E-Mobility Engineering 017 l ECE Doosan electric excavators dossier l In Conversation: Matt Faulks l Battery testing focus l Battery Show North America 2022 report l Ariel Hipercar digest l Cathode materials insight l Thermal management focus

One-pot process Addressing this issue, Nano One Materials has developed a ‘one-pot’ process to reduce the complexity of the manufacturing process. “When you look at cathodes for lithium batteries, there are the lithiated NMCs with transition metal oxides, and the other class is the phosphate LFPs, sometimes with manganese which gives you LMFP,” says Dr Stephen Campbell, CTO at Nano One. “They are very different materials with different markets, and there is no single winner as they are application-specific. Instead, we have a technology that changes the way the materials are made.” “NMC is made using metal sulphates as a precursor, but the conventional way of manufacturing makes it difficult to meet the sustainability requirements of Europe and the US, as there is a lot of sodium sulphate as waste,” he says. “That means you can’t take the manufacturing from China and put it into the US or Europe.” Rather than using sulphates as a feedstock, Nano One uses metals with a bio-material that burns away as ash. “The big difference is the ‘one- pot’ approach,” Dr Campbell says. “The traditional process has up to 12 manufacturing steps – with a precursor, grinding with lithium hydroxide as a strong alkali, drying it and keeping it dry, then putting it in a furnace to get the lithium soak into the oxide – which can take 30 to 40 hours. That was fine with cell phone batteries but producing 1 Mt of lithium produces 2-4 Mt of waste.” “Instead we put lithium, nickel, manganese, cobalt and all the doping materials into a reactor. The chemical process is very different from the conventional process, and the reagents are bio-derived to reduce greenhouse gas emissions,” he says. The process doesn’t have a coating step; the cathode materials come out coated. The reagents also burn up, reducing the waste. “We have a shorter firing time in oxygen, less than 10 hours, which leads to a more durable material,” Dr Campbell says. “We make our own pouch cells and have seen some very promising results.” The company is applying its process philosophy to a range of cathode active materials. The plan is to build up manufacturing capacity for LFP in North America alongside what it calls a Multi- Cam Piloting Hub, which will develop piloted processes for high-nickel NMC and manganese-rich materials. It is buying the only existing LFP plant in North America, in Canada, and plans to pilot the process for other materials. “We are also working with collaborators on next-generation materials. It’s a different chemistry with the phosphates, so there are different reagents and feedstocks, but the materials are all available outside China as we are looking to establish a sustainable supply chain,” Dr Campbell says. Microwave processing Process developer 6K is using microwaves to create high temperatures that create cathode materials with smaller grains as well as single crystals. Its UniMelt process can be used to create NMC811 crystals of 1-3 microns as well as single-crystal NMC cathodes. The ability to produce smaller sizes by adjusting the manufacturing process enables cathode developers to improve charge time, extend runtime and improve power. “We are responding to demand from customers in the EV and consumer battery markets who are seeking higher nickel content and smaller NMCs,” says Dr Richard Holman, VP of battery products at 6K. “Our team was able to adapt the NMC622 process to produce NMC811 at more than 200 mAh/g, and dial in sizes from 1 to 3 microns. The microwave process can be used with essentially any chemistry, says the company. The combination of chemistry and morphology control means materials can be independently designed to optimise them for power, energy density and cost. 6K has already used the process for LTO, NMC333, 532, 622, 811 and higher-nickel NMC cathodes as well as silicon anodes including nano- structured foam and intermetallic composite powders. Conclusion There are many options for cathode materials in lithium-ion batteries for e-mobility applications, from NMC to LFP and spinel for solid-state cells. Research into the different materials and crystal structures continues to boost the energy density of cells, while new manufacturing processes are aiming to deliver these materials more cost-effectively for the sustainable high-volume production needed to supply the industry around the world. Producing single-crystal cathodes using a temperature microwave process running at up to 6000 K (Courtesy of 6K) January/February 2023 | E-Mobility Engineering 63 Deep insight | Cathode materials