Construction Of Multi-level Structured PAM-based Gel Electrolyte And Its Application In Flexible Zinc Ion Capacitor

The emergence of flexible and wearable electronic devices has caused a lot of researches on stable,reliable,low-cost and wearable energy storage devices with excellent electrochemical performance.Flexible wearable zinc ion capacitors are expected to meet these needs.As one of the key materials for energy storage devices,hydrogel electrolyte is critical to realize flexible wearable zinc ion capacitor,so it is necessary to develop hydrogel electrolyte with excellent performance.In this paper,the hydrogel electrolyte based on polyacrylamide was studied and assembled into quasi-solid flexible zinc ion capacitor,and the basic electrochemical performance of the device was explored and studied.Moreover,the properties and mechanism of zinc dendrites inhibition with hydrogel electrolytes and the performance of zinc ion capacitors with hydrogel electrolytes under extreme conditions were also explored.The main research content is as follows:（1）A scalable,thin and hierarchical PAN/PAM based gel electrolyte with high electrochemical performance was prepared and applied to flexible zinc ion capacitors to obtain an extremely safe and flexible quasi solid state ZICs.The prepared quasi solid ZICs showed a high energy density of 106.5 Wh kg^-1,a high power density of1000 W kg^-1,an excellent specific capacity 106.0 m Ah g^-1,and a high capacity retention up to 100%15000 cycles.Moreover,the gel electrolyte was able to induce uniform deposition of zinc ions and was able to cycle for 2200 hours at a current density of 0.2 m A cm^-2.Particularly,the quasi solid ZICs exhibited excellent flexibility and good safety performance in various harsh situations,such as bending,hammering,piercing,cutting,soaking in water and fire-resistance performance.（2）A kind of PAM/Trehalose hierarchical gel electrolyte with covalent hydrogen bond interaction was fabricated.The hydrogel electrolyte shows a good self-healing ability due to the strong hydrogen bond network between trehalose rich hydroxyl groups and polar groups in PAM chain segment.The strong hydrogen bond network formed by trehalose not only improves the mechanical properties of the hydrogel electrolyte,but also improves the voltage window of the hydrogel electrolyte（0-2.1V）.In addition,the hydrogel electrolyte can induce a uniform deposition of Zn²⁺due to the hydroxy effect of trehalose and the polar group of PAM,thus inhibiting the growth of zinc dendrites.The Zinc-ion capacitor with the prepared electrolyte can cycle for 1900 hours at the current density of 0.5 m A cm^-2.Moreover,Zinc-ion capacitors with this gel electrolyte have showed good bending properties and potential practical applications.Most importantly,this energy storage device is able to be operated under many extreme conditions while maintaining excellent capacity retention.