🔋Why So Salty

The future of Na-ion batteries in replacing the powerhouse that is Li-ion batteries.

Jun 15, 2022

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Beyond Li-ion

I have previously talked about solid-state batteries, flow batteries, and metal-air batteries which all are emerging battery technologies attempting to solve problems with Li-ion batteries (LIB) as they stand. None of these have been fully commercialized and there may be years of development on many projects anyway, but it is helpful to understand our potential energy future. Solid-state batteries are attempting to solve the ‘holy grail’ of batteries in a way, using a solid electrolyte which theoretically increases energy density, safety, and charging rate. Flow and metal-air batteries if successful are more feasible for long duration applications for homes, businesses, or the grid. They have the ability to use cheap/abundant materials cutting out much of the supply chain hurdles that Li-ion batteries are facing (lithium, nickel, cobalt, manganese) as well as non-linear cost scaling.

In a world where electric vehicles soak up demand for Li-ion batteries, that leaves any other applications on the backburner or driving up prices for a limited number of resources (Gigafactory production outpacing battery material mining). This would abate slightly in a world of solid-state batteries, but they will often be using the same cathodes as Li-ion batteries, while some will use more lithium at the anode (currently graphite).

Currently the United States and many others are attempting to destroy the fossil fuel industry in which the world is still reliant. Further, nuclear power and natural gas are practical and very energy dense sources of energy which make very material progress in reducing emissions, however these are not currently in favor. This means there will be many more solar and wind projects going forward. Especially considering the recent supply chain issues and what I believe is going to be a new era of de-globalization moving forward, the replacement of LIBs with cost-reducing emerging technologies will be make-or-break for many renewables projects in terms of cost.

This week I am introducing sodium-ion batteries (SIB) as an alternative for LIBs. They work in the exact same way as LIBs, so check out my Ultimate Battery Guide if you want to learn more about what they are made of and how they work.

Pros

SIBs simply use sodium instead of lithium for the ion of choice to make the voyage to and from the cathode over and over again. Sodium chloride is your normal table salt and what makes the oceans salty, but sodium metal alone comes in a shiny solid metal form (fun fact: it looks like steel or any metal, but it is extremely soft and can be cut through easily with a knife… it also explodes in water…). It is orders of magnitude more abundant than lithium which gives it a cost advantage. SIBs can use the same battery production infrastructure as LIBs so it could be substituted in production with minimal effort. They are also capable of becoming solid-state batteries down the road as well. Other than some other potential advantages like different material subsets for cathodes and electrolytes they provide, cost is pretty much the main factor and that’s our biggest consideration anyway.

Cons

Sodium and Lithium are group 1 elements (alkali metals) which carry a +1 charge as an ion. Since intercalation (insertion/extraction of Na/Li ions from the host structure) is the mechanism by which batteries work, small ions are preferable. It is like trying to sneak through a crowded group of people without disturbing anyone. A little kid is going to be much better than Shaq, who would end up pushing around half the people in the room, lol. Same idea goes for batteries, you don’t want the intercalating ion disturbing its surroundings or getting stuck. Sodium has a larger ionic radius than lithium meaning it is slightly less favorable for intercalation.

Sodium is heavier (22.99 vs 6.94amu) and has a slightly different potential which both mean that a sodium-ion cell has less theoretical energy density. This is an extremely important factor and basically determines how much juice the battery has in the same amount of size.

SIBs cannot use the traditional graphite anodes that LIBs do which is another disadvantage. Alternatives have been used and studied but overall, the SIB world is not as far along as the LIB world. The lack of maturity in the area compared to Li-ion is another con in itself.

Conclusion

Lithium and other battery metal prices soaring increases the need to find low-cost energy storage. SIBs are one of these technologies that explores other elements to entirely avoid the lithium industry. SIBs would still have issues with nickel, cobalt, or manganese; however, lithium is one of the bigger issues.

In the future we could have more lithium mining capability as it takes a while for new mines to come online as they try to increase production to meet demand. The beyond Li-ion technologies including SIBs will also have time to mature and develop over the same time period. The two extrema options I see as possibilities for long term 8+ years out.

First is the demand for LIBs and therefore lithium metal subsides as grid scale renewables is deemed unviable economically, the mining requirements to make the green transition are not accepted worldwide, and many people choose either hybrids or internal combustion vehicles instead of EVs. Lithium ion or solid-state would take all of the market share of batteries in this scenario (I’ll name the battery bear case). The second is a more divided and application specific industry. Battery demand in all sectors across vehicles and grid backup storage remains high enough for all technologies to continue competing it out, but prices remain low enough that it is still considered viable through increases in lithium mining production for example. High performance Li-ion or solid-state batteries would likely take precedence in electric vehicles or other energy intensive use cases while cheaper alternatives take the market of grid projects, homes, and less energy demanding applications (I’ll call this the battery bull case).

Even in a realistic scenario where we are somewhere in between, it is not far-fetched to think that Na-ion batteries could be used a cheaper car with that doesn’t have quite the same range to lower prices. This is likely a great option, as manufacturing for SIB and LIB is quite similar anyway. There could be a cheaper model of the same car with cheaper battery packs. We already see a Chinese battery manufacturer making commercial Na-ion cells. SIBs don’t offer the same cost scaling potential as flow or metal-air for the grid, but certainly have the potential for lower costs compared to Li-ion that is used currently. It is possible we see them there as well. Until next time,

-Grayson