Preparation And Electrochemical Performance Of [MoO₄] Based Polymetallic Nanoelectrode Materials

Due to the rapid growth of the global economy,the significant increase in fossil fuel consumption worldwide has created two major problems.The first is the accelerated consumption of fossil fuel reserves.And the second is the resulting environmental problems,such as greenhouse gas emissions,air and water pollution.So sustainable development and environmental problem have become the biggest focus.The development and expansion of sustainable clean energy and related technologies is a top priority for global development.However,most renewable clean energy sources are highly dependent on weather conditions.Therefore,energy conversion and energy storage devices need to be developed in order to efficiently store clean energy.Among various energy storage devices,batteries and supercapacitors have become key technologies for energy storage due to their unique advantages.However,batteries have the advantages of high energy density and convenient portability,but their disadvantages are that the power density is relatively low and it is easy to cause safety problems.Compared with batteries,supercapacitors have good cycle stability and high safety,but their main challenge is insufficient energy density,which cannot fully meet the needs of high energy density applications.To overcome this challenge,a lot of work has been done to increase the energy density to expand its range of applications.It is mainly achieved by developing electrode materials with high capacitance,electrolytes with wide potential windows,and integrated systems with optimized structures.This paper is mainly to improve and recombine[MoO₄]-based electrode materials,while improving their specific capacitance and energy density,and also improving their electrochemical cycling stability.The research content and results of this paper mainly include the following three parts.?1?CaMoO₄ microspheres?denoted as CM?were prepared by hydrothermal method,and modified with sodium dodecyl benzene sulfonate?denoted as CMS?.The nano-microspheres were dispersed due to the action of the surfactant.To prevent it from agglomerating tightly,it effectively inhibits the agglomeration of the nanospheres,so that the CMS has a larger specific surface area.In a three-electrode system,the specific capacitances of CM and CMS are 105.3 and 371.4 F g^-1 at scan rate of 2 mV/s,and the discharge time of the CMS is 88.6 s at the current density of 1 A g^-1,but the discharge time of CM is only 54 s at the same current density.After 3000 cycles,the specific capacitance of the CMS has basically no attenuation,with a retention rate of 103%,while the CM has a more serious attenuation,with a specific capacity retention rate of only 79%.?2?ZnMoO₄/NiMoO₄ was synthesized by hydrothermal method at different Zn/Ni molar ratios.The morphology and electrochemical performance of ZnMoO₄/NiMoO₄ were investigated.The experimental results show that the ZnMoO₄/NiMoO₄ electrode material synthesized with a Zn/Ni molar ratio of 1:2?ZNM-4?has a unique hollow microsphere structure with self-assembly,and its unique morphology makes it have unique electrochemical performance.In the three-electrode system,the specific capacitance is 974.6 F g^-1 at current density of 1 A g^-1.The AC//ZNM-4 exhibits a high energy density of 32.5 Wh kg^-1 at a power density of 1059W kg^-1.When the power density is 4938.7 W kg^-1,it still maintains 26.3 Wh kg^-1.The higher energy density indicates that it has good rate performance.And after 3000 cycles,the retention rate of specific capacitance was 92%,and its coulomb efficiency remained above 90%.?3?A composite material of MgMoO₄ and NiO was prepared by a simple hydrothermal method,combining the advantages of both,and the composite material MgMoO₄/NiO has a unique petal-like structure,good electrical conductivity and excellent electrochemical performance.This work mainly explored the morphology and electrochemical performance of MgMoO₄/NiO at different reaction times and temperatures.Through experiments,we know that the optimal reaction temperature and time are 180°C and 8 h.The specific surface area is 59.6 m²/g.In a three-electrode system,the specific capacitance is 537.3 F g^-1 at current density of 0.5 A g^-1.When the energy density of AC//MgMoO₄/NiO is 29.7 Wh Kg^-1,the power density is 865.6 W Kg^-1 and when the power density is 7594.4 W Kg^-1,the energy density is still 17.3 Wh Kg^-1.After 5000 cycles,the specific capacity retention rate was 76%,and the coulomb efficiency remained above 90%.