Evaluating the efficacy of strategies for silicon/graphite anodes in Li-ion batteries

Abstract

Recent research has been focused on the utilization of silicon (Si) based anode for high-energy-density lithium-ion batteries (LIBs) owing to the high theoretical capacity of Si (similar to 3578 mAh g(-1) ). To mitigate the intrinsic volume change of Si (similar to 300 %) upon cycling, research focused on the co-utilization strategy of Si with graphite anode (SiG) in the form of the blending (physical mixture of Si and graphite) and composite (building up material containing Si and graphite). However, the underlying mechanisms of the two strategies that cause different electrochemical results have not been thoroughly explored. In this study, we aimed to investigate the composite anode (C-SiG-650) and blending anode (B-SiG-650) with a specific capacity of similar to 650 mAh g(-1) in terms of electrochemical performance. The composite anode exhibited a uniform distribution of SiG particles, which helps for faster Li+ ion transport into bulk, whereas the blending anode exhibited aggregation of SiG particles, which impedes the Li+ ion transport into the bulk. As a result, the composite anode exhibited superior capacity retention and rate performance compared to the blending electrode. Moreover, the composite anode containing full-cell delivered a higher specific capacity of 162 mAh g(-1) and capacity retention of 73.58 % after 100 cycles. This implies that directly utilizing composite anode with a low-capacity SiG particle is a promising way to achieve high volumetric energy density for commercial device applications.