Pseudocapacitor Modified Carbon Sponge And Its Compressible Capacitor Performance Research

The demand of various portable and wearable devices has stimulated the rapid development of light-weight and flexible energy storage systems with enhanced electrochemical performance and good mechanical property.In particular,compressible supercapacitors have received great attentions as they can endure a large level of strain while maintaining a stable electrochemical performance.However,developing compressible supercapacitor with high capacitance and excellent compressibility still remais a great challenge.This thesis focous on preparation of compressible CS substrate and further improve its electrocapacitive performance by growing NiCo2S4.In Charpter Ⅲ,compressible carbon sponge(CS)was prepared by a simple one-step pyrolysis of commercially available melamine sponge(MS).The obtained CS can endure a compressive strain as high as 80%and show no obvious change in structure and conductivity under a constant strain of 60%after compress-release cycles of 100 times.When tested as a compressible electrode in three-electrode system,CS exhibited a stable capacitive performance(～73 F g-1)and long-cycling stability under different strains(ε= 0-80%),showing it is one of promising candidate in compressible supercapacitors.In order to boost the capacitive performance of CS,in chapter IV,the pseudocapacitive NCS was introduced onto CS through a facile one-step solvent thermal method.The introduction of NCS does not influence the compressible property of CS,but enhance the the CS conductivity.It is note that sheet-like NCS displays more exposed electro-active sites which are desirable for sufficient Faradaic redox reaction.The resultant CS-NCS delivered a high specific capacitance of 1093 F g-1(0.5 A g-1),and retained 91%of its initial capacitance at 20 A g-1.Similarly,tested as a compressible electrode,the CS-NCS delivered a gravimetric capacitance of 369 F g-1 and volumetric capacitance of 20.9 F cm-3(ε= 60%),which are 5 times and 18 times higher than the pure CS,respectively.These results showed great potential of CS-NCS composite as a compressible cathode with highly capacitive performance.In charpter V,we prepared the pseudocapacitive Fe2O3 on CS to develop a compressible negative supercapacitor electrode.Pseudocapacitive Fe2O3 with nanorods and nanosheets were successfully deposited on the CS through hydrothermal method and electrodeposition method,respectively.We preliminarily studied the influence of crystal phase,morphology and mass loading mass of Fe2O3 on their capacitive performance.We found that γ-Fe2O3 nanorods made no contribution to capacitance enhancement of CS.On the contrary,α-Fe2O3 nanosheets enhanced the capacitance of CS from 172 F g-1 to 294 F g-1.The EIS and conductivity analysis indicate that improving the conductivity of CS-Fe2O3 maight be one of crucial step to leading to an enhanced perofinmace of CS-Fe2O3 electrode.