwinds.

  • Do you understand your “exit” opportunities?

Your capital comes from investors who have an expectation of returns. A return of 5X or more is considered good; 10X or more is considered great.  So if you company requires $200 million to $500 million of capital to reach some degree of scaled operation (and hopefully profitability), then the expected “exit” valuation of your company is in the range of $1 billion to $5 billion. Congratulations if you achieved these valuations in your recent fundraising round. Very few companies can achieve this milestone. But will a potential buyer pay these valuations to acquire your company? Most incumbent battery companies in Asia have shown serious hesitation paying such valuations. You might, instead, choose to take the path of an initial public offering (IPO). A123 is such an example. But be careful, public markets have not been kind to company valuations with poor margins and tepid growth trajectories. In any case, the “exit” path — i.e., how you and your investor will turn your shares in the company into cash — is not well charted for battery companies. There are no easy precedents to follow and the path is fraught with incumbents who might choose to wait for you to reach desperation.

  • What about the Dragon?

China is rapidly becoming the battery manufacturing powerhouse. It means that Chinese battery manufacturers will likely be customers or partners of your company, or even potentially acquirers. Given the geopolitical tensions between the USA and China, it is difficult that the US Government will authorize the transfer of your technology or products to China under the export reform rules of the Defense Authorization Act of 2018. Will you choose to build your company anywhere else, may be in Europe or other geographies that will allow you to work with China? If so, you will need to figure that out early on in your endeavor.

My intent here is not to scare you off. The battery industry is in need of innovators. But innovation alone is not sufficient. Reaching financial success is essential to you, your employees and your investors. 

17Jan 2019

Ted Miller, senior manager of energy storage at Ford Motor Co., recently stated:  We don’t see another way to get there without solid-state technology.” The statement is in regard to more powerful batteries for electric vehicles. Mr. Miller goes on clarifying: “What I can’t predict right now is who is going to commercialize it.”

So what is a solid state battery and why is it so difficult to commercialize? 

First, let’s clarify some misconceptions. 

A polymer battery, known as a LiPo, is a lithium-ion battery. 

A cylindrical battery, like an 18650 cell (used in the early Tesla models) is also a lithium-ion battery.

A prismatic battery is too a lithium-ion battery with a hard shell.

And so is a solid-state battery. It involves newer manufacturing processes, but it is a lithium-ion battery. 

All of these variances of lithium-ion batteries have one physical principle in common: the lithium ions contribute to storing the electrical energy.

Simplistically, a lithium-ion battery operates with lithium ions shuffling back and forth between two electrical layers: an anode and a cathode. When the ions are at the cathode, the battery is discharged. When they move to the anode, then the battery is charged. The cathode and anode are called electrodes.

The motion of the ions between these two electrodes is facilitated by an intermediate medium called electrolyte. It is a solution that is electrically conductive: it permits ions to travel through it with little impediment. One key property is called conductivity: it is a scientific measure of the ease at which ions can travel through the electrolyte. High conductivity means the ions can travel easily and quickly. Low means the opposite.

In a lithium-ion battery, the two electrodes are immersed in an electrolyte solution. Today’s batteries use a liquid or gel-like electrolyte. Battery manufacturers go to great lengths to formulate unique electrolytes for their batteries. The formulations do have an impact on many of the battery’s specifications, in particular cycle life (the number of times a battery can be charged and discharged). 

In a solid-state battery, the liquid or gel electrolyte disappears. It is instead replaced by a “solid-state” layer sandwiched between the two electrodes. “Solid-state” means this layer is not a liquid, but a physical solid. The material can consist of a ceramic, glass, or even a plastic-like polymer, or some type of mixture of all three.

So why use a solid electrolyte? There are two major reasons. First, a battery with solid electrolyte occupies a lot less space than one with liquid electrolyte. That means one can pack more energy in the same volume. Consequently, energy density — an important metric of batteries — goes up.

The second reason is safety. Liquid or gel electrolytes are more prone to catching fire than a solid electrolyte.

Traditionally, the primary challenge with solid electrolytes is poor conductivity especially at room temperature (25 °C or 77 °F). A liquid or gel electrolyte has a conductivity that is about 1,000 times better than that of solid electrolyte. In other words, solid electrolytes exhibit a far higher resistance to the flow of lithium ions. This results in several performance challenges, starting with poorer cycle life and inability to charge at fast rates. 

