Shenzhen Advanced Institute has made progress in flexible sodium-based dual-ion batteries

[ Instrument Network Instrument Research and Development ] Recently, Tang Yongbing (communication author) and his team members of the Research Institute of Functional Thin Film Materials of the Institute of Advanced Technology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, have made new progress in flexible sodium-based dual-ion batteries. Related research results "A Flexible Dual-Ion Battery Based on Sodium-Ion Quasi-Solid-State Electrolyte with Long Cycling Life" has been published online in the journal Material Advanced Advanced Materials, Adv. Funct. Mater. 2019 , 1906770).

Because sodium-based dual-ion batteries (SDIBs) combine the advantages of sodium ion and dual-ion batteries, they have high operating voltage, environmental protection, and low cost. However, it has been reported that SDIBs generally use a conventional liquid ester solvent as an electrolyte, so that the battery is easily decomposed at a high operating voltage. In addition, the solvent molecules of the conventional liquid electrolyte system and the graphite positive electrode are prone to co-intercalation problems, resulting in the peeling of the graphite positive electrode during the cycle. Therefore, the cycle performance of SDIBs based on liquid electrolytes remains to be further optimized.

In order to solve the above problems, Tang Yongbing team members Xie Donghao, Zhang Miao, Wu Yue and others developed a quasi-solid electrolyte (QSSE) with a three-dimensional crosslinked structure. At high voltages, the electrolyte has more stable cycle characteristics than conventional liquid electrolytes, and the three-dimensional polymer backbone also helps to alleviate the volume expansion stress of the electrode material. This QSSE-based SDIBs exhibit excellent cycle stability and a capacity retention rate of 97.5% after 600 cycles at 5C, which is the best performance reported in SDIBs. In addition, the battery has excellent flexibility and wide temperature domain performance (-20-70 degrees), and has good application prospects in the field of high performance flexible energy storage.

The research was funded by the National Natural Science Foundation of China, the Chinese Academy of Sciences, the Guangdong Province, and the Shenzhen Science and Technology Program.