Annexure – 6

annexure 6 FUTURE BATTERIES

We briefly discuss here some of the recent developments which may impact EVs in the middle to long-term future. 1. Enhancing energy density of NMC/NCA - Graphite battery: The developments have been going on in two directions: Reducing Cobalt and enhancing Nickle in Cathode: Early NMC cells were NMC111, implying Nickel, Manganese and Cobalt were in equal proportion (1:1:1). Over the last five years, one saw NMC433, where the ratio of Nickel was enhanced; One saw reduction of Cobalt content as opposed to Nickel and this reduced cell costs and increased energy density. Then came NMC532, where Cobalt content further went down, and costs decreased whereas energy-density increased. Then emerged NMC622, where the Nickel ratio was further enhanced. The latest cells are NMC811, where the Nickel ratio was enhanced to 80%, further reducing costs and enhancing energy density. Some recent work has given Nickel-rich Cathode, where Nickel is up to 95% and Cobalt reduced to 4%. This has pushed up the energy-density to 300 Wh/kg. However, the cells cannot be fast charged at high temperatures. At 45°C, charging is to be limited to 0.2C (full charge in about five hours). An alternative was to use Silicon along with Graphite in the Anode. One can get energy density of 280 Wh/kg, but the problem is that Silicon can expand 400% in volume during charging. As a result, one must charge very slowly (limiting to 0.5C). Discharge rate is however not a problem. Also, the life cycles considerably go down. In effect, while enhancing energy-density decreases costs, it has an impact on the safety and charging rate. 2. An alternative is to use LTO. The nergy-density is unlikely to cross 100 Wh/kg, implying this will be significantly higher weight and size as well as higher costs as compared to NMC. However, as mentioned earlier, it is remarkable as far as safety and charge-rate is concerned.

3. A few years ago, the Metal-Air battery was touted to be a better alternative as compared to Lithium batteries. But the promise has largely faded away. One may see Lithium–Metal anode in the future. But to become competitive with today’s NMC battery may take several years.