Exceptional fabrication of dead-weight-free silicon and graphitic heterostructures anodes for the next advancement of Li-ion batteries

Abstract

Silicon (Si)-graphite and graphite (without Si) anodes for Li-ion batteries are developed at ambient conditions through the direct irradiation of CO2 laser, resulting in avoiding the use of binders, conductive carbon additives, and organic and water-based solvents. Furfuryl alcohol (FA) is mixed with Si-graphite and graphite, prepared viscous slurry through the heating, cast on the copper foil, and dried. Irradiation of CO2 laser at the electrode of Si-graphite-FA generates in-situ hetero-structures of Si particles, SiC/Si-SiC nanowires made of spontaneously carbon-coated/oxidized nano-layer (∼ 3nm), and graphitic carbon containing few layers of graphene. All the laser-fabricated electrode material is electrochemically active (∼ 0% dead weight) in the Si-graphite and graphite anodes since the FA converts to the graphitic carbon containing few layers of graphene; thus, the fabrication method could benefit the next industrial development. The discharge capacity of the Si-graphite electrode with total material loading is recorded at 502.2 mAh/g (∼ 1.9 mAh cm−2) and capacity retention of ∼ 80 % over the 50 cycles vs. Li/Li+. Also, it shows good discharge capacity when fabricated with NMC622 in full-cell format. Therefore, this performance is highly stable without any binder and conductive carbon, especially for Si-based battery, which fails rapidly due to substantial volume changes (∼ 300 %). Moreover, the performance is highly stable for graphite anode with a discharge capacity retention of 91 % over the 160 cycles as considered 100 % (∼ 345 mAh/g) after the formation cycle.