Laser Ablation for Managing Mechanical Stresses in High-Capacity Silicon Anodes for Lithium-Ion Batteries

Nano-silicon (<10 nm) particles with a pitch-derived carbon coating have been shown to enable stable cycling in low loading anodes. However, delamination and shredding quickly occurs for loadings of 3 mAh cm-2 and above. In this work, we explore laser ablation as a means of preventing mechanical failure in high loading (5 mAh cm-2) silicon anodes. Patterning is accomplished using a femtosecond laser to yield well-defined hexagonal prisms without damage to the current collector. Simulation work finds that patterning lowers the accumulation of stresses to successfully prevent failure that would normally occur. In practice, patterning is shown to enable prelithiation and stable cycling of high-loading electrodes. Prelithiated patterned electrodes are harvested and paired against NMC cathodes and go on to complete over 500 cycles at current densities corresponding to C/3. Differential capacity analysis and hybrid pulse power characterization show that reducing the prism size tends to slow the accumulation of overpotentials, impedance, and polarization. However, X-ray computed tomography reveals that the inscribed channels become congested upon lithiation affecting ion transport and limiting the utilizable capacity in the bulk electrode. This work contributes to the realization of practical high-loading silicon anodes that would otherwise be susceptible to mechanical failure.