Enhancing Lewis acidic/basic activities of silicon anodes via amine-bridged polymeric copper phthalocyanines for high-performance lithium-ion batteries

Abstract

Silicon (Si) is one of the most promising anode materials for high-energy-density lithium-ion batteries (LiBs) due to its extremely high theoretical capacity (4200 mAh g⁻¹) as well as natural abundance. However, drastic volume changes of Si particles upon lithiation/de-lithiation cause severe electrode pulverization and interfacial side reactions, hindering the practical adoption of Si anodes. Herein, the intrinsic challenges of Si anodes are efficiently addressed by enriching Lewis acidic/basic activities of Si particles. The interfacial chemistry regulation strategy applied herein capitalizes on the use of amine-bridged polymeric copper phthalocyanines (CuPPc-NH) as an artificial solid-electrolyte interphase (SEI) layer on Si particles. To be specific, CuPPc-NH contains both Lewis acidic and basic interactive sites, each of which can promote the decomposition of PF₆⁻ and strongly chemisorb Li⁺, respectively. As a result, CuPPc-NH-coated Si (CuPPc-NH@Si) facilitates the formation of a salt-derived SEI enriched with LiF and accelerates Li⁺ transport kinetics. Moreover, amine functional groups within CuPPc-NH can form hydrogen bonds with conventionally used poly(acrylic acid) binders, forming a robust interconnected network to improve the structural integrity of the CuPPc-NH@Si anode. These beneficial attributes directly translate into remarkable full-cell performances with both LiFePO₄ and LiNi_0.8Co_0.1Mn_0.1O₂ cathodes at practical N/P ratios.