Green and scalable preparation of disproportionated SiO anode materials with cocoon-like buffer layer

Abstract

Silicon is regarded as the most promising candidate for the next-generation anode materials, because of its high specific capacity and wide availability. However, silicon anode materials suffer from large volume change during the charging/discharging processes, which leads to a too fast capacity degradation. To alleviate the volume change and capacity degradation, preforming pore structure in silicon anode materials is the most frequently adopted strategy. The pores are usually formed either by using templates or through selective etching, which involves complicated preparation process and consumes hazard chemicals. Here, we propose a nanostructured silicon anode derived from low-cost raw materials without the use of templates. The composite is composed of dense active cores and fluffy cocoon-like buffer layer. The buffer layer is a network of carbon nanobelts, which accommodates the volume change and maintains the electrical contact during the charging/discharging processes. As a result, the porous composite with the buffer layer displays a high cyclability, with a capacity retention of 104% after 100 cycles, while the dense sample without the buffer layer has a capacity retention of only 36%. Moreover, the process is green, effective and scalable, which could promote the application of silicon based anode materials.