Design And Preparation Of The Strong,tough And Highly Conductive Hydrogel Electrolyte For Zinc Ion Batteries

In recent years,the demand for wearable and portable electronic products has promoted the rapid development of flexible energy storage devices.Specially,zinc ion batteries have been widely concerned due to the abundant resources,high safety,environmental friendliness and low cost.The liquid electrolyte is unsuitable for flexible energy storage due to potential leakage risk,while hydrogel electrolytes do not have above problems.Therefore,designing the hydrogel electrolyte with excellent comprehensive properties is of great significance to promote the development and application of flexible zinc ion batteries.Traditional hydrogels generally possess poor mechanical properties,resulting in producing the dendrite puncture and unsatisfactory durability.Additionally,the water contained in the hydrogel will gradually volatilize with the passage of time or the increase of the ambient temperature.It will also freeze in the low temperature environment,which is harmful to the battery performance.These disadvantages limit its application in some special occasions.In order to solve the above problems,this paper prepared the hydrogel electrolytes with compression performance and high ionic conductivity over wide temperature,respectively.The results are as follows:（1）A highly compressible hydrogel electrolyte was fabricated by introducing soy protein isolate（SPI）nanoparticles into a covalently cross-linked polyacrylamide（PAAm）polymer network.SPI nanoparticles were concentrated on PAAm chains through weak electrostatic interaction which could dissipate energy efficiently,endowing the SPI/PAAm hydrogel electrolytes with excellent reversible compressibility.Thus,the Zn-Mn O₂battery based on the compressible hydrogel electrolyte exhibited good specific capacity(299.3 m Ah g^-1)and ideal capacity retention rate（78.2%）after 500 charge/discharge cycles.Surprisingly,the flexible Zn-Mn O₂battery could maintain stable power output under 96%compressive strain,even could light the bulb under severe mechanical stimulis such as bending and hammering.（2）High concentration of Zn（TFSI）₂and Li TFSI mixed solution was introduced into carrageenan/poly（sulfobetaine methacrylate-co-acrylamide）daul-network hydrogel by solvent replacement method to obtain prominent hydrogel electrolyte(K_3.6S₁A₂₀/Zn（TFSI）₂+Li TFSI)with all-climate property,which showed remarkable performance in-40～80℃.Significantly,the assembled Zn-Mn O₂battery could work normally at-30～60℃and maintain stable energy output under the conditions of compression and bending,due to decent interface adhesion of the hydrogel electrolyte.In conclusion,this paper successfully prepared high performance hydrogel electrolytes with compressibility and weatherability,which enhanced the properties of hydrogel electrolytes and provided a new idea for the design of novel hydrogel electrolytes and the construction of flexible zinc ion batteries.