Surface engineering on silicon based anode material for Li ion batteries

Battery Science & TechnologyThe exhaustion of traditional energy and the deterioration of environment have been seriously hindering social development and daily life, especially transportation. Exploring more efficient and environmentally-friendly power devices has attracted tremendous attention in the recent 50 years. Among various devices, lithium-ion batteries (LIBs) have been considered the most promising one, in terms of high voltage, large specific capacity, and environmental friendliness. Accordingly, the LIBs are being extensively applied in growing diversities from laptops to hybrid electric vehicles (HEVs) and electric vehicles (EVs). However, the current LIB technology cannot satisfy the evergrowing demand for high-performance power sources. That is why many researchers have been exploring advanced materials including cathodes, anodes, and electrolytes to pursue higher energy and power density, longer life, and lower cost. Si, Sn, alloys, and MnXm-type compounds (where M = Fe, Co, Ni, Cu, Sn, etc., while X = O, S, N, etc.) are investigated as anode materials. Though all these active materials show considerable capability and promising prospects, many obstacles restrict their commercialization, including poor electronic conductivity, low Li+ transfer efficiency, volume expansion/contraction during repeated cycling processes, and loss of active materials due to the corrosion of electrolytes or/and collapse of the stable structure. To overcome these troublesome obstacles, researchers have proposed various feasible strategies, such as optimizing the crystalline lattice of active materials by doping cations or anions, reducing particles to a suitable scale to offer enhanced electron/ Li+ conductivity and reactivity, combining active materials and other active/inactive materials together for complementary strengthening, especially surface coating and core–shell structures. In this study, we researched carbon-silicon composites and TixSiy-coated Si for anode materials. These enhanced electrochemical performances were compared with bare carbon and bare silicon. These synthetic approaches open up a way to make other composites of anode materials for high performance LIBs.ope