Carbon coating optimization on porous silicon as high-performance anode material via fluidized bed chemical vapor deposition

Abstract

The carbon layer coating is a promising solution to volume expansion and low electron conductivity in silicon-based anodes during lithiation. While numerous methods exist to generate these carbon coatings, Fluidized Bed Chemical Vapor Deposition (FBCVD) has proven superior due to its capacity for producing remarkably uniform and consistent carbon layers, primarily as a result of efficient mass and heat transfer characteristics. However, its application in the context of lithium-ion battery anodes has been sparsely explored and has been principally limited to silicon oxide as the base material. In this paper, porous silicon (PSi) obtained through acid etching of AlSi alloy with an average particle size of 300 mesh was taken as raw materials, and a fluidized bed reactor was employed to realize a uniform and tightly packed carbon layer. Relatively speaking, the PSi@C30 in this work offers a simpler process and promising electrochemical performance, opening a new door for the preparation of high-performance silicon-carbon anodes by FBCVD. Besides, PSi and high-quality carbon layers with structural advantages enabled the authors to obtain high-performance silicon-carbon anode materials. The resulting PSi@C30 composite demonstrated excellent initial coulomb efficiency (88.8 %) and cycling stability (with 83 % capacity retention after 100 cycles at 0.5 A g-1 and a reversible capacity of 1408 mAh g-1). Such a cost-effective and user-friendly technique facilitates the application of FBCVD in silicon-based anode materials for Li-ion batteries, thus accelerating the industrialization of silicon-carbon anodes for high-performance Li-ion batteries in the future.