Synergistic Enhancement Effects of LLZO Fibers and Interfacial Modification for Polymer Solid Electrolyte on the Ambient-Temperature Electrochemical Performances of Solid-State Battery

The low ionic conductivity of solid electrolyte and the poor interfacial compatibility with lithium anode are often restrain the electrochemical performances of the solid-state battery at ambient temperature. Herein, we for the first time applied electrospun Li 7 La 3 Zr 2 O 12 (LLZO) fibers and graphite coating simultaneously on polymer solid electrolyte (SE). The composite SE shows uniform composite structure, possesses a high potential window exceeding 4.6V and a high ionic conductivity of 1.59 × 10 −4 S/cm at ambient temperature. The assembled LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622)/SE/Li solid-state battery shows enhanced ambient-temperature electrochemical performance with an initial discharge capacity of 162.6 mAh/g and a retention capacity of 106.1 mAh/g after 200 cycles at a current density of 0.3C. While at 1C, the solid battery were still charged/discharged for 200 cycles with a retention capacity of 100.3 mAh/g. The enhanced ambient-temperature electrochemical performance is attributed to the synergistic effects of LLZO fibers and graphite coating modification for the composite SE, fibrous fast ion-conductors provide continuous ion transport channels, and graphite modification on the electrolyte surface improves the interface contact with lithium anode and restrains lithium dendrites. This design method for composite polymer solid electrolyte is expected to be popular in solid-state battery with high ambient-temperature performance.