Synthesis of boron-doped Si particles by ball milling and application in Li-ion batteries

Boron-doped Si particles were prepared by high-energy ball-milling of pure B and Si in various proportions (0, 1020, 1021, 1022 and 1023 atoms B per mole Si). Despite the fact that only a fraction of the added B atoms were incorporated into the Si lattice, a significant decrease of the Si electrical resistivity was observed, leading to a minimum electrical resistivity of 0.13 Ω cm for the sample milled with 1021 atoms B per mole Si compared to 190 Ω cm for the boron-free sample. Electrochemical investigations focused on these two samples showed that the B-doping of Si does not improve significantly the performance of the composite Si-based electrode for Li-ion batteries in terms of cycle life, coulombic efficiency and high-rate chargeability. Through an analysis of anodic polarization curves, it was also shown that the delithiation reaction is mainly controlled by the Li-diffusion kinetics from a rate of ∼4C on both electrodes. Lastly, it was shown that the use of a resonant acoustic mixer for the mixing of the (Si + carbon black + carboxymethyl cellulose) components increases the cycle life of the composite electrode.