Electrochemical Properties of Quinone-Based Organic Electrodes in LiCl/DMSO Electrolyte Solutions for Fluorine-Free Lithium Secondary Batteries (Supporting Information)

An organic electrolyte solution of 1.0 mol dm⁻³ LiCl/dimethyl sulfoxide (DMSO) was investigated for a fluorine-free battery with an electrode using 2,5-dimethoxy-1,4-benzoquinone (DMBQ) as the n-type active material and styrene butadiene rubber (SBR) as the binder. The DMBQ electrodes showed the initial discharge capacities of 222 mAh g⁻¹ and 164 mAh g⁻¹ for the DMSO solution of the LiCl system and the LiPF₆ system, respectively. Moreover, they showed similar working voltages of 2.6–2.7 V, even though their plateau slopes had slight differences. In addition, the chemical bonding and crystallinity changes of DMBQ were confirmed during discharge-charge, suggesting that it reacted electrochemically with Li⁺ in the LiCl/DMSO solution. The results of cycle properties suggested that a gradual decrease in the discharge capacities would result from denaturation and dissolution of DMBQ during the redox process in the electrolyte solution.