Stable cycling of mesoporous Sn4P3/SnO2@C nanosphere anode with high initial coulombic efficiency for Li-ion batteries

Tin dioxide is one promising anode due to its high-capacity of conversion-reaction during lithiation. However, its applications are often hindered by its low initial Coulombic efficiency caused by irreversible Li2O formation and huge volume expansion during lithiation. Here, we synthesized Sn4P3/SnO2 hollow nanospheres in carbon matrix as anode materials for lithium-ion batteries. The in-situ phosphorization of SnO2 promotes the initial Coulombic efficiency to ~77% with a high capacity of 975 mA h g−1. Moreover, it exhibits an excellent rate performance of 713 mA h g−1 at 2 A g−1. Using in-situ transmission electron microscopy, its volume increase was closely monitored to be only ~84.8% (largely improved compared with over 200% increase for SnO2) during the first lithiation and Sn4P3/SnO2@C can maintain structural integrity and form a stable SEI layer. Our approach is low-cost and simple enough for large-scale manufacture and can be widely applied to other oxide anodes to enhance its performance through phosphorization and forming composite with conductive carbon matrix.