Institute of Electrical Engineering,Chinese Academy of Sciences
Research Progress

Stockings Battery Birth

Lithium-ion flow battery using "stockings" as the key component, has been developed successfully in the Institute of Electrical Engineering, Chinese Academy of Sciences (IEE, CAS). The “stockings battery” shows a good charge -discharge performance.


Lithium-ion flow battery is a new kind of energy storage technology. The concept of lithium-ion flow battery was proposed independently and got started in 2010 by Dr. Chen Yong-Chong, director of the Energy Storage Technology Research Group of IEE, CAS. "In fact, the Massachusetts Institute of Technology has made a similar concept and carried out research, but did not disclose in that time. American scientists want to use it to develop the power battery of electric vehicles, while we mainly develop it for the distributed grid energy storage equipment. The research focuses are not the same". Dr. Chen said, "The combination of lithium-ion battery and flow battery brings a good prospect for lithium-ion flow battery in the application as the energy storage technology for the new energy grid. Now the technology principles verification has been completed and it’s going into the critical periodic for basic technologies development".   


One of the key technologies is how to reduce the battery cost by increasing the battery power density. In cooperation with Beijing HAWAGA Power Storage Technology Co. Ltd., Dr Chen’s team developed an innovative design to reduce the battery internal resistance and thus increase the battery power density. For this technology, a "porous collector" is needed for storing and releasing the electronic energy. "Theoretically, the porous current collector should be electronically conductive and to be thin as possible, also it should have enough porosity to allow lithium ions to pass rapidly", Dr. Chen said.


The research group has experimented many different kinds of porous materials, and finally fixed on stockings material. "The main component of stockings is polyamide (commonly known as nylon). Stockings material has an elastic porous structure and high strength, it is also resistant to electrolyte". After coating with electrical conductive slurry, stockings became the perfect material for porous collector.


Using stockings material as the porous collector, the power density of lithium-ion flow battery increased by more than an order of magnitude. More importantly, the stockings material is very cheap, so the battery cost can be significantly reduced. "If the new technology achieve scale energy storage applications, the cost is the key. Currently, we are continuing to optimize this new battery. It’s expected to be two or three years time, this 'stockings' battery will gradually enter the practical stage". said Dr. Chen, “Approximately 5 years after, this new energy storage technology can be estimated in the large-scale application of new energy. Low-cost energy storage battery technology will be entering a new era of development”.