Research progress on the preparation of silicon-based anode materials for lithium batteries from industrial waste

Silicon is regarded as one of the most promising anode materials for next-generation lithium-ion batteries (LIBs) due to its exceptionally high theoretical specific capacity, moderate operating potential, and abundant natural reserves. However, the commercial application of silicon anodes is severely hampered by inherent drawbacks, such as low electrical conductivity, sluggish lithium-ion diffusion kinetics, and enormous volume expansion (>300%) during lithiation/delithiation. These issues lead to electrode pulverization, repeated fracture and reformation of the solid electrolyte interphase (SEI) layer, accelerated electrolyte consumption, and rapid capacity fading. To address these challenges, various modification strategies have been developed, including nanostructuring, structural engineering, carbon compositing, and elemental doping. Among these, the choice of silicon source plays a critical role in determining both performance and cost. Compared with biomass- or gaseous-derived silicon sources, industrial silicon waste-such as photovoltaic cutting waste, decommissioned modules, discarded wind turbine blades, and silica fume-offers advantages including high silicon content, low cost, and wide availability. Its utilization enables waste valorization, providing a green and economical feedstock for high-performance silicon anodes. This review systematically summarizes recent progress in fabricating silicon-based anodes from industrial silicon waste, covering the sources and characteristics of typical waste streams, pretreatment techniques, shaping processes, structural design, and synergistic modification effects. Photovoltaic cutting waste and decommissioned modules are particularly suitable for preparing silicon-carbon anodes due to their particle size and structure, which simplify processing and reduce costs. Pretreatment primarily includes physical separation, wet acid leaching (to remove metals such as Fe and Al), pyrometallurgical refining (to eliminate oxygen, boron, and phosphorus), and molten salt electrolysis. We propose a selective lightweight pretreatment strategy that removes only catalytically active impurities while moderately retaining and tuning the oxide layer, achieving a balance among purity, reactivity, safety, and cost. In terms of shaping processes, three representative techniques are discussed in detail. Vacuum solid?state reaction converts silicon and silica into silicon monoxide at temperatures above 1250?°C, achieving a conversion yield exceeding 95% when using cutting waste. Ball milling or bead milling refines silicon particles to below 150?nm and enables in?situ compositing with carbon precursors, leading to stable cycling performance. Rapid thermal treatment, particularly flash Joule heating, achieves extreme heating and cooling within milliseconds with nearly 100% energy efficiency, enabling the preparation of unique nanostructures such as silicon nanowires and core?shell architectures. Structural design is key to mitigating volume expansion. One?dimensional nanowires offer high flexibility and strain relaxation capability; two?dimensional nanosheets provide abundant active sites and anisotropic Li-ion diffusion pathways; three-dimensional core-shell, yolk-shell, and sandwich structures effectively buffer volume expansion. Porous silicon, prepared via magnesiothermic reduction or metal-assisted chemical etching, features interconnected pore networks that relieve stress and accelerate ion transport. Carbon compositing (with soft carbon, hard carbon, graphite, graphene) and elemental doping (with N, F, P, B, Ag, Sn, etc.) further enhance electrical conductivity and interfacial stability. Finally, we highlight current challenges, such as precisely balancing impurities and the oxide layer during pretreatment, scaling up rapid thermal treatment processes, and navigating trade?offs between structural complexity and initial Coulombic efficiency/energy density. Future research should focus on green, short?process technologies, precise structural engineering, and synergistic multi-strategy design, integrated with life-cycle assessment to achieve a closed-loop circular economy. Industrial silicon waste provides a viable pathway toward low-cost, high-performance, and sustainable silicon anode materials.