China’s CATL has become became the first EV battery maker to develop a sodium-ion battery, planning to set up a supply chain for the new technology in 2023. The battery reportedly has an energy density of 160 Wh/kg, short of the 200 Wh/kg density achieved by the LFP batteries that CATL have been supplying to Tesla. However, CATL has claimed that its second-generation sodium-ion batteries will reach the 200 Wh/kg in density.
According to CATL, the battery can be 80% charged in 15 minutes. In addition, at -20 degrees Celsius, the battery still retains 90% of its capacity. In combination with lithium-ion batteries, these new sodium-ion batteries will be used in EVs. The move is seen as a way to compensate for the latter’s relatively low energy density.
Sodium-ion batteries have recently been touted as one of the possible alternatives to lithium-ion batteries for reasons mainly related to costs and safety. Compared to Li-ion batteries, sodium-ion batteries have better thermal stability: they have a wider temperature range and experience no issues with thermal runaway. Also, it is non-flammable.
Most importantly, sodium is abundant. 2.8% of the planet is made up of the element. In comparison, cobalt, a common cathode material, represents merely 0.0029% of the earth. The share of lithium is only 0.0007%. Therefore, the extraction of lithium and cobalt have posed economic and environmental challenges. The adoption of sodium-ion batteries would mean a 10-20% reduction of cost compared to Li-ion batteries.
For China, the abundance of sodium is also particularly important for geopolitical reasons. 70% of the world’s lithium is concentrated in South America, while 80% of China’s lithium has to be imported.