Electrodeposited copper foams as substrates for thin film silicon electrodes

Although a significant amount of effort has been put into investigating elemental silicon as a lithium-ion battery anode material, limited progress has occurred in translating these results to create a long lived electrode. Several electrode level solutions have been reported including utilizing Si nanowires, thin films, and nanoparticle assemblies, where the physical diffusion distances are kept very short. For thin film based electrodes, the benefits of the simplified structure of the electrode are countered by the low surface area and low silicon loadings. In this study we have utilized electrodeposition techniques to deposit silicon films on a porous copper substrate. This greatly increases the electrode surface area and loadings while maintaining the advantages of a thin film electrode. Using 3d-silicon electrodes without a binder or conductive matrix, stable capacities of ∼ 1000 mAh/g have been achieved. In general, electrodes with lower loadings of active silicon (< 1 mg/cm²) displayed better rate capability than electrodes with higher loadings (> 2.5 mg/cm²).