NiCo2O4 nanosheets and nanocones as additive-free anodes for high-performance Li-ion batteries

Development of novel electrode materials with high energy and power densities for lithium-ion batteries (LIBs) is the key to meet the demands of electric vehicles. Transition metal oxides that can react with large amounts of Li+ for electrochemical energy storage are considered promising anode materials for LIBs. In this work, NiCo2O4 nanosheets and nanocones on Ni foam have been synthesized via general hydrothermal growth and low-temperature annealing treatment. They exhibit high rate capacities and good cyclic performance as LIB anodes owing to their architecture design, which reduces ion and electron transport distance, expands the electrode-electrolyte contact, increases the structural stability, and buffers volume change during cycles. Notably, NiCo2O4 nanosheets deliver an initial capacity of 2239 mAh g(-1) and a rate capacity of 964 mAh g(-1) at current densities of 100 and 5000 mA g(-1), respectively. The corresponding values of nanocones are 1912 and 714 mAh g(-1). Hence, the as-synthesized NiCo2O4 nanosheets and nanocones, which are carbon-free and binder free with higher energy densities and stronger connections between active materials and current collectors for better stability, are promising for use in advanced anodes for high-performance LIBs.