Silicon/graphene based nanocomposite anode: large-scale production and stable high capacity for lithium ion batteries

A Si/graphene nanocomposite, with nano-Si particles tightly wrapped and connected by graphene nanosheets, was prepared on a large scale by using discharge-plasma-assisted milling (P-milling). The nanocomposite with 50 wt% Si demonstrated high capacity, good cycleability, and an excellent high-rate capability as a lithium storage anode, which delivered a discharge capacity of 866 mA h g(-1) and a coulombic efficiency above 99.0% after 200 cycles under a current density of 0.4 mA cm(-2). The capacity loss above 200 cycles was only similar to 0.07% per cycle for 0.02-2 V. The practical relevance of this anode was further confirmed by a full coin-type cell with a LiMn2O4 cathode, which could cycle with stable capacities at practical working voltages between 3.2 and 4.2 V. Moreover, micro-Si mixed with WC and graphite was also treated by P-milling to form a core-shell-shell Si-WC/graphene nanocomposite with better cycleablity. These superior electrochemical properties were attributed to the highly enhanced structural stability and conductivity of the nanocomposite electrodes due to the complete coating of the micro/nano-Si particles by graphene nanosheets. The present Si/graphene based nanocomposite may have good potential for large-scale applications because of the cost-effective and easy scalability of its synthesis by P-milling processes.