A Stable Copper‐Organosulfide Cathode for Rechargeable Lithium Batteries

ABSTRACT Organosulfides have been considered as promising alternative materials for sulfur‐based cathodes due to their strong structural tailorability, abundant redox‐active sites. However, general organosulfides suffer from low conductivity, high solubility in electrolyte, which leads to low active materials utilization, severe shuttle effects, and short cycling life. Metal‐organosulfide complexes, which can be formed by reactions between thiol groups in aromatic organosulfides and transition metal ions, feature π‐d conjugated frameworks with improved conductivity and are insoluble in general electrolytes. These features offer a possible strategy to overcome bottlenecks of organosulfides at the molecular level. Herein, a small molecule PhSCu is selected as the cathode material for rechargeable lithium battery and the electrochemical behaviors were explored systematically. X‐ray photoelectron spectroscopy (XPS), high performance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (HPLC‐QTof‐MS), and Fourier transform infrared spectroscopy (FTIR) analyses reveal the reversible valence transition of Cu/Cu + accompanied by reversible Cu─S bond cleavage and reformation during charge and discharge processes. The Li||PhSCu cell delivers an initial capacity of 152.6 mAh g −1 and retains a capacity of 117.7 mAh g −1 after 140 cycles. The study aims to provide a guidance for addressing the dissolution issue of organosufide cathodes in alkali metal batteries.