Towards high-capacity lithium ion batteries:constructing hollow-structured SiOx-based nanocube anode via a sequential coating strategy

Reserving void space for silicon oxide-based (SiOx-based) anodes has proved highly efficient in tackling their volume expansion and contraction upon lithiation/delithiation. Specially, hollow structure featured with sufficient internal spaces shows great promise in buffering the volumetric effect of SiOx. However, constructing a hollow structure, containing high-capacity SiOx components and high-conductivity carbon components, still remains a great challenge. In this work, we design a sequential coating strategy to initially construct sandwich hollow-structured high-capacity SiOx anode (NC@SiOx@m-C) that consists of an innermost nitrogen-doped porous carbon network (NC), a middle mesoporous SiOx layer, and outermost mesoporous carbon (m-C) layer. The incorporation of high-capacity component SiOx (x < 2) via sequential coating process greatly improves the specific capacity of NC@SiOx@m-C. Both of NC and m-C layers synergistically enhance the overall electronic conductivity of the anode. Moreover, the outermost m-C layer retards the direct contact between SiOx and electrolyte and effectively reduces the side reactions. As a result, the NC@SiOx@m-C nanocubes delivers a capacity as high as 583 mAh g-1 at a high current density of 1 Ag-1 after 500 cycles, giving an excellent electrochemical performance.

Automated summary

In this work, a sequential coating strategy was employed to construct a hollow-structured high-capacity SiOx anode, which consisted of an inner nitrogen-doped porous carbon network, a middle mesoporous SiOx layer, and an outer mesoporous carbon layer. The incorporation of high-capacity SiOx via sequential coating significantly improved the specific capacity, while the carbon layers enhanced the electronic conductivity and reduced side reactions. The resulting nanocubes exhibited excellent electrochemical performance, delivering a high capacity even after 500 cycles at a high current density.