Electrophoretic Deposition of Binder-Free MnO2/Graphene Films for Lithium-Ion Batteries

Binder-free, nano-sized needlelike MnO2-submillimeter-sized reduced graphene oxide (nMnO2-srGO) hybrid films with abundant porous structures were fabricated through electrophoretic deposition and subsequent thermal annealing at 500 °C for 2 h. The as-prepared hybrid films exhibit a unique hierarchical morphology, in which nMnO2 with a diameter of 20—50 nm and a length of 300—500 nm is randomly anchored on both sides of srGO. When evaluated as binder-free anodes for lithium-ion half-cell, the nMnO2-srGO composites with a content of 76.9 wt% MnO2 deliver a high capacity of approximately 1652.2 mA•h•g−1 at a current density of 0.1 A•g−1 after 200 cycles. The high capacity remains at 616.8 mA•h•g−1 (ca. 65.1% capacity retention) at a current density as high as 4 A•g−1. The excellent electrochemical performance indicates that the nMnO2-srGO hybrid films could be a promising anode material for lithium ion batteries (LIBs).