Rechargeable organic lithium-ion batteries using electron-deficient benzoquinones as positive-electrode materials with high discharge voltages

Abstract

Organic rechargeable lithium-ion batteries have great potential to overcome the various problems of current inorganic battery configurations. Although organic quinone-type positive-electrode materials have been previously applied in batteries, their inferior voltage output compared to those using LiCoO₂ signifies the need for further development. Thus, we focused on raising the voltages from benzoquinone derivatives through the use of structural diversity. Electron-deficient benzoquinones bearing perfluoroalkyl groups were prepared and evaluated as cathode active materials in rechargeable batteries. The cells exhibited higher voltage plateaus in their charge–discharge curves compared to those using electron-rich benzoquinones, indicating an increased voltage as a result of the electron-withdrawing groups in the benzoquinone skeleton. The perfluoroalkylated benzoquinones effectively worked as positive-electrode materials, with improved charge–discharge cycle performance in the cells due to the stability of the benzoquinones toward decomposition during cycling. DFT calculations performed to explore the reasons behind this stability revealed that Li–F interactions stabilized the radical and dilithium-salt intermediates of benzoquinone reduction. Electrolyte effects on the charge–discharge performance were also examined in the trifluoromethylated system, revealing a significant impact on the shape of the discharge curves and the cycle-life performance.