| Considering the safety of lithium metal batteries,the most promising development direction is to replace traditional flammable organic electrolytes with solid electrolytes?SE?to solve issues fundamentally.Current studies on SE mainly focus on how to improve its ionic conductivity and improve solid electrolyte/electrode contact surface.In view of the above problems,this paper aims to obtain SE membranes with high ionic conductivity,good compatibility with lithium metal anodes,and stable cycling performance in SSLiBs.We designed PAN-based composite electrolyte,PEO composite electrolyte enhanced by 3D PAN/Garnet and TP film with high lithium ion transference numbers,good interface compatibility based on PAN polymer.The physical properties and electrochemical performance of SE membranes were studied systematically.Their applications in SSLiBs showed excellent cycle performance and the specific research contents are as follows:?1?PAN/LLZO solid electrolyte with high ionic conductivity was successfully prepared via solution-casting technique.Cubic LLZO was sintered by solid-state method,and the effect of LLZO addition on the properties of polymer electrolyte membrane was investigated via simple solution-casting technique.It is found that LLZO ceramic filler could provide extra channel for Li+,improve ionic conductivity and reduce the crystallinity of polymer,speed up the chain movement of polymer.And the composite solid electrolyte had higher ionic conductivity and better safety than polymer electrolyte,which made it possible for the application of solid-state lithium metal battery.?2?3D PEO/LLZO composite electrolyte with good thermal stability,mechanical property and conductivity was successfully prepared by electrostatic spinning technology.Firstly,the polymer electrolyte membrane prepared had good film-forming performance,mechanical property and thermal stability.Compared with pure PEO electrolyte membrane,its ionic conductivity and electrochemical stability were improved.In order to further optimize the electrochemical performance of the polymer electrolyte,we directly immersed the preformed three-dimensional ceramic structure into the polymer solution to obtain the ideal 3D composite electrolyte structure.DSC and FTIR measurements showed that LLZO could reduce the crystallinity of the polymer,and play a fixed role with the polymer chain segment on the anion TFSI-to promote the dissociation of lithium salts,increase the ionic conductivity by an order of magnitude(8.89×10-4 S cm-1),and increase t from 0.454 to 0.55.The SSLiBs showed superior cyclic performance.?3?TPFPP-PAN polymer electrolyte with high lithium ion migration number was prepared.By controlling the amount of TPFPP,the performance of PAN-based SPEs was optimized.Exploring the effect of the addition of TPFPP on PAN-based polymer electrolytes.TPFPP had certain complexation with LiTFSO,and promoted the increase of lithium ion migration and ionic conductivity.Lithium deposition/stripping curves proved that the improved TP film had better compatibility with lithium and improved the electrolyte/negative electrode interface.When applied to Li/LFP solid-state batteries,the specific capacity could reach 140.9 mA h g-1 and the capacity retention rate could maintain 98.6%after 200 cycles at 0.2 C.After cycling at different rates,the current density was sharply reduced to 0.1 C and the specific capacity could still recover to 143 mA h g-11 and the coulombic efficiency was maintained at 99.8%.The main reason is that TP film has high ionic conductivity and good compatibility with lithium metal.The main reason is that TP film has high ionic conductivity and good compatibility with lithium metal,which indicates that TPFPP has a certain application potential in solid-state batteries. |
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