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

Co-2(OH)(2)CO3 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 Co-2(OH)(2)CO3 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 Co-2(OH)(2)CO3 nanosheets and highly porous CoO nanonets are both promising candidate anode materials for high-performance Li ion batteries.