Mechanofusion-derived Si-alloy/graphite composite electrode materials for Li-ion batteries

Silicon-graphite composites are extremely promising negative electrode materials for Li-ion batteries. However, simple and effective methods to synthesize silicon-graphite composites with engineered structures are needed to realize this technology in practical applications. Here, we show that the environmentally friendly and low-cost dry mechanofusion (MF) process can effectively synthesize silicon alloy-graphite composites, in which silicon alloy particles can be well dispersed and embedded between graphite layers. This results in increased tap density and reduced surface area. The special structure provides a way to buffer volume expansion and contraction of the silicon alloy during lithiation and delithiation. As a result of this hierarchical arrangement, superior cyclability and rate capability are achieved compared to simple mixtures, with capacities of 950 mA h g(-1) (i.e. 1473 A h L-1) and 900 mA h g(-1) (i.e. 1432 A h L-1) at 2C and 4C, respectively.