ZnO Quantum Dots as PEO-Based Solid Electrolytes Fillers for Lithium Metal Batteries.

PEO-based solid polymer electrolyte (PEO SPE) is regarded as one of the most promising solid electrolytes due to its exceptional flexibility, cost-effectiveness, and ease of integration. However, its commercialization is hindered by inadequate ionic conductivity and unstable interface. By incorporating proper ZnO quantum-dots (QDs) fillers with enhanced surface activity, the ion transport inner the PEO-based electrolyte can be improved along with enhanced REDOX kinetics at the Li/PEO interface. The ionic conductivity reaches 5.97×10^-4 S cm^-1 at 60 °C. Moreover, ZnO QDs exhibit a quantum size effect and possess lithiophilic characteristics that promote uniform nucleation and redeposition of Li⁺ while forming a stable Li-Zn alloy. This inhibits lithium dendrite formation and enhances the stability of Li anode. Li//Li cell with 3 % ZnO QDs works steadily for more than 2100 h at 60 °C with 0.1 mA cm^-2. The assembled Li//LiFePO₄ cell provides a reversible capacity of 134.91 mAh g^-1 after200 cycles at 0.1 C.