Preparation of porous silicon composite anode material coated with open pore polymethyl acrylate and its electrochemical performance as a carbon source

Abstract

Silicon (Si) is considered an ideal candidate for the next generation of lithium-ion batteries owing to its high specific capacity, low lithiation/delithiation potential, and abundance. However, its extensive volume expansion engenders electrode structure deterioration and cycle life truncation, substantially hindering its practical utility. In this investigation, we fashioned porous silicon via the etching of micron-sized aluminium–silicon alloy, and subsequently, porous silicon@hard carbon (PSi@C) composites were meticulously crafted through a sequence involving high-temperature pyrolysis after methyl acrylate (MA) suspension polymerization coating and a Soxhlet extraction pore-forming procedure. Characterization through scanning electron microscopy (SEM) revealed the composite material's abundance of pores and the presence of a fish-scale-like carbon framework. This unique architecture adeptly mitigates the stresses stemming from silicon's volumetric expansion, thus rectifying the issues associated with silicon's poor electronic conductivity and carbon materials’ limited capacity. Simultaneously, it utilizes silicon's high specific capacity and carbon's extended cycle stability. Remarkably, after 300 cycles at 0.5 A g⁻¹, the PSi@C electrode exhibited a capacity retention rate as high as 74.4% (652 mA h g⁻¹). Even under a high current of 2 A g⁻¹, the rate test still revealed a reversible capacity of 465 mA h g⁻¹. These findings indicate exemplary long-cycle and rate performance characteristics, underscoring significant potential for research and application in lithium battery energy storage.