The Fabrication of in Situ Polymerization of 1,3-Dioxlane/Poly(vinyl alcohol)/Polyethylenimine Quasi-Solid Polymer Electrolyte for a Lithium Metal Battery Operated at Low Temperatures

The development of a high-performanceelectrolyte that can workat low temperatures is critical for expanding the application of lithiummetal batteries. However, most of the present electrolytes sufferfrom low ionic conductivity and poor interface contact at low temperatures.Herein, an & SIM;21 & mu;m-thick quasi-solid polymer electrolyteis prepared by in situ polymerization of 1,3-dioxlane (PDOL) withinthe poly(vinyl alcohol)/polyethylenimine (PVA/PEI) nanofiber skeletonthat contains -NH- groups. The generated hydrogen bondinteractions between PDOL and PVA/PEI nanofiber, together with theinherently strong mechanical strength of the nanofiber, confer quasi-solidpolymer electrolyte (QSE@PVA/PEI) the tensile strength of 12.1 MPa.Meanwhile, the interactions also interfere with the chain arrangementof PDOL and efficiently enhance the chain mobility, giving QSE@PVA/PEIa remarkable ionic conductivity of 3.29 x 10(-5) S cm(-1) and a high Li+ transferencenumber of 0.437 at -60 & DEG;C. As a result, the Li/QSE@PVA/PEI/Licell can operate over 1500 h without obvious polarization at 0.2 mAcm(-2) and -20 & DEG;C. Moreover, the NCM523/QSE@PVA/PEI/Licell can stably cycle at -20 & DEG;C, delivering a high dischargecapacity of 106.7 mAh g(-1) over 600 cycles at 0.2C, which outperforms most reported electrolytes. Even at -40 & DEG;C, a modest discharge capacity of 75.2 mAh g(-1) is obtained at 0.2 C.

Automated summary

The development of a high-performance electrolyte that can work at low temperatures is crucial for expanding the application of lithium metal batteries. This study presents the preparation of a 21 μm-thick quasi-solid polymer electrolyte with excellent mechanical strength and high ionic conductivity by in situ polymerization within a nanofiber skeleton. The resulting polymer electrolyte demonstrates long-term stability and high discharge capacity at low temperatures, outperforming most reported electrolytes.