A facile, low-cost synthesis of high-performance silicon-based composite anodes with high tap density for lithium-ion batteries

Abstract

Micro-sized carbon-coated Si-based composites have been developed by a simple mechanochemical reaction between SiO, Ni, and Al, followed by an additional milling process with graphite. The resultant carbon-coated Si-based composite exhibits a reversible capacity of over 580 mA h g⁻¹ after 200 cycles with a considerably higher tap density of ∼1.34 g cm⁻³ compared to nanosized Si (∼0.16 g cm⁻³). The improvement in the electrochemical performance is achieved due to both highly conductive NiSi₂ nanoinclusions and amorphous Al₂O₃ buffer matrix in the composite. Upon cycling, the multifunctional NiSi₂ phase not only provides enhanced electronic conductivity but also suppresses the formation of crystalline Li₁₅Si₄ that causes an inhomogeneous volume change. Simultaneously, amorphous Al₂O₃ plays a crucial role in maintaining particle connectivity by impeding the agglomeration of active Si nanocrystallites. The combination of these advantages with a low-cost, scalable, and environmentally benign synthetic process make the Si-based composite a promising alternative anode for high performance Li-ion batteries.