Battery Technology Insights with Megan Wilson, Senior Research Analyst at Exawatt
Updated: Mar 11, 2021
Fayaz Ahmed: First of all, tell us a little bit about yourself and a little about your educational and professional background.
Megan Wilson: I grew up in rural Northern Ireland before moving over to England for University. My route into energy storage has been somewhat unconventional.
I read Natural Sciences at the University of Cambridge – an incredibly broad degree that encourages students to think and apply themselves across multiple scientific disciplines. It certainly shaped how I think about the world today, and how I apply myself to solving problems. Following my undergraduate I moved to the University of Sheffield to study Environmental Change with International Development. It was here I developed an interest in raw materials, supply chains, and clean energy.
I started my professional career just over 3 years ago as an analyst in solar photovoltaics, but it immediately became clear to me that energy storage was going to play an important role in transitioning to cleaner energy sources and so I persuaded Exawatt to allow me to pursue research in this space, starting with lithium-ion batteries.
Fayaz Ahmed: The Battery technology is poised to Power the World. How big of a role battery technology can play in the sustainable development and climate change mitigation efforts. Which applications of battery technology you are most excited about and why?
Megan Wilson: Batteries will play a significant role. Batteries will enable us to be efficient users of energy. They will also allow us to use clean energy sources, such as wind and solar, more effectively which means we can use more of them. A lot of clean electricity generated in this way is wasted today, as these systems cannot generate electricity on demand in the same way that conventional power stations can.
Batteries will also be important for providing affordable electricity to remote communities who do not live near a centralised grid.
I am most excited about batteries in electric mobility. If we can use batteries to electrify cars and other modes of urban transport, we can reduce inner city air pollution, a huge cause of premature deaths around the world. This is a positive change we can start to realise soon. But that is only the beginning. Developments in vehicle to grid (V2G) technology have huge potential to help us achieve our decarbonisation goals, as well as making electricity more affordable.
Fayaz Ahmed: Lithium-ion batteries are anticipated to have a high rate of deployment in the coming decades. Ideal applications of Lithium-ion batteries would be energy storage systems for renewables and transportation. Amongst Lithium-ion battery technology family which battery chemistry i.e. NCM and LFP has a better future and why?
Megan Wilson: If we focus this answer on transportation, NMC/NCA and LFP will both have an important role to play in the years ahead, and we will see a mixed market, with vehicles using both chemistries. Which chemistry will depend on the type of vehicle, and also on the needs and preferences of the vehicle user.
Compared to NMC, LFP cathode active material has much lower energy density, resulting in LFP battery packs that are bulky and heavy. LFP typically has poor performance in cold temperatures and requires a lot of battery management for optimal operation. In addition, it can be difficult to rapidly charge an LFP battery pack.
In the past decade, LFP batteries have primarily gone into buses and special-purpose vehicles. However, we are now seeing a renewed wave of interest in LFP for passenger cars due to its superior cost structure and the inherent safety that comes with the chemistry’s thermal stability. I should also note that today’s LFP battery packs are the closest thing we have to a “million-mile battery” as they can just cycle and cycle almost endlessly. A typical LFP cell can reliably cycle 2500 times in its first lifetime whereas a NMC cell will only give you up to 1500 cycles. From a cost perspective, LFP packs are about 20% cheaper than NMC packs, which is significant, but not game changing. However, when you combine cost and cycle life, the lifetime cost of an LFP battery pack blows NMC out of the park.
To summarise these pros and cons, if I want to drive a fast e-sports car, or travel 300+ miles and recharge in less than 15 minutes, then an LFP pack is probably not for me. If I want reliability, and a cheaper upfront EV cost, and don’t mind planning my journeys to incorporate longer charge times, then do I really need an NMC pack?
In energy storage systems (ESS) it is not worthwhile using NMC unless you are, for example, installing a backup power wall in your house and you are limited for space (and do not mind paying a premium). ESS should really focus on making use of second-life batteries, but also on low-energy-density chemistries such as sodium-ion, which have much lower costs.
