High rate and high capacity lithiation of rGO-coated Co2(OH)2CO3 nanosheet arrays for lithium-ion batteries through the involvement of CO32−

RGO-coated Co2(OH)2CO3 nanosheet arrays, mixed with a few CoO nanowires, were synthesized and deposited on copper foil directly via a simple one-step hydrothermal procedure. Benefited from its unique chemical composition and spatial structure, the obtained samples exhibited high performance as anode material for Lithium ion batteries, which delivered a very high reversible capacity of 2,100 mAh g−1 at 100 mA g−1 after activation and even as high as 1,240 mAh g−1 at a much higher charge/discharge current of 5000 mA g−1. Additionally, the composite electrode exhibited a high cycling stability, 85% of the initial capacity was remained after 100 cycles test at 1,000 mAh g−1. HRTEM analysis indicated that CO32− was involved into the energy storage process, which should be the key factor of such high capacity, while the covered layer of rGO and the synthesis route of directly deposition were suspected to play very important roles on the high stability and high power density.