Electrochemical properties of carbon-coated Si/B composite anode for lithium ion batteries

Carbon-coated Si and Si/B composite powders prepared by hydrocarbon gas (argon + 10 mol% propylene) pyrolysis were investigated as the anodes for lithium-ion batteries. Carbon-coated silicon anode demonstrated the first discharge and charge capacity as 1568 mAh g−1 and 1242 mAh g−1, respectively, with good capacity retention for 10 cycles. The capacity fading rate of carbon-coated Si/B composite anode decreased as the amounts of boron increased. In addition, the cycle life of carbon-coated Si/B/graphite composite anode has been significantly improved by using sodium carboxymethyl cellulose (NaCMC) and styrene butadiene rubber (SBR)/NaCMC mixture binders compared to the poly(vinylidene fluoride, PVdF) binder. A reversible capacity of about 550 mAh g−1 has been achieved at 0.05 mAm g−1 rate and its capacity could be maintained up to 450 mAh g−1 at high rate of 0.2 mAm g−1 even after 30 cycles. The improvement of the cycling performance is attributed to the lower interfacial resistance due to good electric contact between silicon particles and copper substrate.