Zinc-iodine single-flow battery concept dramatically increases battery energy density

Recently, the research team led by Researcher Li Xianfeng and Researcher Zhang Huamin of the Energy Storage Technology Research Department of Dalian Institute of Chemical Innovations innovatively proposed the concept of a single-flow zinc-iodide battery to achieve the utilization rate of electrolyte in the single-flow zinc-iodine flow to nearly 100%. In turn, the energy density of the battery is greatly increased. The research results were published online in "Energy Environ. Sci."

Large-scale energy storage technology is a key technology for realizing large-scale utilization of renewable energy. Flow batteries have the characteristics of high safety, long cycle life and high efficiency. It is one of the preferred technologies for large-scale energy storage. Zinc iodine flow battery is a kind of flow battery technology. Because of its high energy density and environmental friendliness, it has received more and more attention in recent years.

In the previous research, the research team improved the cycle life and power density of the zinc-iodine flow battery by optimizing the electrolyte composition and membrane materials. However, the problem of relatively low electrolyte utilization caused by the internal blocking of the zinc-iodine flow battery remains to be solved.

The team proposed the concept of zinc-iodine single-flow battery. Unlike traditional zinc-iodine flow batteries, zinc-iodine single-flow batteries have a flow circulation system on only the negative electrode side, and the positive electrode electrolyte solution is directly fixed in the positive electrode cavity. Since the positive electrode of the zinc-iodine single-flow battery is solid, there is no flow circulation system, so there is no problem of blocking the solution line and the pump. Therefore, the iodine ions can be charged to the solid iodine element, so that the utilization rate of the electrolyte is close to 100%, which greatly improves The energy density of the battery. In addition, researchers have also increased the power density of zinc-iodine single-flow batteries by using porous carbon felt as electrodes. The experimental results show that the zinc-iodine single-flow battery can be operated stably for more than 500 cycles at a current density of 80 mA / cm2, without significant performance degradation. (Xie Congxin)