Inverse design and high-throughput screening of TM-A (TM: Transition metal; A: O, S, Se) cathodes for chloride-ion batteries

Abstract

Transition metal oxychlorides (TMOCl) are one of the most attractive cathode materials for chloride ion batteries (CIBs) due to their layered framework and high stability in organic electrolytes. However, the conversion reaction of TMOCl at low Cl− content is harmful to the cycle performance and energy density of CIBs. In order to eliminate the conversion reaction, high-throughput screening combined with an inverse design method is applied to search Cl-free layered materials among the TM-A (A = O, S, Se) compounds. After a comprehensive evaluation of layered characteristics, thermodynamic and dynamic stability, FeSe and its chloride FeSeCl are found to both have layered ground state structures. The stable Fe-Se framework prevents the material from decomposing or reconstructing during Cl− extraction. Compared to the reported TMOCl cathodes, the discharge process from FeSeCl to FeSe is a constant intercalation reaction, which leads to a flat voltage platform, high reaction reversibility, and low reaction energy barrier. The extended Se-4p orbital ensures excellent electronic conductivity. In addition, the spacious Cl− channels in FeSeCl and FeSe result in low Cl− diffusion barriers of 0.28 and 0.13 eV, respectively, which is significantly improved compared to the reported TMOCl materials.