Highly stable lithium-ion battery anode with polyimide coating anchored onto micron-size silicon monoxide via self-assembled monolayer

Silicon monoxide (SiO) with a high Li storage capacity is an attractive material for next-generation lithium-ion batteries. Though, micron-size SiO, which is easier to handle and manufacture, undergoes particle cracking during charge and discharge, leading to fast capacity fading. In this work, we design a robust coating system to accommodate the large volume change of the SiO particles using a self-assembled monolayer (SAM) to covalently bond the active material with a high-modulus polyimide (PI) coating. The SAM is essential as it enhances the adhesion between the particles and the coating, preventing the delamination of the PI coating. The SiO material with the coating demonstrates a stable capacity of 1310.7 mAh g⁻¹ under a current rate of 150 mA g⁻¹ for 100 cycles. The electrode is stable even for 300 cycles at a current rate of 1000 mA g⁻¹. Full cell test with LiFePO₄ positive electrode also shows stable cycle performance with 86% capacity retention after 200 cycles.