Recycled micro-sized silicon anode for high-voltage lithium-ion batteries

Silicon (Si) anode is widely viewed as a game changer for lithium-ion batteries (LIBs) due to its much higher capacity than the prevalent graphite and availability in sufficient quantity and quality. Most Si anode designs are nanostructured to overcome the large volume variation during cycling, but this comes at the expense of manufacturability, cost advantage and other merits. Here we demonstrate that micro-sized Si (μm-Si) recycled from photovoltaic waste can serve as anode material, exhibiting an average Coulombic efficiency of 99.94% and retaining 83.13% of its initial capacity after 200 cycles through the rational electrolyte design. With a formulated ether electrolyte of 3 M LiPF6 in 1,3-dioxane (DX)/1,2-diethoxyethane (DEE), NCM811||μm-Si pouch cells survive 80 cycles and deliver an energy density of 340.7 Wh kg−1 even under harsh conditions. Responsible for the impressive electrochemical performance is a unique SEI chemistry where the flexible polymer-dominated outer layer well holds fractured Si particles together and the rigid Li2O/LiF-rich inner layer serves to facilitate ionic conduction and suppress side reactions. Our work not only suggests a more sustainable supply source for Si particles but also addresses the major problems facing μm-Si anode materials.