LAUSR

Abstract Micro-sized Co(OH)F hexagram-loops were first synthesized through a facile solvothermal method, with poly(vinyl pyrrolidone) (PVP) as a shape-control reagent. The facets ( −3 1 0) and (3 1 0) of Co(OH)F were well preserved by the abduction of PVP. As anodes for lithium ion batteries, the obtained Co(OH)F without any carbon coating delivered a high specific capacity of 642 mAh g−1 at 200 mA g−1 after 200 cycles. Even at a higher rate of 500 mA g−1, a respectable capacity of 470 mAh g−1 was still maintained over 360 cycles. The excellent electrochemical performance is attributed to stepwise lithiation feature and the unique microstructure of Co(OH)F hexagram-loops. The pyramid-like peaks could shorten Li+ ion diffusion distance from all directions, and the large void at the center of loops increases the electrode/electrolyte contact area and buffers volumetric changes upon charge/discharge.