Defects-Abundant Ga₂ O₃ Nanobricks Enabled Multifunctional Solid Polymer Electrolyte for Superior Lithium-Metal...

Polyethylene oxide (PEO)-based polymer electrolytes with good flexibility and viscoelasticity, low interfacial resistance, and fabricating cost have caught worldwide attention, but their practical application is still hampered by the instability at high voltages and the low ionic conductivity (10^-8 to 10^-6  S cm^-1 ). Herein, we rationally designed defects-abundant Ga₂ O₃ nanobricks as multifunctional fillers and constructed a PEO-based organic-inorganic electrolyte for lithium metal batteries. Due to the abundant O-defects feature of Ga₂ O₃ filler, this PEO-based composite electrolyte not only broadens electrochemical stability window (over 5.3 V versus Li/Li⁺ ) but also in situ forms a Li-Ga alloy and solid electrolyte interphase (SEI) film during the cycling process causing a rapid diffusion of Li⁺ ions. The as-prepared electrolyte has good interface compatibility with Li metal (without short-circuiting over 500 h at 0.2 mA cm^-2 ) and possesses superior high ionic conductivity. The assembled all-solid-state LiFePO₄ //Li cells attained an excellent cycling performance of 146 mAh g^-1 over 100 cycles at 0.5 C. The XPS analysis reveals that Ga₂ O₃ nanobricks can form in situ a Li-Ga alloy layer at the polymer/anode interface. This work shed a light on designing high ionic conductivity lithium alloys in the composite electrolyte, which can improve the electrochemical properties of PEO-based polymer electrolytes.