Fayaz Ahmed: To further improve the Lithium-ion batteries. There is a general trend of moving from graphite based anode towards a Li metal or silicon anode. On cathode side, committing to cobalt-free cathodes and moving towards a high nickel cathode design? What engineering and operational challenges battery industry need to overcome before mass manufacturing of these new electrode materials?
Megan Wilson: I am in the relatively early days of my investigations into active material, but what I have found interesting is the variety of different methods being used by the industry to overcome the same technical challenges.
For example, with silicon-doped anodes, efforts to limit material expansion and improve cycle life have materials scientists deploying different techniques, from growing unique silicon nanostructures, to creating clever polymer coatings, or even pre-lithiating the material. What I see at the commercial scale is a combination of techniques to create the perfect recipe.
Wet-electrolyte lithium chemistries are somewhat limited by what they can do with the anode. Solid-state electrolytes will really enable the shift to pure silicon or to lithium-metal anodes.
Compared to the cathode, the energy density of the anode is easy to improve. With the cathode active material being the biggest single cost of a battery, improving the anode only puts more pressure on the cathode. It is an area that warrants so much more research.
Making your cathode cobalt-free is not necessarily going to improve your battery either. In NMC/NCA cathodes, cobalt is very important in stabilising the layered metal oxide structure when lithium ions are shuttling between electrodes. Efforts to squeeze almost all the cobalt out of materials have led to inevitable compromises in capacity and performance. I don’t think cobalt is going anywhere soon, but high-nickel cathodes such as NMC811 use significantly lower quantities than NMC111, meaning that cobalt is no longer the driver of cost that it used to be.
Fayaz Ahmed: Tesla introduced new battery cell design on their battery day. Tesla says its new cell design should give its vehicles a 16% increase in range thanks to a 5x increase in energy. Cylindrical cells have been there for many decades but they seem to have come up with the radically different idea of building these cylindrical cells, right? Please tell us a bit about new cell design and what’s so innovative and exciting about it.
Megan Wilson: It is cool to see Tesla really pushing the limitations of cylindrical cell design; first its move from 18650 to 21700, and now to 46800 without tabs. An obvious benefit of moving to larger cells is that the volume-to-surface-area ratio increases. In other words, more of the cell’s volume is taken up by the contents, not the casing. This means higher energy density. It’s these kinds of tricks, and other less-obvious, more-ingenious methods, that Tesla is employing to eke out incremental performance gains and lower the cost ($/kWh) of batteries, when innovation at the chemistry level becomes trickier, or you can’t squeeze raw material and production costs much more.
We also observe this kind of design innovation at the cell level in other manufacturers. For example, BYD’s blade battery is just an optimised pouch cell that can squeeze more out of LFP than in a more traditional format.
Fayaz Ahmed: Battery prices, which were above $1,100 per kilowatt-hour in 2010, have fallen 87% in real terms to $156/kWh in 2019, according to the latest forecast from research company BloombergNEF (BNEF). BNEF’s 2019 Battery Price Survey has predicted that as cumulative demand passes 2TWh in 2024, prices will fall below $100/kWh. What is Battery prices reality? And how confident you feel about the path to achieving $100/kWh by 2024?
Megan Wilson: There is a lot of focus on price in this industry. At Exawatt we are firm advocates of using cost as a reliable measure of an industry’s progression. Price is largely a function of supply and demand and it doesn’t tell you a lot about the cost fundamentals. The steep drops in price that we have seen in the last decade are a result of rapid scaling of production capacity for all material components that go into a cell.
In China I saw the cost of lithium-ion battery packs fall below $100/kWh back in 2019. Now it is closer to $80/kWh. There are obvious raw material cost differences between NMC and LFP packs, but even NMC packs can be made for close to $100/kWh today. The cost of making a battery pack will continue to fall in the short term, but much more slowly as we get closer to the fundamental limits of material costs. At this point, the critical driver of lower $/kWh will be battery performance.
