Fabrication Of Compressible Electrodes Based On Melamine Sponge And Their Supercapacitor Performance

As the application of light-weight wearable electronic devices more and more widely,it is necessary to develop energy storage devices that can provide stable power output while resisting various physical deformations.Deformable supercapacitors with high power density have attracted attention.There have been many reports of bendable,stretchable,and curlable supercapacitors.However,there are relatively few studies on compressible supercapacitors,although compressible characteristics are also important for wearable electronic devices.Moreover,developing compressible supercapacitors that can maintain good electrochemical performance under high compressive strain remains a challenge.Melamine sponge(MS)with a porous three-dimensional network is widely used as a compressible substrate due to its excellent durability,water absorption and compressibility.It can not only provide superior compressibility,but also provide sufficient load space for active materials.In this paper,two kinds of compressible electrodes for supercapacitors were prepared by using MS as the substrate and loading active materials on it by a simple and low-cost method.Polypyrrole(PPy)is a common conductive polymer material.It is very suitable for the preparation of deformable energy storage devices due to its inherent flexibility and considerable specific capacity.However,poor rate performance and cycle stability are obstacles that hinder the further application of PPy.In this paper,3D compressible r GOPPy-r GO-MS(G-PPy-G-MS)electrodes were prepared by alternately coating graphene(r GO)and PPy on the skeleton of MS.PPy is synthesized by in-situ chemical polymerization.The loading of PPy on the electrode regulates the electrochemical performance of the sample,which can be adjusted by the amount of pyrrole monomer.In this paper,combining r GO with PPy can not only ensure high capacitance,but also greatly improve the cycling stability and rate performance of the electrode.The inherent toughness and elasticity of MS and PPy allow the electrode structure to avoid collapse under high compressive strain.The obtained G-PPy-G-MS electrode has a high-quality specific capacitance of 464.10 F·g-1 and ideal cycle stability,and its capacity retention rate is 85.43% after 5000 cycles.It shows good recovery ability under the maximum compression of 80%,and the G-PPy-G-MS electrode can still be restored to its original state after one hundred repeated compression.In order to develop a compressible electrode with a simpler and easier preparation process and excellent electrochemical performance,this article turned to poly 3,4-ethylenedioxythiophene:Poly(sodium-p-styrenesulfonate)(PEDOT:PSS)with high conductivity and excellent stability.The PEDOT:PSS polymer was prepared by chemical oxidation.The factors influencing the electrochemical performance of the electrode during the preparation process were also explored.Finally,the PEDOT-MS electrode exhibited a conductivity of 1.67 S·cm-1,and the volumetric capacitance reached 945.55 m F·cm-3.When the current density increased from 0.5 m A·cm-2 to 10 m A·cm-2,the capacitance retention rate was 13.22%.After 4000 cycles,the capacitance is 86.6% of the initial capacitance.