Ultrashort pulsed laser texturing of current collector for Si/C Li-ion anodes: Characterization of electrochemical performance and evolution of interface morphology

Ultrashort pulsed laser texturing of copper current collectors (CCs) for next-generation Li-ion batteries with composite silicon-graphite anodes is conducted to enhance contact area and improve stress distribution at the interface between CCs and electrode active material. Linearly polarized IR femtosecond laser pulses are used to create sub-micrometric ripples (Cu_L1) and micro-grooves (Cu_L2) via self-modeling phenomena, while direct laser interference patterning (DLIP) with UV femtosecond laser pulses is employed to form micrometric cones (Cu_L3). Pristine (Cu_P) and laser-textured CCs are assembled using half-cell configuration for electrochemical testing, revealing improvements in cyclability and capacity retention with laser-textured CCs. During formation cycles at 0.1C, electrodes with Cu_P CCs exhibit an average specific capacity of 641.8 mAh g(-1), whereas those with Cu_L1, Cu_L2, and Cu_L3 CCs achieve 705.3 mAh g(-1), 673.0 mAh g(-1), and 734.9 mAh g(-1), respectively. After 100 cycles, Cu_P electrodes retain 80 % capacity, while laser-textured electrodes show retention of 86.9 %, 83.0 %, and 84.6 %, respectively. AFM analysis of laser-textured CCs before cell assembly indicates a 9-16 % increase in the developed interfacial area ratio (Sdr), with material removal due to laser texturing, <9 %. SEM section analysis before and after electrochemical testing reveals changes in interface morphology, with plastic deformation of CCs due to volumetric changes during charge/discharge cycling. The results suggest that laser texturing helps control plastic deformation at the interface, with SEM analysis providing direct evidence of changes in deformation and stress distribution.