Pulsed Laser Deposition of Nanoporous Silicon Electrodes for Solid-State Lithium-Ion Cells

Owing to the huge theoretical specific capacity, nanostructured silicon is a promising anode material for all-solid-state lithium-ion batteries. However, the massive volume expansion associated with the formation of Li-rich alloys results in severe degradation and rapid failure. This study explores pulsed laser deposition (PLD) as a versatile technique for synthesizing nanostructured porous silicon thin films with tailored morphology and nanocrystallinity, intended for electrochemical testing in cells with Li₆PS₅Cl solid electrolyte. By systematically varying the deposition parameters, such as laser fluence, gas composition and pressure, substrate, and time, the transition from compact-amorphous to nanoporous-nanocrystalline silicon is achieved. Electrochemical testing reveals a strong correlation between nanoporosity and performance: the nanoporous film grown at 100 Pa of Ar + H₂ delivers a first-lithiation capacity of 3388 mAh g^-1 (94.7% of theoretical capacity), with stable cycling over 30 cycles, outperforming denser films. Post-mortem microscopy, Raman, and X-ray photoelectron spectroscopy analyses clarify lithiation-induced phase transitions and degradation pathways. Despite some still open challenges (such as low mass loading and poor initial Coulombic efficiency), this work demonstrates, for the first time, the rational application of PLD for silicon electrodes in solid-state lithium-ion cells, paving the way for further optimization and full-cell integration.