PEO-based Polymer Electrolyte And Its Application In All-solid-state Lithiμm Sulfur Battery

Lithiμm-sulfur batteries are considered to be one of the most promising secondary batteries in the near future because of high theoretical specific capacity and low cost of active materials.There are still some problems in the traditional lithiμm-sulfur batteries,such as the volμme change of sulfur,the shuttle effect of polysulfides,and the safety of electrolytes.Currently,an effective way to solve the above problems is to use solid electrolyte instead of liquid electrolyte.In this paper,PEO polymer electrolytes used as matrix were compounded with PVDF,metal-organic framework（MOF5）and MOF-based ion conductors,respectively,preparing varied type of composite solid electrolytes.characterization and electrochemical tests were carried out in this work:1.The MOF5 material was added to PEO as filler to prepare a composite electrolyte.The result show that the PEO-Li TFSI-2%MOF5 exhibit high ion conductivity,reaching 5.01×10^-4S cm^-1at 60℃.In addition,the electrolyte also exhibits a wide electrochemical window（4.8V）,high transfer nμmber of Li⁺（0.31）.Lithiμm-sulfur battery based on this composite electrolyte also presents excellent cycling stability,with a capacity of 750 m Ah g^-1after 50cycles at 60℃and 0.1 C.2.The composite solid electrolyte is prepared by compounding PVDF,MOF5-NH₂and PEO.Owing to the hydrogen bonding between PVDF,MOF5-NH₂and PEO,the electrochemical performance of the electrolyte is improved.The result show that the9PEO-PVDF-2%MOF5-NH₂composite electrolyte exhibit high ion conductivity,reaching8.29×10^-4S cm^-1at 60℃.In addition,the electrolyte also exhibits a wide electrochemical window（5.4 V）,high transfer nμmber of Li⁺（0.38）.Lithiμm-sulfur battery based on this electrolyte also presents excellent cycling stability,with a capacity of 800 m Ah g^-1after 50cycles at 60℃and 0.1 C.3.Based on the nano porous nature of MOF materials,the ionic liquid can be absorbed into the pores by capillary adsorption to obtain IL-incorporated MOF composite.The composite was compounded with PEO polymer electrolyte to prepare the PEO-LIM composited electrolyte.The result show that the composite electrolyte exhibits high ion conductivity(8.29×10^-4S cm^-1at 60℃),high transfer nμmber of Li⁺（0.34）.In addition,the composited electrolyte has a good mechanical property,and the assembled lithiμm symmetric battery based on the electrolyte can be cycled stably for 160 h.