High energy storage MnO2@C fabricated by ultrasonic-assisted stepwise electrodeposition and vapor carbon coating

A new structure of MnO2 was designed by ultrasonic-assisted step-by-step electrodeposition on the three-dimensional porous nickel foam skeleton, and a simple carbon coating was designed to further improve the conductivity and stability of the electrode material, and apply it as a self-standing electrode without binder or conductive agent (P-C-MnO2@C). This electrode material has two different morphologies of nanorods and nanosheets, and the unique structure realizes fast transportation kinetics, which is conducive to high-capacity and fast Li+ and Na+ storage. Carbon coating significantly improves the conductivity of the material and can alleviate the volume change of MnO2 during ion insertion/extraction. P-C-MnO2@C has high capacity, rate performance and cycle performance in both supercapacitors (340 F g−1 at 20 A g−1) and lithium-ion battery anodes (1181 mAh g−1 after 500 cycles at 1 A g−1), indicating that it is a promising energy storage material.