| With the rapid development of portable electronic devices and electric vehicles,exploring high-performance energy storage devices with high energy density and excellent safety has become the primary task.As one of the important energy storage devices for solving the scarcity of non-renewable fossil fuel resources,supercapacitors?SCs?have attracted extensive attention due to their outstanding power density,fast charge-discharge efficiency and long cycle life.However,the problems of electrolyte leakage,high quality,inflexibility,and poor safety in traditional liquid SCs limits their application in next-generation electronic devices.All solid-state supercapacitors?SSCs?using polymer gels as electrolytes have solved the shortcomings of traditional SCs and can greatly satisfy the demand of electronic products for lightweight,flexible and high-security.The development of gel polymer electrolytes?GPEs?is the key to the development of SSCs.Most of the GPEs that have been reported are non-renewable polymers,and the flammability of these polymers still possess a safety hazard for electronic devices.Therefore,it is very practical to develop a renewable self flame-retardant GPE.Marine natural polymer?alginate,carrageenan?is a natural,renewable and environmentally friendly macromolecule.It has been widely used in food additives,cosmetics raw materials and medical materials due to its good biocompatibility and biodegradability.The gel properties of marine natural polymer?alginate,carrageenan?make it possible to apply to GPEs for SSCs.In addition,alginate and carrageenan have an amorphous structure,which can improve the ionic conductivity of GPEs.Most importantly,alginate and carrageenan are inherently self-flammable and can fundamentally prevent spontaneous combustion of electronic devices.Therefore,GPEs prepared from marine natural polymer?alginate,carrageenan?which as a polymer matrix are of great potential value.In this paper,we using marine natural polymer?alginate,carrageenan?and their blends as polymer matrix to prepare three kinds of GPEs by simple solution casting method,and characterizing their physical and electrochemical properties.?1?Lithium alginate?Li-Alg?was used as the polymer matrix and lithium acetate?LiOAc?as the electrolyte salt.The flame retardant GPE?Li-Alg/LiOAc-2M FRGPE?with high ionic conductivity was successfully prepared by solution casting and coating.The obtained Li-Alg/LiOAc-2M FRGPE has an ultrahigh limit oxygen index?LOI?of 35 and an excellent ionic conductivity of 32.6 mS cm-1.The Li-Alg/LiOAc-2M FRGPE membrane can be stretched 1.2 times at a breaking strength of 0.85 MPa.When Li-Alg/LiOAc-2M FRGPE was applied to activated carbon-based SSC,it exhibits high specific capacitance(185.7 mF cm-2 at a current density of 5 mA cm-2).The soft packages SSC containing Li-Alg/LiOAc FRGPE has no dimensional deformation when used at high temperatures.?2?A blend of polyvinyl alcohol?PVA?and carrageenan?Car?as the polymer matrix?PC?and LiOAc as the electrolyte salt.The flame retardant GPE?PC30 FRGPE?was successfully prepared by solution casting and coating.The resulting PC30 FRGPE has a LOI of 30 and an excellent ionic conductivity of 34.13 mS cm-1.The PC30 FRGPE membrane can be stretched 1.2 times at a breaking strength of 0.4 MPa.The PC30 FRGPE-based SSC has a specific capacitance of 222 mF cm-2 at a current density of 5 mA cm-2.The PC30 FRGPE-based SSC can still illuminate the LED in a bent state.?3?Li-Alg and Car blend?A/C?were used as the polymer matrix and LiOAc as the electrolyte salt.The flame retardant GPE?A/C-50 FRGPE?was successfully prepared by solution casting and coating.The resulting A/C-50 FRGPE has a high ionic conductivity of45.7 mS cm-1.The addition of Li-Alg increases the mechanical strength of A/C-50 FRGPE,A/C-50 FRGPE membrane can be stretched 1.7 times at a breaking strength of 180 kPa.The A/C-50 FRGPE-based SSC has a specific capacitance of 243.96 mF cm-2 at a current density of 5 mA cm-2. |
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