context: The charging-discharging and cycling curves were obtained from the hybrid electrolyte cells, as displayed in Fig. 6c and d. The cells were charged/discharged with a constant current density of 0.3 mA cm−2 for the first cycle, 0.5 mA cm−2 for the second to sixth cycles, 1 mA cm−2 for the seventh to eleventh cycles and 1.4 mA cm−2 for longer cycles. The charging/discharging voltage profiles in Fig. 6c and d show that the cell with the laser-treated LLZTO sample has a relatively small overpotential even at a high current density of 1.4 mA cm−2. This result is consistent with the impedance result in Fig. 6a and b, as evident from the reduction of Nyquist curves. For the polished (pristine) LLZTO cell, the cell voltage was found to be unstable in the charging curve of the 8th cycle, implying the formation of an internal short-circuit caused by the propagation of metallic Li. In contrast, notably, the cell with the laser-treated LLZTO sample showed a stable cycling performance without any short-circuit signals (voltage noise and/or sudden drop) at a constant current density of 1.4 mA cm−2. The improved cycling stability of the laser-treated cell was confirmed from the cycling curves shown in Fig. 6e for long-term operation under 1.4 mA cm−2. The cell showed an excellent coulombic efficiency of 88.9% for 1st cycle, 100% for 3rd cycle, 100% for 7th cycle, 99.96% for 11th cycle, 99.92% for 50th cycle, 99.92% for 100th cycle, and 99.92% for 160th cycle compared with the conventional LIBs and a remarkable capacity retention of 96.7% over the 160th cycle. The mechanism to enhance the electrochemical performance in the laser-treated cell might be complicated. The surface change of LLZTO after the laser treatment includes the formation of Li2O2 and amorphous garnet, the possible reduction of LiOH and Li2CO3, and the morphological deformation. Based on our electronic structure analysis of the laser-treated LLZTO sample and its reduced electronic conductivity (Fig. S5c†), it is highly possible that the main origin of the remarkable improvement in the cycling stability of the laser-treated cell is the formation of the stable amorphous layer with a wide bandgap, which can significantly suppress the Li dendrite formation.