Study On Modification And Application Of Polypropylene Carbonate-based Solid Electrolyte

In all solid-state lithium batteries,the most critical component is the solid electrolyte that replaces the diaphragm and liquid electrolyte in traditional lithium-ion batteries.Therefore,the development of a new generation of high-performance solid electrolyte is of great significance to the advancement of all solid-state lithium battery technology.Commonly used lithium ion solid electrolytes are mainly divided into two categories:inorganic solids and organic polymers,which have their own specialties in function.Among them,polymer electrolytes,especially gel electrolytes,have very high electrical conductivity and good flexibility,can improve the interface problems between the inorganic solid electrolyte and the electrode,and can be easily prepared into various shapes,suitable for various This kind of complex equipment power source is a kind of solid electrolyte with good development momentum.According to the different substrates,all solid polymer electrolytes mainly include several types such as polyethylene oxide,polysiloxane and aliphatic polycarbonate.Among them,polypropylene carbonate(PPC),as a typical polymer electrolyte substrate without ether groups,has an amorphous structure and a flexible molecular chain that can rotate freely,and has a high dielectric constant group on the main chain.Clusters help to improve the ionic conductivity and electrochemical window of the solid polymer electrolyte,which has very important development value.In order to further improve the electrochemical performance of the poly(propylene carbonate)electrolyte,this article carried out a series of studies on the improvement of the performance of poly(propylene carbonate)electrolyte materials.Firstly,the PPC-based polymer electrolyte was doped and modified by doping with ionic liquid(VIm-TFSI),and the PPC electrolyte doped with ionic liquid(PPC-IL)was studied.The electrochemical performance.The experimental results show that after plasticization with ionic liquid,the prepared PPC-IL polymer electrolyte has an ionic conductivity of 8.2×10^-5 S cm^-1 at room temperature,and at a discharge rate of0.2C,LFP/PPC-The IL/Li battery still has a capacity retention rate of 66.2%after 200cycles,and its discharge capacity is as high as 77.1 m Ah g^-1.Subsequently,a PPC-Si O₂composite solid polymer electrolyte doped and modified with nano-silica was used,and the performance was compared with the traditional polyethylene oxide(PEO)-based electrolyte.The experimental results show that,compared with the PEO composite electrolyte system,the PPC-Si O₂ composite polymer electrolyte exhibits excellent electrochemical performance,and its room temperature lithium ion migration number can reach 0.66.At a discharge rate of 0.2C,the LFP/PPC-Si O₂/Li battery can still maintain 75.4%of the initial capacity after 200 cycles.Finally,the PPC-Si O₂ composite polymer electrolyte was coated on the ordinary Celgard-p diaphragm,and a composite polymer coating film was prepared and used in lithium-sulfur(Li-S)batteries.The experimental results show that(S/PAN)/M-Celgard-p/Li battery exhibits superior cycle performance and high temperature performance.The(S/PAN)/M-Celgard-p/Li battery can still release a capacity of 724.7 m Ah g^-1 after being cycled for 200 cycles at a current of 1.0 A g^-1.At 60?,the capacity retention rate after 200 cycles of cycling is 69.4%.The work of this paper shows.PPC-based polyelectrolytes have considerable application potential in the field of energy storage.