Preparation Of High Performance MnO₂-based Composite Electrode Material By Thermal Decomposition For Supercapacitor

The development of contemporary technology is unprecedentedly prosperous.The demand for energy is huge,sustainable and environmentally friendly energy is more in line with the green development concept of the time.Among some of the most effective technologies for electrochemical energy storage and conversion,supercapacitors?SCs?,also called electrochemical capacitors,which are capable of storing more energy than traditional capacitors and providing greater power density than batteries while a long cycle life and good safety have generated significant attention.As a new type of clean energy storage and conversion device,the advanced electrode material is the root of supercapacitors.MnO₂ due to its abundant resources,environmental friendliness and excellent electrochemical performance?the theoretical capacitance is 1370F/g?has become a promising material for supercapacitors.But MnO₂ is poor conductivity and has a small specific surface area,which limits its application to some extent.In order to deal with these problems,we use the thermal decomposition method composite MnO₂ with FGS to improve the performance through carbon materials which have good electrical conductivity.In addition,Zn O nanowires were grown on carbon fiber cloth by hydrothermal method,and then amorphous MnO₂ nanoparticles were grown on the surface of Zn O NWs by thermal decomposition.We have established Zn O NWs as the support of the three-dimensional conductive network.The specific work content is as follows:?1?Four different ratios of MnO₂/FGS composite electrode materials were synthesized by a simple one-step thermal decomposition method,their phase composition and microstructure were characterized.In addition,the electrochemical measurements were performed on electrochemical workstations with three-electrode system at room temperature.1M Na2SO4 aqueous solution was used as the electrolyte.According to the Cyclic Voltammetry test,the advantages of the two materials achieve the maximum combination when the ratio of MnO₂ to FGS is 2:1,and the electrode materials exhibit the best electrochemical performance,with a specific capacitance of 102.4 F/g at a current density of 0.5 A/g.It is shown that MnO₂/FGS hybrid materials have important value as electrode material for supercapacitors.?2?Zn O nanowires?Zn O NWs?were grown on carbon cloth via a seed-assisted low-temperature hydrothermal method as substrates to immobilize amorphous MnO₂ nanoparticles which were synthesized by thermal decomposition method,thereby forming three-dimensional hierarchical CC@Zn O@MnO₂ hybrid materials.The hybrid materials could be used as supercapacitor electrodes directly without any binder and conductive additions,which reduces the internal resistance of the materials to some extent,and the equivalent resistance of the hybrid material is 0.558 ?.In 0.5M Na2SO4 aqueous electrolytes,the CC@Zn O@MnO₂ has a high area specific capacitance of 351.5 m F/cm2?and specific capacitance of 585.8 F/g?at a current density of 1 m A/cm2,when the current density is increased to 10 m A/cm2,the area specific capacitance is 205.0 m F/cm2 and the retention is 58.3% of the initial.In addition,the assembled symmetrical button-type supercapacitor has an area specific capacitance of 48.57 m F/cm2,more significantly,the number of charge and discharge cycles is up to 10,000 times,the capacitance retention still maintains 100%.This indicates that CC@Zn O@MnO₂ has outstanding electrochemical properties and is a promising supercapacitor electrode material.In addition,the three symmetrical devices can drive a temperature sensor to work 9 min 22 s,which shows potential application value in the field of electronic equipment.In summary,in this paper,we synthesized high-performance supercapacitor electrode materials through a simple preparation process,and the electrode materials were assembled into devices for practical application.