Modulating current density engineers the microstructure of Ni/PET/Ni composite foils to boost solid state battery performance

Solid-state batteries (SSBs) face critical challenges from the corrosion and mechanical degradation of conventional copper current collectors. Nickel emerges as a promising alternative due to its superior anodic stability, yet its microstructure-property-performance relationship in composite collectors remains underexplored. Herein, we fabricate flexible Ni/PET/Ni composite foils by precisely modulating electroplating current density to engineer the nickel microstructure. The optimized foil prepared at 1 A/dm 2 (CNF-1) exhibits a refined surface morphology (1.2 µm), low surface roughness (Ra = 0.218 µm), high tensile strength (372.33 MPa), and exceptional corrosion resistance (1.785×10 –6 A/cm 2 ). When employed as an anode current collector in silicon-carbon‖lithium half cells, CNF-1 delivers a high initial discharge capacity of 597.98 mAh/g at 0.1 C with superior cycling stability, outperforming conventional copper foil. This work establishes current density modulation as a viable strategy for designing durable, high-performance current collectors for advanced SSBs.