Elastic and well-aligned ceramic LLZO nanofiber based electrolytes for solid-state lithium batteries

Ceramic Li7La3Zr2O12 is one of the most attractive electrolyte materials for solid-state batteries due to its high ionic conductivity and chemical/thermal stability, but the battery performance is always limited by the high electrolyte-electrode interfacial resistances. Here, we have fabricated elastic solid electrolytes by filling ionic-conductive polymers into well-aligned Li6.4La3Zr2Al0.2O12 (LLZO) nanofiber films. Such electrolytes can provide fast and continuous ionic-transportation channels and thus exhibit a high ionic conductivity of 1.16 × 10−4 S cm−1 at 30 °C. Moreover, the elastic surfaces of the electrolytes can well conform to electrodes without separations to adapt volume changes of the electrodes during the repeated cycles, enabling a stable Li plating/stripping cycling over 700 h. Fabricated solid-state NCA//Li cells exhibit ultra-low internal resistances of 87 Ω and deliver large discharge capacities with high Coulombic efficiencies that are comparable with the liquid type batteries. The reported approach allows low-cost fabrication of solid electrolytes that possess high ionic conductivity for solid state batteries.