Getting back to your question on price, we are highly confident that the price of battery packs will fall below $100/kWh before 2024, based on our fundamental cost and performance analysis, and assuming a reasonable gross margin.
Fayaz Ahmed: Particularly, there is a lot of hype about solid-state batteries. Can solid-state batteries live up to the hype? If solid-state batteries succeed, do you see them competing or complementing Li-ion battery technologies? And what particular chemistries within Solid State Batteries are promising candidates?
Megan Wilson: Shifts in technology tend to occur when we get improvements in performance for the same or lower cost in $/kWh. If solid state batteries (SSB) are to compete with current lithium battery technologies, their $/kWh cost must be broadly competitive with that of the incumbent competition. I know this is possible from my own cost analysis.
However, in addition to being more energy dense than today’s wet-lithium-ion battery cells, SSB cells are likely to be inherently safer (no flammable liquid electrolyte). This means that packaging may not need to be as bulky enabling the technology to press home their energy density advantage even further at the pack level. The consequent savings in weight and size will translate into added vehicle range, which may allow solid-state packs to carry a premium price.
People talk about solid state being a technological paradigm shift. I disagree with this. Solid-state batteries are still lithium-ion batteries at the end of the day (they still exchange li-ions). In fact, they share a lot of materials in common with today’s wet-electrolyte lithium-ion batteries. What we will eventually see is a gradual succession to solid state because they can push the theoretical limits of today’s batteries (for the same cost) and bring additional benefits.
With regards to solid-state chemistries, just like with conventional lithium-ion batteries where we have a variety of ‘flavours’ denoted by their cathode chemistry (NMC, LFP, LMO etc.), we see a similar level of diversity in solid state, mostly distinguished by their solid electrolyte chemistry (ceramic oxide, glass, sulphide etc.). Each has its pros and cons, and just like in conventional lithium-ion batteries, where LFP suits certain applications better than NMC, we might not necessarily see one solid-state chemistry rise above all others.
Fayaz Ahmed: It is commonly agreed that a noticeable market uptake of the All Solid State Batteries with Li-metal anodes cannot be expected before 2030, especially in electrification of transport and stationary energy. What do you think about this timeline?
Megan Wilson: We can expect to see some solid-state batteries (SSB) with li-metal anodes (and other anode materials) in the market before 2025, and I would not be surprised to see large-scale production of SSB before 2030. What I will stress though, is that solid-state batteries’ full performance potential will probably not be achieved until later.
It is also very unlikely we will see SSBs in stationary energy storage in the next decade, unless in second-life use. Their strengths play to mobile applications, where energy density matters more.
Fayaz Ahmed: West is playing catch-up with Asia, predominantly Japan, South Korea and China in the race to secure battery value chain -- from extraction of raw materials all the way through to recycling at the other end of the value chain -- in order to maintain a competitive edge in the sector. Who do you think will be the battery powerhouse of the future and why?
China, Japan and Korea together account for approximately 90% of global lithium-ion battery production today. Asia's position as the current battery powerhouse is largely due to its "first-mover advantage", an economic term used to describe a product or entity that has gained a competitive advantage over others by being the first to market. Asia has been in the lithium-ion battery game for about two decades, and in this time it has built its own supply chains, developed expertise, and achieved a paramount economy of scale. Although it’s not widely reported, Asia has also already been quietly building battery materials recycling capabilities and recycled materials are already feeding back into the supply chain. It is going to be difficult for those outside to compete.
Increased demand for lithium-ion batteries in Europe and the US has opened up opportunities for new battery players in the west, and we see fully European companies such as Northvolt forging ahead with ambitious plans, and others following in its footsteps. However, Asia will continue to have significant influence in the west. These European companies still require Asian expertise and skills to scale production, and they will still need to tap into existing Asian supply chains to source enough raw materials. The west is unlikely to be able to succeed on its own.
Senior Research Analyst at Exawatt