Research On Novel All-Solid-State Battery Systems With High Safety

The fact of energy shortage is forcing and urging people to seek for renewable clean energy which can not only prevent the global-warming and air pollution issues caused by the heavy combustion of fossil fuels but also be circularly generated.In order to integrate the power coming from renewable energy into smarter and more powerful grid,energy storage and conversion problems should be considered.Lithium-ion battery(LIB)is one of the most popular energy storage systems in current commercial applications.Due to its long life-span,high energy density and rechargeable feature,LIBs are increasingly pursued for electronic portable devices and electrical vehicles.However,there is an emerging concern on the affordability of LIBs on account of the comparatively limited reserves and uneven distribution of lithium element.Therefore,it's urgent to shift research efforts to developing other energy storage system technologies.Secondary potassium-ion battery(PIB)has the prospect of becoming the substitute of secondary LIB due to its high abundance,low cost and high potential.However,similar to LIBs and sodium-ion batteries(SIBs),the safety concerns caused by high flammable organic-liquid electrolyte have hindered its further development.Moreover,the safety issues may be even more severe in PIBs on account of the higher chemical reactivity of potassium than that of sodium and lithium.Current researches about PIB mainly concentrate on the development of cathode and anode electrode materials while the application of solid-state electrolyte in PIBs and the safety problems are finitely studied.In this work,we are devoted to the application of solid polymer electrolyte(SPE)in PIBs so as to enhance the safety of PIBs.Firstly,we gave an introduction of the materials and classifications of solid-state electrolyte,as well as the development history of SPEs in various energy storage systems.Then,we studied the applicability of PPC-based and PEO-based SPEs in different PIB systems.The details are presented below.(1)We investigated the all-solid-state PIB which was based on PPC SPE and organic cathode.PPC-based SPE has the advantage of environmental friendliness and high ionic conductivity at room temperature while organic cathode provides a novel avenue to develop high-capacity energy storage systems and have been thoroughly studied in LIBs.Nevertheless,the solubility issue of small organic compound in organic-liquid electrolyte is quite severe and causes safety concerns and poor cyclicity.In order to solve the aforementioned issues,we designed an all-solid-state PIB built on 3,4,9,10-perylene-tetracarboxylicacid-dianhydride cathode(PTCDA)and SPE with nonwoven cellulose as the frame and PPC as the ion transit material.The solid-state PIB exhibits better cycling performance and higher safety at ambient than that of the liquid battery using the same cathode electrode.(2)We did research on all-solid-state PIB with PEO-based SPE and sulfide electrode.Firstly,we successfully synthesized nano Ni2S3 array on Nickel foam by hydrothermal method and investigated the morphology evolution of nanostructure as hydrothermal time changes.Then the uniform mixture of PEO and bis(fluorosulfonyl)imide potassium(KFSI)was heated for 12 hours under 70? and was pressed into SPE thin film.Finally,we assembled the all-solid-state PIB based on PEO SPE and Ni2S3 electrode.The all-solid-state PIB with PEO-based SPE can not only effectively resolve safety problems,but also prevent the capacity fade resulted from the high solubleness of polysulfide in organic-liquid electrolyte.The Ni2S3 electrode in PIB exhibits an initial discharge capacity of 312 mAh/g with current density of 25 mA/g at 55? and meantime excellent cycling performance and high coulombic efficiency.