It seems that all the hype recently has been focused on solid state batteries and, while we do expect it to eventually become the default technology, the prevailing opinion is that it will become widespread in automotive applications no earlier than the end of the decade.
The lithium-ion battery cost curve is, as expected, reaching a point of diminishing returns. Further technical breakthroughs are needed in the meantime, however incremental, to keep the momentum going. There are silicon anodes, tabless cell designs, structural efficiencies, such as Cell-to-Pack, universal cell formats, and many other advances being made, but a new manganese-rich cathode chemistry offers a means of doing away with cobalt, by far the most expensive battery material, while avoiding the hit to energy density that is associated with LFP. It also has the potential to democratise and diversify the raw material supply chain to a point where extraction is more sustainable, both environmentally and ethically.
This is commonly named LNMO (Lithium-nickel-manganese-oxide), or ‘high voltage spinel cathode’, and is seldom talked about, despite being planned for series production in at least two applications at the end of this year.
Down with cobalt
Some OEMs are intending to remove cobalt ‘as soon as possible’, not just because of ethical concerns surrounding the mining of the material, but because of the volatile prices. And even the prospect of sourcing cobalt as a by-product of copper and nickel refinement does little to alleviate the concerns around its cost.
Manufacturers have been continuously reducing the cobalt content in NMC and NCA batteries, while at the same time increasing nickel for energy density to the point where the state of the art is CATL’s NMC 811 (80% nickel, 10% manganese, 10% cobalt), and there are even plans for NMC 9.5.5 from SK Innovation. Unsurprisingly, this practice of thrifting cobalt has had its side effects on thermal stability, resulting in some high-profile battery fires. Regardless, supply of higher metallurgical grade lithium hydroxide needed for these high-range chemistries has experienced a shortage, which is slowing down the transition to NMC 811.
That is not to say that LFP, the current cobalt-free option, is stagnating. Advances like Cell-to-Pack, notably championed by BYD, are offsetting the energy density disadvantage to an extent, and there are cells, such as that from Guoxuan High Tech, that are exceeding 210 Wh/kg. LFP is rebounding in China and is now almost as widespread as NMC. European manufacturers like VW Group, Renault and Daimler have plans to offer LFP as a low-cost entry-level option.
Manganese: a third way
Ideally there would be a cathode option that does not employ cobalt but offers an acceptable energy density – higher than LFP but close enough to NMC to replace it in most applications.
At the time of writing, there are a handful of OEMs and suppliers planning high-voltage, nickel-based, cobalt-free batteries for rollout in the next couple of years, without explicitly referring to LNMO:
- VW Group, likely through Nano One: ‘high manganese and cobalt-free’ cells from 2023, while LFP cater for entry and NMC for high performance variants, respectively.
- Tesla: ‘nickel and manganese with zero cobalt’ option for mainstream/volume variants, while LFP and ‘high-nickel’ cater for entry and commercial models, respectively.
- SVOLT: cobalt-free ‘NMx’, first application reportedly to be in a Great Wall vehicle, and potentially supplying Stellantis in future.
Other assumptions can be made, albeit with weaker evidence, that LG Chem and Panasonic are researching this chemistry.
Being manganese-rich has its advantages. Manganese deposits are more diversified in their location globally, which is good for prices (18 times cheaper than cobalt at the time of writing), but also prevents the likelihood of one country or company holding too much influence over the supply chain, for instance with China and the DRC. Manganese ore is also more concentrated than nickel and cobalt, so the extraction process is potentially less environmentally damaging.
There is always a catch
The glaring question is: if you subtract cobalt but maintain nickel, however small the amount, what do you do about thermal stability? Like any other new battery technology, there is a catch, and the consensus seems to point towards cycle life and thermal stability as the technical hurdles to overcome. Unsurprisingly, Tesla recently stated that pilot production of its new 4680 cell (assumed to utilise this new chemistry at the plant in Germany) will be delayed by 12-18 months.
The chart below illustrates our view of how BEV cathode chemistry will develop over the production forecast horizon, capturing the trend towards high nickel, high manganese and low/no cobalt. Of course, the supply chain and battery production localisation have a huge influence on technology selection. As enticing as LNMO is, it will, in reality, take some years for the supply chain to transition to this – if it does. Although manganese deposits are abundant and more are being discovered, production is currently nowhere near the level of the other key metals. On the other hand, many OEM-supplier relationships are still being established, and that, coupled with the impetus for continuous improvement and the relative ease with which batteries can be upgraded, make this a fluid situation.
Therefore, there is still more upside potential to low-cobalt chemistries, and even further when solid state electrolytes open the door to a whole new landscape of anode and cathode materials. One can only hope that the automotive battery sector can, at that point, become truly sustainable without the need for a vast and damaging mining industry.
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LNMO = Lithium Nickel Manganese Oxide
LFP = Lithium Iron Phosphate
NMC = Lithium Nickel Manganese Cobalt Oxide
NCA = Lithium Cobalt Aluminium Oxide
NMCA = Lithium Nickel Manganese Cobalt Aluminium Oxide