Hybrid lithium salts regulated solid polymer electrolyte for high-temperature lithium metal battery

Herein, a blending solid polymer electrolyte that composed of polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF) was prepared by a simple solution-casting method, and the effect of different lithium salts on electrochemical performance at high operating temperature was studied. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) tests were performed to reveal the physical properties of obtained electrolytes, and electrochemical measurements demonstrate that a mixture of different Li salts with appropriate ratio in PEO/PVDF (1:1) shows a better property at 60 ​°C. The assembled LiFePO4||Li solid cells can reach a specific capacity of 160 mAh g−1 with an ionic conductivity of 9.12 ​× ​10−5 ​S ​cm−1. Contributed to the adopt of dual-salts, a high tLi+ value of 0.66 was obtained. It can be seen that the addition of rigid polymer into a soft matrix can effectively enhance the mechanical strength of solid polymer electrolytes to resist the dimensional loss at high temperature, and the mixture Li salts can improve the electrochemical properties. As a result, this work can provide a practical solution for assembly high safety solid Li metal battery for high temperature.