Halide Ion Intercalated Electrodeposition Synthesis of Co₃O₄ Nanosheets with Tunable Pores on Graphene Foams as Free-Standing and Flexible Li-Ion Battery Anodes

Soft portable electronics has grabbed the attention of manufacturing industry. One of the issues is the flexible energy sources with high energy density, high operating voltage, and long lifetime. Flexible lithium ion batteries could be the solution. However, the conventional electrode production process is paste casting which contains binder, conductive additive, and substrates with no capacities and limits the flexibility of lithium ion batteries. Herein, we promote the electrode preparation by halide ion intercalated electrodeposition of Co(OH)2 nanosheet precursors on graphene foams. The Co3O4/graphene foam electrodes, the final product, exhibit good flexibility and mechanical strength. Meanwhile, by regulation of the ratio of Br– and Cl–, specific surface areas, pore volumes, pore diameters, and specific capacities can be modified with the highest specific capacity of 790 mA h g–1 after 100 cycles at a current density of 0.1 C in the voltage range of 0.2–3.0 V. Furthermore, because of the similar particle sizes of porous Co3O4 nanosheets, the influence of pore nature on the electrochemical performance is revealed. A full cell is assembled to testify the good electrochemical performance of porous Co3O4/graphene foam electrode.