Co2(OH)2CO3 Nanosheets and CoO Nanonets with Tailored Pore Sizes as Anodes for Lithium Ion Batteries.

Co2(OH)2CO3 nanosheets were prepared and initially tested as anode materials for Li ion batteries. Benefiting from hydroxide and carbonate, the as-prepared sample delivered a high reversible capacity of 800 mAh g(-1) after 200 cycles at 200 mA g(-1) and long-cycling capability of 400 mAh g(-1) even at 1 A g(-1). Annealed in Ar, monoclinic Co2(OH)2CO3 nanosheets were transformed into cubic CoO nanonets with rich pores. The pore size had apparent influence on the high-rate performances of CoO. CoO with appropriate pore sizes exhibited greatly enhanced Li storage performances, stable capacity of 637 mAh g(-1) until 200 cycles at 1 A g(-1). More importantly, after many fast charge-discharge cycles, the highly porous nanonets were still maintained. Our results indicate that Co2(OH)2CO3 nanosheets and highly porous CoO nanonets are both promising candidate anode materials for high-performance Li ion batteries.