Some companies proposed operating their solid-state batteries at elevated temperatures (> 80 °C) to improve conductivity. But this is not practical under most use scenarios.

Therefore the quest for solid electrolyte materials continues to be a much active field of exploration and discovery. There is confidence in the industry better materials will be discovered, yet, we really can’t predict when a breakthrough will be widely adopted. 

Another challenging aspect is the surface stability and manufacturability of solid electrolytes.  Unlike liquid solutions, glass and ceramic electrolytes are not deformable. They must be assembled with the two electrodes using high external pressure, equivalent to about 1,000 atmospheres. It becomes questionable whether existing battery manufacturing factories can be retooled for this purpose. If not, the economics of solid-state batteries will undoubtedly suffer as is the present case.

In a nutshell, there is much promise in breakthrough material innovations to make solid-state batteries a reality. Yet, many challenges remain ahead. I personally do not expect to see solid-state batteries in commercial scale for several years to come. We will continue to see evolutionary progress with traditional lithium-ion batteries especially as prices continue to decline.

But in all cases, solid-state batteries are subject to the same physical principles that govern traditional lithium-ion batteries. Consequently, many of the battery management solutions developed for traditional lithium-ion batteries will evolve and continue to apply. And that is good news.

17May 2018

I googled the question “ should I charge my phone to 100”. Google returned 467 million results. From folks offering opinions on “how to properly charge” to others calling on “science”, there seems no obvious consensus in the media. Yet,  unlike views on more socially charged topics, this question ought to be a lot simpler and ought to have a clear cut answer. Let’s explore.

I start with an easy experiment. Take two batteries. Charge one of them continuously to 100% and discharge it back to zero. Repeat. Take the second battery and charge it only to 90%. Discharge it. Repeat. Now compare the two batteries.  Are there differences? the answer is yes, there is difference. The battery that was charged to 100% will age considerably faster. 

What do I mean by aging? The technical term is “cycle life.” In practice, it means that the battery charged to 100% will lose its ability to store electric charge faster than the other battery. The difference between the two batteries can vary between 100 and 300 charge cycles.

So is that good? Well, it depends on what your use is. The definition of “good” is relative.

For a smartphone, my answer is “I really don’t care.” 

For an electric vehicle, my answer is “yes, it is better, but may be only marginally.”

For energy storage batteries used by electric utilities, my answer is “yes, absolutely.”

Now, let’s dive into the details.

A smartphone battery usually lives about 500 to 800 cycles. By cycles, I mean the number of times you will be able to charge it (to 100%) and discharge it before it becomes old and useless. Some smartphone manufacturers do better than others. Apple’s and Samsung’s batteries tend to be closer to 500 cycles. Others like LG, Sony and Huawei tend to be closer to 800 cycles. 

Let’s convert cycles to real-life years. Most smartphones are charged once a day. So 800 cycles is about 2 years of use before your battery becomes old. That corresponds well with the average time for consumers to upgrade. But wait, you might say you plan to keep your smartphone for longer than 2 years. What should you do?

Naturally, one option is to spend $30 to $50 once your battery is depleted and get your phone serviced after 2 years. The other option is to charge your phone to only 80% or 90% instead of 100%. That exercise will probably get you an extra year of usage.

But that is not the only way to get more longevity. You probably don’t know that if you use a small AC adapter instead of a bigger one, you will probably get the same benefit. For this method, look for an AC adapter that is rated 5 Watts, or use the USB port in your PC to charge you handset. And that applies to iPhones or Android phones. What do you give up? You are giving up fast charging. If you charge your handset overnight, then you really don’t care.

A self-serving plug for Qnovo: Smartphones with intelligent charging algorithms will take care of longevity issues for you so you really don’t have to think about this question and its answer. 

Now, let’s talk about electric vehicles. Should you top off the battery in your electric vehicle (EV)? First, it is important to know that EV manufacturers (from GM and Tesla to Nissan and VW) already limit the charging of the car battery to somewhere near 80%. The 100% that you read in your dashboard is actually 80% of the what the battery is rated for. That figure usually is sufficient to meet the warranty terms of the vehicle, often 100,000 miles or 10 years.

