Electrophoretically deposited carbon nanotube anchor layer to improve areal capacity of Si-O-C composite anode for lithium secondary batteries

In this study, we report the preparation of carbon nanotubes (CNTs) anchor layer on a Cu substrate (CNTs/Cu) by using electrophoretic deposition technique. The CNTs anchor layer increases adhesion strength between Si-O-C composites and Cu substrate, as a result, it is possible to improve deposited Si amounts and areal capacity. The electrodeposited Si-O-C composites on CNTs/Cu (Si-O-C/CNTs/Cu) show homogenously coated surface morphology without cracks even large passing charge for electrodeposition of 15 C cm⁻², resulting in 0.21 mg cm⁻² of deposited Si amounts. On the other hand, Si-O-C composites deposited on as-received Cu substrate (Si-O-C/Cu) begin to peel off from substrate at 8 C cm⁻² of passing charge, resulting in 0.13 mg cm⁻² of deposited Si amounts, and decrease down to 0.10 mg cm⁻² at 15 C cm⁻² of passing charge. As a results, the improved Si amounts deposited on CNTs/Cu substrate achieve higher areal capacity, delivering 0.24 mA h cm⁻², which attains increase in 84.6% in comparison to Si-O-C/Cu, which has areal capacity of 0.13 mA g cm⁻² at 8 C cm⁻² of passing charge. Moreover, the Si-O-C/CNTs/Cu shows improved anode performances including discharge capacity and C-rate performance of the Si-O-C composites than Si-O-C/Cu without CNTs anchor layer.