Mechanism analysis of precursor structure regulating silicon deposition and volume stability of SiC anode

Silicon (Si) has become a promising anode material due to its ultra-high theoretical specific capacity, but it is accompanied by severe volume changes during the deintercalation of lithium, which seriously restricts its practical application. At present, silicon nanoparticles are deposited into the pores of porous carbon by chemical vapor deposition (CVD) method, which can prepare vapor-deposited silicon‑carbon materials with high specific capacity and low volume expansion, showing broad application prospects. However, the structural differences of porous carbons with different precursors will significantly affect the deposition behavior of silicon. Based on this, biomass-based silicon carbon (B-PCSC), petroleum coke-based silicon carbon (PC-PCSC) and resin-based silicon carbon (R-PCSC) were prepared by CVD method using biomass-based porous carbon (B-PC), petroleum coke-based porous carbon (PC-PC) and resin-based porous carbon (R-PC) as substrates. The pore size of R-PC is the highest in 1.5–3 nm, which is more conducive to the deposition of silane. The proportion of ultramicropores (<0.7 nm) in B-PC is the highest, which is not conducive to the deposition of silane. The single particle crushing force of R-PCSC is 39.5% and 8.1% higher than that of B-PCSC and PC-PCSC, respectively. Expansion tests on pouch battery revealed that, after 100 cycles at 0.5C rate, the charge specific capacity of R-PCSC is 1135.59 mAh g −1 , which is better than that of B-PCSC and PC-PCSC. After 100 cycles at 1C, the irreversible expansion thickness of R-PCSC is 5.9 μm and 2.3 μm lower than that of B-PCSC and PC-PCSC, respectively.