MOF-Derived CuS@Cu-BTC Composites as High-Performance Anodes for Lithium-Ion Batteries

The CuS(x wt%)@Cu-BTC (BTC = 1,3,5-benzenetricarboxylate; x = 3, 10, 33, 58, 70, 99.9) materials are synthesized by a facile sulfidation reaction. The composites are composed of octahedral Cu₃ (BTC)₂ ·(H₂ O)₃ (Cu-BTC) with a large specific surface area and CuS with a high conductivity. The as-prepared CuS@Cu-BTC products are first applied as the anodes of lithium-ion batteries (LIBs). The synergistic effect between Cu-BTC and CuS components can not only accommodate the volume change and stress relaxation of electrodes but also facilitate the fast transport of Li ions. Thus, it can greatly suppress the transformation process from Li₂ S to polysulfides by improving the reversibility of the conversion reaction. Benefiting from the unique structural features, the optimal CuS(70 wt%)@Cu-BTC sample exhibits a remarkably improved electrochemical performance, showing an over-theoretical capacity up to 1609 mAh g^-1 after 200 cycles (100 mA g^-1 ) with an excellent rate-capability of ≈490 mAh g^-1 at 1000 mA g^-1 . The outstanding LIB properties indicate that the CuS(70 wt%)@Cu-BTC sample is a highly desirable electrode material candidate for high-performance LIBs.