High stability gel electrolytes for long life lithium ion solid state supercapacitor

¹ School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, People’s Republic of China
² Yangtze Delta Region Institute (Quzhou), University of Electronic Science and Technology of China, Quzhou, Zhejiang 324000, China

^* Corresponding author: drzhichen@163.com

Abstract

Lithium ion capacitors with liquid electrolyte are prone to leakage, combustion, explosion and other dangerous accidents. To solve these problems, the solid gel separator prepared by polyvinylidene fluoride - six fluoropropene (PVDF-HFP) is used in this work to improve the safety and stability of lithium ion supercapacitors. The PVDF-HFP based gel separator was used to replace the commercial separator and electrolyte in the lithium ion capacitor. The solid-state lithium ion supercapacitor was matched with porous carbon (PC) and hard carbon (HC). The maximum energy density of the device is 148.76 wh/kg, even at the power density of 33.6 kW/kg, which still retains 20.6 wh/kg. In addition, 83.3% capacity of solid-state lithium-ion supercapacitor is retained after 8000 times of charge and discharge. The requirements of high power energy density, high cycle stability and high safety are realized.