CATL moves into sodium batteries

Business news | July 30, 2021

By Nick Flaherty

Chinese battery maker CATL has developed a sodium battery that will achieve energy densities of over 200Wh/kg without the fire risks of lithium. The company plans to develop hybrid battery packs of sodium and lithium ion cells with a custom battery management system that will operate well below zero degrees with safe fast charging.

“CATL has started its industrial deployment of sodium-ion battery and plan to form a basic industrial chain in 2023,” said Dr Qisen Huang, deputy dean of CATL research institute.

European companies such asFaradion and Tiamat have been commercialising soldium battery cells for several years.

“In terms of cathode materials there are currently the Prussian white cathode and the layered oxide cathode with industrialization potential. Their specific capacity reaches 160mAh/g, which is equivalent to the existing lithium-ion battery cathode materials. Based on previous research, we have redesigned the bulk structure of the material by rearranging the electrons and redesigned the material surface, which has solved the worldwide problem of rapid capacity fading upon material cycling, providing the opportunity for the material to be industrialized,” he said.

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The sodium cell needs a new architecture to achieve the same level of performance a graphite. “Regarding the anode materials, because sodium ions cannot move freely between graphite layers like lithium ions, CATL has developed a hard carbon material that enables the abundant storage and fast movement of sodium ions and features a unique porosity structure. The specific capacity of the material can reach more than 350mAh/g. It also has excellent cycle performance,” said Huang.

“In terms of the electrolyte, we have also developed a unique electrolyte system that is suitable for the cathode and anode materials. As for the manufacturing process, it is compatible with the current lithium-ion battery manufacturing process and equipment.

The energy density of the battery cells has reached 160Wh/kg, currently the highest level in the world, and the cells can charge to 80 percent in 15 minutes at room temperature.

Even in environments with temperatures below -20°C, the discharge retention rate is still above 90 percent, allowing the hybrid battery pack to operate in a wider range of environments.

“We integrate sodium-ion battery cells and lithium-ion battery cells into one battery system, mix and match the two kinds of batteries in a certain ratio and arrangement through series and/or parallel integration,” said Huang. “Thanks to the BMS precision algorithm, we are able to balance management different kinds of batteries. In this way, the battery is able to draw on the strong points to offset the weaknesses the current energy density shortage of sodium-ion battery is compensated, and also expand its advantages of high power and low temperature performance.”

“Overall, despite having slightly lower energy density than the current LFP battery, in low temperature performance and charging speed, our first-generation sodium-ion batteries have outstanding advantages, especially in extremely low temperatures and high power applications,” he said. “Thanks to its excellent thermal stability the battery well exceeds the national automotive battery safety requirements.”

CATL is inviting research institutions, upstream suppliers and downstream customers to work on the development of sodium-ion batteries.

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