High-performance solid polymer electrolyte facilitates the development of all-solid lithium batteries

A solid-state battery is using a solid electrode and a solid electrolyte. Compared with ordinary lithium-ion batteries, solid-state batteries have higher capacity density, smaller size, thinner and safer.It has become an important direction for battery research in recent years.

Recently, the Christopher Y. Li research group from Drexel University in the United States successfully synthesized a pure solid polymer electrolyte with interpenetrating cross-linking network, which is of great significance for the development of all-solid lithium batteries.

The electrolyte known as the "blood" of the battery is responsible for the transmission of ions and the formation of a stable intermediate role, which is an important guarantee for the function of the lithium battery. Solid electrolytes play an important role in the development and use of solid-state batteries.

Solid polymer electrolyte can give consideration to the conductivity of traditional liquid electrolytes and the processability and formability of solid resin compounds. It can improve the electrochemical performance of lithium ion, and at the same time, it can avoid the leakage, combustion, explosion and other dangerous accidents.

Based on cross-linked ethylene oxide, the researchers added a small amount of polypropylene carbonate and optimized its content to synthesize this interpenetrating cross-linked network pure solid polymer electrolyte. Related studies have shown that cross-linked polyethylene oxide (PEO) can effectively extend the cycle life of lithium metal anodes and improve interface performance.

This solid polymer can increase the lithium ion migration number three times while maintaining high ion conductivity and high chain flexibility. In the experiment of circulating symmetric lithium, the solid polymer electrolyte increased the circulating current density to 1.5 mA / cm2 and achieved an effective cycle time of more than 300 hours, which was the first time in a solid-state lithium battery. In addition, in the full-cell test using the polymer as the only separator and electrolyte and lithium iron phosphate as the cathode, the effective life of the battery (80% of the highest capacitance) exceeds 200 cycles, and has excellent cycle performance.

In general, this solid polymer electrolyte has good mechanical properties, ion conductivity and electrochemical performance, which can effectively improve the migration number of lithium ions and extend the safe cycle time at high current density. It also shows good compatibility with lithium iron phosphate cathode materials.

Reference:

Yongwei Zheng, Xiaowei Li, Christopher Y. Li. A novel de-coupling solid polymerelectrolyte via semi-interpenetrating network for lithium metal battery. Energy Storage Materials, 2020, DOI:10.1016/j.ensm.2020.04.002