Poly(benzoquinonyldisulfide) as organic positve electrode for Mg and Li batteries

Abstract

The study of innovative solutions to replace current lithium technology is being carried out at a rapid pace. One of the proposed solution is the development of magnesium batteries, especially organic positive electrode which can exhibit high capacity and capacity retention. In this field, the electrochemical responses of poly(benzoquinonyldisulfide) (PBQDS) in lithium and magnesium cells were investigated in diglyme and sulfolane based electrolytes. Using cavity micro-electrode, similar response was obtained by cyclic voltammetry with the presence of a reversible redox system at 3.5 V vs. Li+/Li or 2.2 V vs. Mg2+/Mg. Using sulfolane + LiTFSI (bis(trifluoromethane)sulfonamide lithium salt) electrolyte, the PBQDS active material achieves a stable capacity of 140 mAh g−1 at C/20. In Mg cell, even if the starting capacity is high, a capacity decrease is noticed along time presumably due to the progressive Mg2+ trapping within the quinone structure. The addition of solvating additive permits to partially mitigate this drawback.