Metallurgical refractory lining-guided inorganic binder for stable lithium storage in silicon microparticle anodes

Abstract

Silicon is a promising anode material for next-generation lithium-ion batteries (LIBs), offering a significantly higher theoretical capacity than graphite. While nano-silicon excels, its high cost limits practicality, making silicon microparticles (μSi) a more economical, scalable alternative. However, μSi anodes are hindered by substantial capacity degradation, resulting from the over 300% volume expansion during cycling. This study introduces an aluminum dihydrogen phosphate (Al(H2PO4)3, AHP) binder system, designed based on principles of refractory chemistry, which effectively mitigates interfacial instability and mechanical failures in μSi anodes. The water-soluble AHP binder forms a uniform electrode through in situ dehydration condensation, creating a covalently cross-linked inorganic network. This high-modulus cross-linked network restricts the expansion of μSi particles during cycling, thereby preserving electrode integrity. As a result, μSi anodes incorporating the AHP binder exhibit exceptional cyclability, retaining a capacity of 1300.4 mAh g-1 after 200 cycles at 0.5 A g-1, alongside impressive rate capabilities of 936.4 mAh g-1 and 769.1 mAh g-1 at 4 A g-1 and 5 A g-1, respectively. Additionally, the AHP binder demonstrates superior compatibility with lithium iron phosphate (LiFePO4, LFP) cathodes. This work establishes inorganic binders as a practical and economical solution for high-performance μSi anodes, enhancing LIBs energy density and lifespan.