Mesoporous single-crystalline MnOx 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 MnOx nanofibers@graphene (PSCMnOx@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 MnOx 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 MnOx NFs. As a result, the PSCMnOx@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 MnOx based anodes, as well as excellent cycling stability (1162 mA h g(-1) at 2 A g(-1) over 500 cycles).