Lithium copper/manganese titanate anode material for rechargeable lithium-ion batteries

Abstract

In this article, Cu2+ and Mn2+ are chosen as divalent metal cations to dope and synthesize Li2MTi3O8 (M = Cu, Mn, Cu0.5Mn0.5) by a simple solid state reaction route. The structures of Li2MTi3O8 (M = Cu, Mn, Cu0.5Mn0.5) are proved by Rietveld refinement method for the first time. Due to different divalent metal cations M2+ in the structure, Li2MTi3O8 exhibits different electrochemical performances. Li2CuTi3O8 shows the highest initial charge capacity of 242 mAh g−1 and Li2MnTi3O8 displays the lowest initial charge capacity of 139.5 mAh g−1 among all the three samples. Although Li2Cu0.5Mn0.5Ti3O8 reveals a lower initial charge capacity of 174.5 mAh g−1, it exhibits better cycle performance than Li2CuTi3O8 and Li2MnTi3O8. Li2Cu0.5Mn0.5Ti3O8 keeps the reversible capacity of 143 mAh g−1 after 50 cycles at 100 mA g−1 with capacity retention of 82.2%. Besides, the results of electrochemical impedance spectra indicate that lithium ion can move easily in the tunnels of three-dimensional network formed by the (Li0.7Cu0.15Mn0.25)tet, which is in agreement with the result that Li2Cu0.5Mn0.5Ti3O8 performs better electrochemical properties than Li2CuTi3O8 and Li2MnTi3O8. It provides a possibility and theoretical support to synthesize Ti-based materials Li2MTi3O8 with good electrochemical performances.