| With the continuous consumption of fossil fuels and the gradual intensification of greenhouse effect,energy shortage and environmental pollution have become two major problems facing the sustainable development of human society.In recent years,the rapid development of the lithium ion battery industry and the low reserves of lithium resources have caused the overall cost of lithium ion batteries to rise.With the progress towards the goal of carbon peak and carbon neutrality,the environmental problems caused by the organic electrolyte used in lithium-ion batteries have been gradually paid attention to.The emergence of zinc-ion battery in water system can well solve these two problems.Zinc-ion battery in water system can overcome the limitations of conditions and become one of the best candidates for large-scale energy storage system(ESS)due to the safety of electrolyte,environmental protection,high negative zinc storage,high capacity,low cost and low potential.At present,one of the main bottlenecks limiting the development of zinc-ion batteries in water systems is the lack of positive electrode materials with stable structure and suitable for zinc ion deintercalation.Vanadium series materials stand out from many positive electrode materials because of their good layered structure and excellent specific capacity.In view of the low electrical conductivity and instability of vanadium system materials,this paper can start from the aspects of preintercalation strategy,lattice doping strategy,morphology improvement and composite material construction,and adopt one or more of the strategies to improve the comprehensive performance of the materials,and study the electrochemical performance and zinc storage mechanism of vanadium system materials in the process of REDOX.In order to solve the problem of low specific capacity of V2O5 material,the material NVO with nickel ion preembedded in vanadium pentahydrate was prepared by hydrothermal method.Firstly,the optimal reaction conditions were obtained by exploring different nickel sources,adjusting the feeding sequence and adjusting the reaction time.Second,the NVO material was characterized by morphology and electrochemical test.The results showed that the nickel ion insertion not only expanded the layer spacing,but also the dispersion of intercalator caused the material morphology to change and increased the zinc ion embedding site,thus improving the specific capacity of the material.When the current density is 0.3 A g-1,the specific capacity can reach 488.3 mAh g-1,but the capacity retention rate is only 56.9%.At A large current of 8 A g-1,the specific capacity of 195 mAh g-1 can be maintained after 500 cycles.In view of the low cyclic stability and poor electrochemical performance of V2O5 material,the Ni-Lithium bimetallic ion modified vanadium oxide material LNV-20/10 was prepared by means of lattice doping and metal ion preembedding strategy.Firstly,nickel ions were doped into the lattice of vanadium pentahydrate by calcination,and then lithium ions were embedded into the interlayer by hydrothermal method to stabilize the laminate structure.During the electrochemical test,the 10%Ni-V2O5 doped with nickel ion lattice has A specific capacity of 450 mAh g-1 at a current density of 0.1 A g-1,but the capacity retention rate is only 60%after 50 cycles.The Li+intercalation stabilization strategy was adopted to optimize the doped Ni ion lattice.After the optimization strategy,the material LNV-20/10 maintained a capacity of about 530 mAh g-1 at 0.3 A g-1,and could still maintain a specific capacity of 329 mAh g-1 after 400 cycles at a current density of 3 A g-1,and the capacity retention rate reached 89.8%.To sum up,the electrochemical performance of vanad based oxide materials can be effectively improved by adopting this strategy of metal ion preembedding combined with lattice doping,which also provides a new research idea for the research and development of advanced energy storage materials. |
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