| Lithium ion batteries?LIBs?have become a very mature and familiar commercial products after years of research and development.However,the commercial lithium ion electrode materials at present can not meet the needs of the market in terms of safety and price.Therefore,it is a new research direction of electrode materials to consider the premise of security issues and improve the energy density,power density,cycle performance and service life at the same time.Vanadium-based phosphate Li3V2?PO4?3 cathode material has become a hot research topic due to its advantages such as good cycle performance,high specific capacity,environmental friendliness,and good safety performance.In recent years,more and more attention has been paid to the improvement of electrochemical performance of lithium vanadium phosphate by different preparation and modification method.With the deepening of the research and mature technology,the cathode materials of lithium vanadium phosphate will be more widely used in the near future.The biological template method is an important technique for the synthesis of nanomaterials,which can be used to synthesize functional materials with special morphologies and excellent properties.The size,shape and structure of the material can be effectively adjusted by the spatial domain and the structure oriented function of the template.The combination of material science and life science inspires people to think about the problem of material science from the angle of life science,and new technology and new materials will be born in the process of research.Natural biological materials have many amazing structures?such as the hierarchical structure as the acme of perfection,nanostructure?,the special structure determines the special function of biological materials?such as biomineralization self-assembly,super hydrophobic etc.?.Therefore,the use of special function and morphology natural biological materials as templates can achieve unexpected results of Materials Science.In addition,the biological template method has played a key role in solving the energy and environmental problems.In a word,the biological template method has a good application prospect and needs further study.In this paper,the Li3V2?PO4?3/C composite cathode material was synthesized by the biological template method and its electrochemical properties were studied and discussed.?1?Li3V2?PO4?3/Ccathode materials were synthesized by using high energy biomolecular template Na2ATP?trinosin?and biological polysaccharide template sodium alginate as template and carbon source.The Li3V2?PO4?3/Li2NaV2?PO4?3/C composites were synthesized with Na2ATP as the template,and the first discharge specific capacity was achieved 158mAhg-1 at 0.1C and a stable voltage platform appeared near the 3.7V voltage.Because of the existence of carbon quantum dots on the surface of the layered electrode material,the conductivity of the material has been significantly improved,even at the 10C rate,the discharge specific capacity can still reach 89.4mAhg-1.Li3V2?PO4?3 precursor was synthesized by sol-gel method by using sodium alginate as a template,and then Li3V2?PO4?3/C composite electrode material was prepared though carbothermal reduction method.The mesoporous carbon has many advantages such as high permeability,permeability and adsorption.Therefore,the electrode material can provide more lithium-ion storage sites relatively and has a great effect on the improvement of the electrical properties of electrode materials.The first discharge specific capacity can reach 129mAhg-1 at 0.1C rate and show good cycle performance.?2?Li3V2?PO4?3/C composites were synthesized by using biomass template corn stalk cores.The natural nanoporous carbon matrix material formed by corn stalk core on the one hand enhances the conductivity of the material,on the other hand as the buffer of mechanical deformation caused by lithium ion implantation and the stability of the material structure is improved.In addition,the active material is distributed in the porous carbon material matrix,which shortens the transmission path of lithium ion,and has a significant influence on the material rate and cycle performance.The discharge specific capacity is 88.7mAhg-1 at 0.5C rate and the discharge specific capacity does not decay after several cycles.?3?The effects of different carbon sources on the performance of electrode materials were investigated:The Li3V2?PO4?3/C cathode material was prepared by using ascorbic acid,glucose and acetylene black as carbon source,and the electrochemical properties were studied.The specific discharge capacities of Li3V2?PO4?3/C electrode materials with ascorbic acid,glucose and acetylene black were 151.2,138.3 and128.2mAhg-1at 0.1C rate,respectively.Among them,the electrode materials with ascorbic acid as the carbon source showed good electrochemical performance. |
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