The Preparation And Electrochemical Performances Of Nickel And Vanadium Hydrotalcite And Its Carbon Composite Material

In today’s increasingly serious energy crisis, supercapacitor is safe, reliable, green environmental to become the hot spot in the research object, supercapacitor electrode material is an important part to determine the electrochemical properties. At present, the supercapacitor research emphasis is still a development for high specific capacity, high energy density and power density, good conductivity, stable structure of electrode materials.This paper introducing vanadium metal elements of excellent electrochemical activity to nickel hydroxide layer board successful to synthesis of high specific capacity of nickel and vanadium hydrotalcite, then hydrotalcite and a highly conductive carbon composite material consisting of structural stability, high-performance composite electrode material is successful synthesized, specific work is as follows:1. A series of different proportion of metal carbonate intercalated nickel and vanadium hydrotalcite （NixV-LDH） were synthesized by coprecipitation, Structure and Morphology Characterization results show that the incorporation of nickel hydroxide laminates consisting of nickel and vanadium vanadium hydrotalcite compared with the nickel hydroxide, crystalline laminate structure better and more regularity. And with the increase in nickel and vanadium hydrotalcite molar ratio, laminates gradually become regular. The electrochemical properties of vanadium element is introduced into the electrochemical properties of the nickel hydroxide has a good effect, and different vanadium element doping amount of nickel and vanadium hydrotalcite performance difference. As vanadium doped quantity increase, specific capacity gradually increased, cycle stability decreased. Ni/V molar ratio of 2:1 has the highest specific capacity, specific capacity up to 1096F · g ^-1, with a capacitance retention up to 80% after 500 cycles under the current density of 5 A·g^-1, stability and rate performance has a lot of improvement compared to nickel hydroxide, good performance under high current density, it attributed to resistance decrease after introduction of vanadium.2. A series of different compound ratio of Ni2V-LDH/CNT composites synthesized by coprecipitation, containing different amount of functionalized carbon nanotubes and nickel and vanadium hydrotalcite. Good electrical conductivity and structure stability of carbon nanotube and high specific capacity of nickel and vanadium hydrotalcite promote good electrochemical performance of composite materials. With the increase of the amount of carbon nanotubes, specific capacity of composite materials increase first and then decrease, the change rule of this is because the contribution of carbon nanotubes is electric double layer capacitor, and the contribution of hydrotalcite is Faraday constraint capacitance, specific capacity of the composite mainly depends on the contribution of hydrotalcite, increase a certain proportion carbon stuff with good electrical conductivity is helpful to the promotion of hydrotalcite specific storage, but if too much, because relatively reduce the proportion of hydrotalcite and makes specific capacity decline. Among three ratio in composite materials, Ni2V-LDH/CNT mass ratio of 80:3, the highest specific capacity, cycle stability and rate performance is best. Under the current density of 5A·g^-1, the specific capacity is 1125 F · g^-1,retention up 86% after 1000 cycles.3. With traditional hummers method, different oxidation degree of oxidation of acetylene black obtioned by controlling the oxidation treatment temperature and time. Then through coprecipitation method in different oxidation degree of acetylene black on the surface of in situ growth nickel and vanadium oxide hydrotalcite get four Ni2V-LDH/C composite material, morphology characterization show nickel and vanadium hydrotalcite is generated in the surface of the acetylene black, low degree of oxidation of acetylene black anchor the generation of hydrotalcite is more spread out, and the lamella is larger, and the high degree of oxidation of acetylene black anchor generation hydrotalcite tablets more accumulation, small slice layer. Four kinds of composite materials in 1 MKOH electrolyte showed good electrochemical performance, given a present first increases then decreases, the change rule of this is because the conductivity of the acetylene black increased material, oxygen acetylene black anchoring effect reduced water talclamella reunion, further improve the electrochemical properties, but the high degree of oxidation of acetylene black too much oxygen containing functional groups and as a result of the surface will be reunited, which in 90 ℃ treatment 1 h of acetylene black nickel and vanadium hydrotalcite composite electrochemical performance is the most excellent, at 5 A·g^-1, initial specific capacitance is 865.46 g F·g^-1, cycle given to keep 89% after 1000 weeks, charge and discharge current density at 9 A·g^-1, initial specific capacitance of 703.94F·g^-1, keep 70% capacity after 1000 cycles, performance under the condition of high current density. Compared with carbon nanotubes, the oxidation of acetylene black cost is lower, the hydrotalcite dispersion effect is more apparent, show more excellent performance.