Conductive MOF-Derived Coating for Suppressing the Mn Dissolution in LiMn₂O₄ toward Long-Life Lithium-Ion Batteries

Spinel lithium manganese oxide (LiMn₂O₄, LMO) is a promising cathode material with nontoxicity, high operating voltage, and low cost. However, structural collapse during battery cycling ─ caused by Mn dissolution and the Jahn-Teller effect ─ is a critical disadvantage, reducing cycle retention, particularly at high temperatures. In this study, to solve these critical issues, we introduce Cu₃(HITP)₂ (CuHITP; HITP = 2,3,6,7,10,11-hexaiminotriphenylene), a conductive two-dimensional (2D) metal-organic framework (MOF) as a surface coating material. The CuHITP-derived coating increases the electrical conductivity and suppresses Mn dissolution by enriching the LMO surface with Mn⁴⁺. By suppressing Mn dissolution, structural stability also improves, offsetting the inherent problems. As a result, at 60 °C, CuHITP-LMO exhibits an initial capacity of 95.8 mAh g^-1 at 100 mA g^-1 and achieves a capacity of 42.4 mAh g^-1 after 300 cycles. This research highlights the potential of conductive 2D MOFs to improve the electrochemical performances of LMO.