Lithium Benzenedithiolate Catholytes for Rechargeable Lithium Batteries

Abstract Organic electrode materials have become a vibrant area of research. Lithium benzenedithiolate (LBDT) consists of two –SLi groups that could donate 2Li⁺ and 2e⁻ in oxidation reactions, thus being a potential high‐capacity organic cathode material for rechargeable lithium batteries. Herein, 1,2‐, 1,3‐, and 1,4‐LBDTs are investigated to elucidate the relationship of their redox chemistry and effect of lithium thiolate position on their electrochemical behavior experimentally and theoretically. High‐performance liquid chromatography in tandem with quadrupole time‐of‐flight mass spectrometry is used, for the first time, to separate and identify the charge and discharge products of these compounds in lithium batteries. During the charging process, 1,2‐, 1,3‐ and 1,4‐LBDTs are mainly converted to the cyclic dimer, trimer, and tetramer respectively. While in the discharge process, the initial lithiated materials are recovered. The cyclic dimer of 1,2‐LBDT shows the lowest discharge overpotential and fast kinetics, which are related to the easiness of the 2nd lithiation process. It delivers an initial specific capacity of 340 mAh g⁻¹ and retains 84.1% of the initial capacity over 100 cycles at C/2 rate. In addition, it shows much better rate capability than the other two LBDTs. The structure–performance relationship of LBDT in lithium batteries is correlated.