Preparation And Electrochemical Properties Of Composites Based On Carbon Cloth

With the development of society,the problem of energy shortage and environmental pollution is more and more serious.It is imperative to develop new energy storage devices with high performance.Meanwhile,electronic products in today's market continue to develop towards the direction of lightweight and portable,so the research of lightweight flexible energy storage devices has also attracted much attention.As an important electrochemical device for energy storage,supercapacitors have the advantages of high charge-discharge rate,good cyclic stability and long service life,and thus supercapacitor is becoming the next generation of energy storage devices with great potential.However,supercapacitors generally have shortcomings such as low energy density,poor conductivity and expensive electrode materials.In order to fundamentally solve these problems,it is necessary to start from the electrode materials of energy storage devices.In this research,a high-performance flexible electrode is obtained by using carbon cloth?CC?with high conductivity and good flexibility.And the composition morphology and electrochemical properties of the electrode were analyzed.Three electrode materials were selected to be compounded with carbon cloth substrate in this paper,NiAl-LDH electrode material with high specific capacity,CoAl-LDH electrode material with high ratio characteristics and manganese dioxide?MnO₂?electrode material with low price.The main results of this research are as follows:1.Preparation and electrochemical properties of NiAl-LDH electrode.The nanoscale NiAl-LDH electrode material was synthesized with carbon cloth as the substrate,and the structure of the electrode was characterized and analyzed.In this study,the NiAl-LDH/CC electrode was compared with the NiAl-LDH electrode without carbon cloth support,and the results showed that the prepared NiAl-LDH/CC electrode had better electrochemical performance.First of all,under the current density of 1A/g,its specific capacity reaches 1540F/g,while under the large current test of 8A/g,its specific capacity is 84.98%under 1A/g,indicating that it has a good multiplier performance.By electrochemical impedance spectroscopy test,showing its low contact resistance?1.2??,charge transfer impedance?1.5??and it also has faster rate of ion transport.Finally,under the current density of 1A/g,after the constant current charging and discharging test of 1000 cycles,the performance after the test is 60%of the initial performance.The unsatisfactory cyclic performance is mainly determined by the expansibility of the nickel base electrode material itself.2.Preparation and electrochemical properties of CoAl-LDH electrode.Because the multiplier performance and cycling performance of the prepared NiAl-LDH/CC electrode are not ideal,in order to obtain the supercapacitor with high multiplier performance and cycling performance,the nano-flake CoAl-LDH electrode material was synthesized and its structure was characterized and analyzed.The results show that the volt-ampere characteristic curves of CoAl-LDH/CC electrode still maintain good symmetry under the high sweep speed of 20mV/s.Meanwhile,the specific capacity of the electrode is 544F/g at the current density of 1 A/g,while it still has the specific capacity of 448 F/g at the large current density of 16A/g,indicating its excellent multiplier performance And the contact impedance was only 0.51?by electrochemical impedance test.Finally,in the cyclic charge and discharge test of current density of1A/g,the specific capacity of CoAl-LDH/CC electrode after 2000 cycles is 83.56%of the initial performance,which indicates that the electrode prepared in this chapter has excellent cyclic characteristics.3.Preparation and electrochemical properties of MnO₂/CC electrode.Low-cost supercapacitors have always been expected in the current market.In the study,carbon cloth was used as a carbon source to grow manganese dioxide in situ,and the effect of reaction temperature on its growth was studied.The experimental results show that the reaction at 60?is not complete,the products are few and have no practical value.And overreaction at 120?leads to poor conductivity of manganese dioxide electrode.By comprehensive comparison,90?is the optimal reaction temperature.The MnO₂/CC electrode prepared under this condition has specific capacity of 249.3F/g at the current density of 0.5A/g.At the same time,after 1000 cycles of constant current charge and discharge test,the specific capacity of the electrode is 69.07%of the initial performance.