Interface Engineering Enables Wide-Temperature Li-Ion Storage in Commercial Silicon-Based Anodes

Silicon-based materials have been considered potential anode materials for next-generation lithium-ion batteries based on their high theoretical capacity and low working voltage. However, side reactions at the Si/electrolyte interface bring annoying issues like low Coulombic efficiency, sluggish ionic transport, and inferior temperature compatibility. In this work, the surface Al₂O₃ coating layer is proposed as an artificial solid electrolyte interphase (SEI), which can serve as a physical barrier against the invasion of byproducts like HF(Hydrogen Fluoride) from the decomposition of electrolyte, and acts as a fast Li-ion transport pathway. Besides, the intrinsically high mechanical strength can effectively inhibit the volume expansion of the silicon particles, thus promoting the cyclability. The as-assembled battery cell with the Al₂O₃-coated Si-C anode exhibits a high initial Coulombic efficiency of 80% at RT and a capacity retention ratio up to ≈81.9% after 100 cycles, which is much higher than that of the pristine Si-C anode (≈74.8%). Besides, the expansion rate can also be decreased from 103% to 50%. Moreover, the Al₂O₃-coated Si-C anode also extends the working temperature from room temperature to 0 °C-60 °C. Overall, this work provides an efficient strategy for regulating the interface reactions of Si-based anode and pushes forward the practical applications at real conditions.