Enabling Fast-Charging and Enhanced Cycling Stability of Graphite Anode for Li-Ion Batteries with a Low-Cost Nano-Silica Electrolyte Additive

Graphite has been widely used in lithium-ion batteries. However, it suffers from reduced stability and poor reaction kinetics observed during long-term cycling. In this study, nano silicon dioxide (SiO₂) was employed as an additive to enhance the rate capability and long-cycle performance of graphite electrodes. Theoretical calculations, electrochemical and structural investigations suggest that the additive not only enhances the ionic conductivity and Li⁺ transference number of the electrolyte but also alters the solvation structure at the graphite and electrolyte interfaces to promote the formation of a fluorine-rich solid electrolyte interphase (SEI). In addition, it eliminates the trace water-generated HF to mitigate side reactions. These improvements enhance the structural stability and reaction kinetics of the graphite electrode. Electrochemical performance evaluation reveals outstanding stability of the modified graphite||lithium cell, which retains 98% of its initial capacity after 400 cycles at 0.1 A g^-1. Remarkably, even under high-rate cycling at 2 A g^-1, the cell still delivers a substantial capacity of 150 mAh g^-1 following 1,000 cycles. The modified electrolyte enables graphite stable operation even at 0 and 60 °C. In graphite||LiFePO₄ full cell with high mass loading, the capacity retention reaches 81.3% after 300 cycles at a low current density of 0.1 A g^-1, significantly outperforming the cell with baseline electrolyte. This study presents a simple and efficient strategy for designing electrolytes that enable graphite-based lithium-ion batteries to achieve fast charging/discharging and long-term stable cycling.