Recycled solar-grade silicon kerf scraps and sandwiched by tunable porous carbon sheets as commercial anodes

Abstract

To commercialize silicon/carbon (Si/C) anodes easy, the solar-grade silicon kerf scraps (SGSKS) abandoned from photovoltaic industry are purified and recycled as a cost-efficient silicon source for lithium storage. However, limited by commercial cathodes, pursuing good structural integrity and durable lifespans is more worthy of concern than super-high capacity for commercial Si/C anodes which is primarily impacted by silicon mass fraction and volume vibration tolerance. Hence, controlling silicon mass loading and providing sufficient void spaces for volume vibration are significant for the high-grade Si/C anodes. Herein, a highly-tunable and facile synthesis approach for Si/C composite sandwiched by porous carbon sheets (PCS/Si) is described using flake-like CaCO3 as template and SGSKS as raw materials. Through regulating the mass ratio of CaCO3 and silicon, it can effectively control silicon mass loading and void spaces in PCS/Si for strengthening structural integrity, prolonging lifespans, simultaneously achieving sufficient capacity to meet commercial demands. The experimental findings demonstrate that benefitting from this deliberate design, the optimized PCS/Si-2 composite with silicon mass loading of 30.62 wt% delivers a high-profile capacity retention of 853.4 mAhg(-1) at 0.2 Ag-1 with a relatively good structural integrity. Moreover, full cells using PCS/Si-2 anodes matched with commercial LiCO2 cathodes exhibit a long-cycle steady capacity of 103.4 mAhg(-1) at 0.2 C which also can light a row of LED bulbs for hours, facilitating a rosy potential for commercial application. Meanwhile, it offers an alternative and valuable viewpoint for high-value recycle and reutilization of photovoltaic waste, promoting resource conservation and environment protection.