Chinese researchers from the Dalian Institute of Chemical Physics have developed a 70kW-level high-power density flow battery stack. They claim it will be able to increase power density without adding costs.
The team was led by Prof. Li Xianfeng. They said compared with the current 30kW-level stack, the new one has a volume power density of 130kW/m3. The cost is reduced by 40%, they said.
The team noted the relatively high initial investment of vanadium flow batteries. The power density determines the cost of the stack: The higher the power density, the smaller the stack volume. That results in lower cost under the same power output conditions, they said.
Prof. lithium’s team said they developed a 70kW-level stack using a short flow path, an ultra-thin battery structure, low flow resistance and high distribution uniformity flow channels.
The researchers said they based it on self-developed highly selective weldable, porous composite membranes and weldable highly conductive bipolar plates.
The energy efficiency of this stack is 81.0% under 70kW-rated power charge and discharge conditions, and the energy efficiency is 82.1% under 60kW constant power charge and discharge. The stack maintains stable operations after more than 1,200 cycles, with only 1.7% energy efficiency degradation, they said.
Using this stack means a 20-foot container energy storage unit can be upgraded from 250kW to 500kW without greatly increasing the size of power units and the cost of system-supporting equipment.
Prof. Li said: “This 70kW-level stack can promote the commercialisation of vanadium flow batteries. We believe that the development of this stack will improve the integration of power units in energy.”
Photo: Xing Feng/Chinese Academy of Sciences
