Optimizing Silicon Nanostructures for Enhanced Li-Ion Storage: Microstructure, Binder and Production Technology

Abstract

The utilization of silicon nanostructures as anodes in lithium-ion batteries (LIBs) presents a promising avenue for improving device performance. However challenges related to prolonged cycling, energy density, and costs need to be addressed. This presentation outlines three strategies employed within the E2MC framework to overcome these challenges: (a) By incorporating high-quality graphene nanosheets, produced through a low-cost and scalable molten salt method, common silicon nanoparticles (generated by commercially available pyrolysis-based methods) can be enveloped in graphene layers with a controllable chemical composition. The graphene-encapsulated silicon nanoparticles exhibit stable electrochemical lithiation/delithiation performance, showcasing significantly improved energy density, even after numerous Li-insertion and extraction cycles, outperforming bare Si nanoparticles; (b) Thermally modified polyimide (PI) is introduced as an efficient binder to enhance the Li-ion storage performance of silicon nanoparticles. An optimized thermal treatment of the electrodes containing Si nanoparticles and PI binder produces an effective charge transfer complex (CTC) structure, improving the electrochemical performance by forming a compact structure that reduces charge transfer impedance. This enhancement significantly boosts the cycling performance of the silicon anode; (c) An ultra-fast shock-wave combustion synthesis approach is introduced for the rapid and low-cost preparation of Si nanostructures using naturally available SiO2 as the silicon feedstock. Completed at an ignition temperature of approximately 550 °C, this method requires virtually no dwell time. The resulting nanostructured Si product exhibits a mesoporous integrated sheet-like morphology, demonstrating excellent and stable Li-ion storage performance. This approach contributes to a more sustainable and cost-effective utilization of elemental Si nanoparticles in LIB applications.