Study On The Preparation And Chemical Energy Storage Of Vanadium And Manganese-Containing Oxides/Carbonate

Rechargeable lithium-ion batteries have developed into a major energy storage technology and are widely utilized in portable electronic devices such as smartphones and laptops,as well as in electric vehicles,military and aerospace applications.With the increasing energy demand,the energy capacity,and power density of lithium-ion batteries have become the bottleneck of battery technology,especially the low capacity and slow charge/discharge kinetics of the active electrode materials hinder the further improvement of performance.Transition metal oxides/carbonates based on conversion reactions are promising anode materials for lithium-ion batteries due to the low production cost,high safety,ease of operation,and high theoretical capacity.Meanwhile,transition metal oxide/carbonate anode materials also have defects such as low electrical conductivity and poor cycling stability.Based on the above research,a series of high performance anode materials with high specific capacity,good rate performance and long cycle life were prepared by rational design of the composition and structure of vanadium,manganese-containing oxides/carbonates.（1）Study on the preparation and energy storage properties of V₂O₅ porous microstructures.Nest-like shape and spherical shape V₂O₅ porous microstructures were successfully prepared by solvothermal and calcination processes,and the electrochemical properties were investigated as active materials for lithium-ion batteries.The novel structure endows the electrode materials shorter diffusion pathways and contributes to the transport of Li⁺-electrons.For the formed V₂O₅ porous microspheres electrode,a stable reversible specific capacity of 989.8 m A h g^-1 can be obtained at 0.5 A g^-1 after 350 cycles.As the current density gradually increases to 5.0 A g^-1,the reversible capacity still maintains at 426.2 m A h g^-1.These characteristics prove that the formed V₂O₅ porous microspheres present a wide application prospect in the field of portable energy storage device.（2）Study on the preparation and energy storage properties of hierarchical Mn₂V₂O₇.Binary transition metal oxide Mn₂V₂O₇ nanoplates and nanosheet-based hierarchical microstructures were prepared by changing the molar ratio of NH₄VO₃and KMn O₄in the initial reaction system through the solvothermal method.As the anode active materials of lithium-ion batteries,the electrochemical properties of both formed Mn₂V₂O₇ structures were investigated.After 300 cycles at 0.5 A g^-1,Mn₂V₂O₇ nanoplates and nanosheet-based hierarchical microstructures could maintain discharge capacities of 1014.3 and 1096.0 m A h g^-1 respectively.At the higher current density of 5.0 A g^-1,the reversible capacities of388.3 and 608.6 m A h g^-1 could still be obtained for the Mn₂V₂O₇ nanoplates and nanosheet-based hierarchical microstructures after 500 cycles.The nano-sheets structures shorten the transmission paths of ions and electrons,while the synergistic effect occurred between manganese and vanadium elements also enhance the electrochemical activity.Therefore,the manganese vanadium oxide materials prepared in this study exhibit great prospects for application in energy storage devices.（3）Study on the preparation and energy storage properties of Cu²⁺-doped Mn CO₃.A simple,low cost and green hydrothermal process has been proposed to prepared Cu²⁺-doped Mn CO₃ microparticles.The Cu²⁺-doped Mn CO₃ microparticles with rhombohedral and olive shapes were successfully synthesized by varying the addition amount of Cu（NO₃）₂·3H₂O in the initial reaction system.The composition and morphology were characterized by various means.As the anode active materials for Li-ion batteries,both of rhombohedral and olive-shaped Cu²⁺-doped Mn CO₃ microparticles exhibit excellent cycling performance.The rhombohedral and olive-shaped Cu²⁺-doped Mn CO₃microparticles still maintain reversible capacities of 619.4 and 823.5 m A h g^-1 over 1000cycles at 0.5 A g^-1,demonstrating outstanding advantages for application in high-performance energy storage devices.