The Research Of Novel Polyethylene Oxide Based Polymer Electrolytes For All-solid-state Lithium Battery

The traditional lithium battery was occasionally accompanied by electrolyte leakage,spontaneous combustion and other safety incidents.Therefore,the solid polymer electrolyte（SPE）has a good opportunity to be developed by its unique safety.In order to improve the conductivity of SPE at room temperature,and promote the further development of all-solid-state lithium battery with polymer electrolyte,we have designed and prepared two kinds of polymer electrolyte with good performance in this paper:firstly,we modified the PEO-based polymer electrolyte;secondly,we created a new type of polymer electrolyte material.Additionally,these solid polymer electrolytes have the advantages of low cost,high safety,good mechanical properties,and stable electrochemical performance,etc.The results are as follows:（1）The PEO-based electrolyte has been modified by introducing the three component sulfide Li₁₀GeP₂S₁₂（LGPS）and solid plasticizer（SN）,and the ratio of each group was systematically investigated.The PEO-LiTFSI-1%LGPS-10%SN polymer electrolyte presents a maximum conductivity of 9.10×10^-5 Scm^-1 at 25°C,and a 15-fold ion conductivity enhancement in PEO-LiTFSI.Meanwhile,it exhibits wide electrochemical window（0⁵.5 V）and excellent compatibility with metallic Li.The LiFePO₄/Li batteries exhibit a good cycling and rate performance under 40°C,whose maximum discharge specific capacity at 0.1 C and 0.5 C are 160.6 and 138.4mAhg^-1respectively,and the high capacity retention ratios can be retained.Finally,the reasons of activation process are systematically discussed.（2）A new class of polymer electrolytes with tunable network structure is successfully designed and prepared via a one-pot reaction.The trimethylolpropane triglycidyl ether（TMPEG）is cross-linked with poly（ethylene glycol）diamine（NPEG）to create well-defined solid network polymer electrolyte（SNPE）.The optimal electrolyte TMPEG-NPEG4K[2:1]-16:1 presents a maximum conductivity of 1.10×10^-44 Scm^-1under 30°C,and an18-fold ionic conductivity enhancement in that of PEO-based electrolyte.Furthermore,it also exhibits wide electrochemical window（0⁵.4 V）,excellent compatibility with metallic Li,and superior mechanical properties.The all-solid-statelithiumbatteriesLiFePO₄/Liareassembledwith TMPEG-NPEG4K[2:1]-16:1 electrolyte,and present good cycling and rate performance under 60°C.The initial discharge specific capacities of the batteries are161.7 mAhg^-1 at 0.2 C and 132.7 mAhg^-1 at 1 C,and the capacity retention ratio can be retained at 90.6%and 90.5%after 100 cycles.