Enhanced Lithium Storage in Micro-Si-Based Anode Materials through Low-Temperature Interface Engineering with an Ultrathin Phenolic Interlayer

Silicon (Si) anode materials show tremendous potential for high-energy Li-ion batteries (LIBs) due to their excellent theoretical capacity. However, critical issues like initial capacity loss, unstable solid electrolyte interface (SEI) formation, and volume changes during cycling have hindered their practical application. To address these challenges, we have developed a resilient Si interface for rapid Li+ ion transport while maintaining Si structural integrity. Herein, we utilized microsized porous silicon (m-PSi) coated with an ultrathin phenolic interlayer from low-temperature thermolysis of poly­(4-vinylphenol) (PVP). This PVP-derived phenolic carbon is covalently linked to the Si surface, creating a strong Si interface and a pathway for Li+ ion transport. The grafted m-PSi (m-GPSi) anode shows an impressive initial capacity of 3134 mA h g–1 with a capacity retention of 80.0% after 100 cycles at 0.1 A g–1. Moreover, it demonstrated a superior rate performance of 1270 mA h g–1 at 4 A g–1 with a recovery rate of 96% at 0.1 A g–1. These results surpass state-of-the-art microsized Si anodes, primarily due to the covalently interfaced ultrathin phenolic interlayer, consequently enhancing Li+ ion conductivity, mechanical strength, and stable SEI formation during the LIB operation. This research offers a convenient interface engineering strategy to enhance the Si anode performance for next-generation LIBs.