Enhancement of rapid charging capability of organic radical battery using ethylene carbonate-based electrolyte containing LiFSI

Abstract

In poly(2,2,6,6-tetramethylpiperidinyl-N-oxyl-4-yl methacrylate) (PTMA) gel with lithium bis(fluorosulfonyl)imide (LiFSI), the salt concentration dependence on the ionic conductivity and the viscosity indicates that LiFSI has a high degree of dissociation and weak interaction with the PTMA. These properties retain fast charge transportation even at a high salt concentration in the gel. When salt concentration is increased to 1.5 mol/L, the diffusion coefficient for the gel containing LiFSI is almost unchanged. The capacity at 120C charging in organic radical battery (ORB) is increased by 20 mAh/g as LiFSI concentration increases from 1.0 to 1.5 mol/L. These results suggest that the increase in LiFSI concentration suppresses the shortage of electrolyte anions, which is involved in the oxidation reaction of nitroxyl radicals, at high rate charging. The ORB with 1.5 mol/L LiFSI-ethylene carbonate/dimethyl carbonate (4:6, v/v) is charged to 80% capacity in 30 s by using a 120C-constant current/constant voltage charge.