Facile synthesis of Co9S8 nanosheets for lithium ion batteries with enhanced rate capability and cycling stability

Two-dimensional Co9S8 nanosheets with a thickness of similar to 10 nm and lateral size of several hundred nanometers are facilely synthesized through a polyvinyl alcohol (PVA)-assisted precipitation process in an aqueous solution. The process has low energy consumption and is easy to scale-up. Compared to the Co9S8 nanoparticles with a diameter of 40 nm prepared through the same process without PVA, the Co9S8 nanosheets, employed as anode materials in lithium-ion batteries, exhibited enhanced rate capability and cycling stability due to their unique two-dimensional nanostructures. When discharging/charging at 1.0 A g(-1), the Co9S8 nanosheets can deliver a reversible capacity as high as 746.8 mA h g(-1) after 300 cycles, which is much higher than that of Co9S8 nanoparticles (63.6 mA h g(-1)), making the Co9S8 nanosheets promising candidates for anode materials in high-energy and high-power lithium ion batteries.