If you are leasing your car, then you really don’t care. Your lease will expire long before any meaningful battery aging sets in. But if you purchased your EV and plan to keep for a long time, then you may have an incentive to not top off your battery.

But wait, that is also not the only way to get more longevity. Every time you use a supercharger or DC fast-charging, you are causing serious damage to the battery. So instead, try to avoid using superchargers. This is particularly acute for the Panasonic batteries used in some of the Tesla models.

Lastly, I will add a few final words about electric utilities and batteries they use. These are complex systems that are slated to operate for at least 20 years! They are also very expensive assets that cost millions of dollars. So longevity is a serious matter. Naturally, users have no say in how these batteries get charged. Utilities and battery manufacturers do watch over these batteries so that they can last for a long time.

29Nov 2017

Congratulations, you just purchased a new Tesla model S electric vehicle (EV). You also committed an extra $2,000 to install a level-2 charger on a wall in your spacious garage. A level-2 charger will deliver 6 kW of power at 240 V to charge your big car battery overnight. Better yet, you are even considering investing an additional $20,000 to install solar panels on your roof and live a life with zero carbon. You might be cringing by now and thinking: “Wow, this is for the rich, not me.

So let’s consider instead a more socially responsible scenario. You leased a much more affordable Chevy Bolt that promises to give you 200+ miles of electric driving. You don’t have a garage. Perhaps you live in a large city so your car may be parked on the street. You are scratching your head: “How will I charge my car battery?” You might be lucky to charge your car during the day at work instead of overnight at home. But what about the weekends? No quick and easy answer.

As the adoption of electric vehicles becomes more widespread especially in congested urban geographies, questions about the charging infrastructure become prominent. Tesla leads in the deployment of their Supercharger network with over 1,000 charging stations installed worldwide, especially near major transportation corridors and highways. But the Tesla fast charging network is not compatible with other electric vehicles. Imagine that you can refuel your present vehicle at only one brand of gas stations, say at Shell only but not Exxon. No practical!

The buildup over the coming decade of a charging infrastructure that is publicly available to all electric vehicles is a must if EVs are to become a real alternative to vehicles powered by gasoline (or diesel). A fundamental requirement for charging is the availability of fast charging, more specifically, charging that can provide at least half-a-tank (or ¾ of a tank) in about 10 minutes.

Let’s do some simple math. An electric vehicle with a 200-mile range equates to a battery size of approximately 60 kWh. Half-a-tank is 30 kWh (or 100 miles). Charging 30 kWh in 10 minutes equals to 180 kW (or 3C effective rate). By the time we factor inefficiencies, the charging station needs to deliver a minimum of 200 kW. To put that in perspective, that is the amount of power used by an entire residential block! These chargers are big, expensive and hence have to be shared among dozens if not hundreds of vehicles.

But the infrastructure for fast charging is only half the problem. The elephant in the room remains: Can the battery itself charge at such a fast rate without being damaged?

The data suggest otherwise for the time being, unless we add a lot more intelligence to how we charge the battery.

The following chart shows the results of charging a battery at a slow rate compared to fast charging the same battery 30% of the time (or about once every three days) and 50% of the time (every other day).

The green curve shows how the battery retains its charge with slow charging. After 700 charge cycles (or about 130,000 miles of driving), it still retains 90% of its original charge. In other words, you can still drive 180 miles in what used to be a driving range of 200 miles. That is good!

The blue curve shows what happens if you charge 30% of the time. The capacity retention drops to 80% after 600 charge cycles. That is a rapid degradation. After 100,000 miles, your driving range is now 160 miles. It might be acceptable to some EV buyers but just barely. The resale value of your car has depreciated substantially below the average value.

The red curve spells major trouble. If you fast charge your electric vehicle every other day, your battery capacity drops to 75% of its original charge after only 300 cycles. That means that your driving range drops from 200 miles to 150 miles after about 50,000 miles of driving. What this graph does not show is that this battery is failing rapidly and has now become a serious safety hazard because of the presence of lithium metal plating. This is a serious problem!

So, if you own an electric vehicle such as a Tesla, and you are tempted to use the Supercharger network frequently, consider an alternative charging solution !!