A homogenous solid polymer electrolyte prepared by facile spray drying method is used for room-temperature solid lithium metal batteries

The aggregation of inorganic particles with high mass ratio will form a heterogeneous electric field in the solid polymer electrolytes (SPEs), which is difficult to be compatible with lithium anode, leading to inadequate ionic conductivity. Herein, a facile spray drying method is adopted to increase the mass ratio of inorganic particles and solve the aggregation problems of fillers simultaneously. The polyvinylidene fluoride (PVDF) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) covers the surface of each Li6.4La3Zr1.4Ta0.6O12 (LLZTO) granules during the nebulization process, then forming flat solid electrolytes via layer-by-layer deposition. Characterized by the atomic force microscope, the obtained solid electrolytes achieve a homogenous dispersion of Young's modulus and surface electric field. As a result, the as-prepared SPEs present high tensile strength of 7.1 MPa, high ionic conductivity of 1.86 × 10−4 S·cm−1 at room temperature, and wide electrochemical window up to 5.0 V, demonstrating increased mechanical strength and uniform lithium-ion migration channels for SPEs. Thanks to the as-prepared SPEs, the lithium-symmetrical cells show a highly stable Li plating/stripping cycling for over 1,000 h at 0.1 mA·cm−2. The corresponding Li/LCoO2 batteries also present good rate capability and excellent cyclic performance with capacity retention of 80% after 100 cycles at room temperature.