MnCo2O4 nanospheres for improved lithium storage performance

摘要

Mesoporous MnCo2O4 nanospheres with an average diameter of approximately 480 nm have been synthesized by a polyvinyl pyrrolidone (PVP)-assisted solvothermal method followed by thermal annealing. MnCo2O4 nanospheres consist of many nanoparticles having sizes in range of 20-50 nm, the specific area of the sample being 24.4 m(2) g(-1). When used as the anode material for lithium ion batteries, the mesoporous MnCO2O4 nanospheres show not only an excellent cycling stability, but also an outstanding rate capability. More specially, the discharge capacities of 749.1 and 629.6 mA h g(-1) can be retained at current densities of 200 and 400 mA g(-1) after 50 cycles, respectively. In addition, the average discharge capacities of 1013.8, 827.1, 770.6, 733.3, 697.3, 651.4 and 522.4 mA h g(-1) could be observed at current densities of 100, 200, 400, 600, 800, 1000 and 2000 mA g(-1), respectively. The improved cycling stability and rate capability can be ascribed to two unique structural features of mesoporous MnCo2O4 nanospheres: namely, the mesoporous nature of electrode materials which can help to reduce the volume variation during repeated lithiation/delithiation processes, and the nanostructure which can provide a shortened Li+ transmission path. The current synthesis approach can be easily spread to prepare other binary metal oxides, including Co-free anode materials.