Mesoporous single-crystalline MnO_x nanofibers@graphene for ultra-high rate and long-life lithium-ion battery anodes

With the increasing energy demand of electronic devices and electric vehicles, the achievement of anode materials for lithium-ion batteries with high specific capacity and superior rate capability and cycling stability still remains a challenge. Herein, we report a novel strategy to prepare the core-shell mesoporous single-crystalline MnO_x nanofibers@graphene (PSCMnO_x@G) through a “spraying-rapid freezing” process. The elastic graphene shell not only improves the conductivity of the electrode but can also substantially inhibit the collapse of MnO_x nanofibers (NFs) over continuous discharge-charge cycles. Moreover, the double-exchange interaction of manganese mixed-valence ions further improves the conductivity of manganese oxide, and Li ion diffusion is significantly enhanced by the vertically aligned single-crystalline and mesoporous structure of MnO_x NFs. As a result, the PSCMnO_x@G exhibits an ultrahigh rate performance (1072 mA h g⁻¹ at 0.1 A g⁻¹ and 419 mA h g⁻¹ at 10 A g⁻¹), which is among the best ever reported for MnO_x based anodes, as well as excellent cycling stability (1162 mA h g⁻¹ at 2 A g⁻¹ over 500 cycles).