A Mutifunctional Supercapacitor Based On Self-healing Gel Electrolyte

Intelligent wearable electronics is the trend of the 21 st century.Whether Google glasses or apple watches,flexible electrochemical energy storage devices are the "beating heart" of the equipment.Flexible wearable electronics,however,is faced with many physical damage,such as acupuncture,bending,stretching,shearing and other physical effects could lead to a functional disorder of energy storage devices and even cause extreme security problems.Furthermore,discarded electronic waste is becoming more and more filled with our living environment.Therefore,design a kind of regeneratable and self-healing electrochemical energy storage device is the priority,which can notonly heal itself when physically damaged but alsobe reused after easy regeneration.Self-healing gel electrolyte is one of the cores of the intelligent electrochemical energy storage devices.Here,we utilized free radical reaction of the hydroxypropyl acrylate with 1-vinyl imidazole to get the P(VI-co-HPA)/NaNO3 self-healing gel electrolyte which showed excellent ionic conductivity,frost resistance and self-healbility.When the concentration of NaNO3 is 3 M,the ionic conductivity of the gel electrolyte can be reached 57 mS/cm and 17 mS/cm at room temperature and-15 oC respectively.Besides,its mechanical strength can recover 90% in just 5 min and 3h at the temperature aforementioned.When assemblied supercapacitors with active carbon,the capacitor showed excellent electrochemical performance and self-healing characteristic at both room and subzero temperature.It can maitain the specific capacity of 90 F/g and 30 F/g for 20000 and 8000 cycles at 25 oC and-15 oC respectively.After 9 times of cut/heal process,The CV,EIS and GCD curves of the capacitor are almost the same as the initial and the capacity retention is close to 100%.Besides,the capacitor can still keep a good cycle stability after self-healed.The capacitance retention can be reached more than 90% after 20000 and 5000 cycles at 25 oC and-15 oC respectively.Furthermore,the capacitor also showed a good performance of regeneration.During at least 5 times of drying/wetting test,the ionic conductivity of the gel electrolyte keeps around 50 mS/cm.After 5 times of regeneration,the capacity retention of the capacitor is 57% and it could cycle 5000 times without capacity attenuation.More interstingly,the capacitor also retained the original self-healing ability after regeneration.While healed at 25 oC and-15 oC,the capacity retention of the regenerated capacitor is close to 100% and 60% respectively.Finally,we used H2SO4 to fabricate P(VI-co-HPA)/H2SO4 gel electrolyte after which a layer of polyanilinein was situ growthed on the surface to make the integrated supercapacitor.Its area specific capacity increases with the increase of concentration of aniline monomers.When the concentration of aniline monomer is 0.3 mol/L,the coulomb efficiency of the capacitor is close to 100%.It can cycle 10000 times under the current density of 2 mA/cm2 without capacity attenuation and the area specific capacitance is around 405 mF/cm2;Besides,when the concentration of aniline monomer increased to 0.5 mol/L,the area specific capacitance can be reached up to 839 mF/cm2 while its capacity retention is about 68% after 3000 cycles.Furthermore,the integrated supercapacitor showed excellent self-healability.After 10 times of cut/heal,The CV,EIS and GCD curves of the capacitor comprised of 0.3 mol/L aniline are almost the same as the initial and the capacity retention is close to 91%.