Si Microparticles Embedded within Wrinkled-Multilayered-Graphenes for High-Areal-Capacity Lithium-Ion Batteries

Even nanostructured Si electrodes have demonstrated stable electrochemical performances in lithium-ion batteries (LIBs), complex process and high-cost of nanostructured Si electrodes are far from industry standards. Thus, utilization of commercially available low-cost Si microparticles with high-performance is highly necessary for high-energy-density LIBs. In this presentation, we demonstrate a simple and scalable method to utilize commercially available Si microparticles (<i>ca.</i> 7 μm) with wrinkled-multilayered-graphenes (Si-WMGs) for high-areal-capacity LIBs. The WMGs provide not only mechanical flexibility for mitigating large volume change of Si microparticles during deep charge/discharge processes, but also good adhesion property to effectively coalesce Si microparticles, and high electrical conductivity, resulting in binder- and conductor-free thick electrodes. The Si-WMG electrodes showed high initial areal capacities of 12.5 mAh cm^-2 at 0.1 C and 7.1 mAh cm^-2 even at a very high rate of 2 C, with outstanding long-term stability with 5.3 mAh cm^-2 at 2 C for over 240 cycles. Furthermore, a full cell composed of Si-WMG and lithium cobalt oxide presented 3.13 mAh cm^-2 and a stable cycling performance (90.3% retention after 100 cycles) in a practical cell setting, clearly demonstrating the practical applicability of Si-WMG electrodes. Therefore, the WMG as a binder and conductor could be applicable to other electrodes with a large volume change and high mass-loading for high-areal-capacity LIBs.