Micro-gradient patterned NiO coating on copper current collector for anode-free Lithium metal battery

An energy-economic, rapid and integrative CO2 laser-based photo-thermal process is demonstrated for slurry-coated nickel oxide (NiO) coating on copper (Cu) foil for use as a current collector (CC) in anode-free Li metal battery (AFLMB) application. The laser irradiation in rapid scanning mode under ambient atmosphere transforms the dense NiO coating into a porous yet highly adherent microstructure integrated with the metal substrate. The film quality was optimized by varying the laser power and scan rate. For the optimum case, the lithium ion transport investigations indicated improved Li+ de-solvation and faster lithium transport which is demonstrated by its lower activation barrier (50.13 kJ/Mol) than that for bare Cu (60.53 kJ/Mol). Also, the uniform lateral diffusion of lithium onto the NiO-modified current collector (NMCC) surface resulted in significant rise in the exchange current density (1.592 mA cm-2) than that in case of bare Cu (0.716 mA cm-2). This helped prevent the dendrite formation, and enhancing the cyclic stability of the AFLMB up to 400 cycles at room temperature as well as up to 700 cycles at the elevated temperature of 40oC as compared to only 150 cycles for bare Cu. The laser treated NMCC offered efficient lithiation on its surface which is demonstrated by lower nucleation overpotential down to 12 mV as compared to 39 mV for bare Cu. The optimum case of laser functionalized NiO-modified Cu CC in full cell with LFP retained 24% higher capacity at 100th cycle than the uncoated Cu CC.