| In this paper,The ultivariate vanadate Zn3V3O8 and novel alkaline nickel-base drainage whole battery Ni(OH)2/Bi2O3 were studied.The influence of solvents and additives on synthesis,structure,morphology and electrochemical properties were discussed.The important conclusions were drawn from our expriments.The main contents are as follows:(1)To explore the effects of different solvents on the synthesis and electrochemical properties of Zn3V3O8 products.The ammonium vanadate(NH4VO3)and zinc nitrate(Zn(NO3)2·6H2O)were used as raw materials,the Zn3V3O8 was synthesized under temperature of 200 ? for18h.The solvents used were pure water,water:ethylene glycol =1:1,pure ethylene glycol,and different target products(labeled sample-1,sample-2,sample-3)were obtained.The structure and morphology of products were characterized by X-Ray Diffraction(XRD),Scanning Electron Microscope(SEM)and Transmission Electron Microscope(TEM).The electrochemical performance of the reaction products was tested by battery comprehensive testing system.It was found that when the solvent was mixture(water:ethylene glycol =1:1),the target product sample-2 was pure Zn3V3O8,and its morphology was the sandwich flower like structure of the regular two-dimensional nanoscale,but the products(sample-1 and sample-3)were heterozygous phase and they were taken on morphologies of some nonuniform blocks.The electrochemical performances of the samples were tested under same conditions described above.The discharge specific capacity for former three cycles for sample-2 was 623.9,464.1 and 460.2 mAh g-1 respectively.The discharge capacity of sample-1 and sample-3 is reduced to 240 and 125.5 mAh g-1 in the third cycle.In addition,the specific capacity of the sample-2 after 100 cycles was 666.5 mAh g-1,and the specific capacity was 561.9 mAh g-1 under the large current density of 2 A g-1.Therefore,the Zn3V3O8 synthesized by the mixed solvent method is a promising anode material for lithium io battery.(2)To explore the effect of additives(NH4F and NH4Cl)on the morphology and electrochemical properties of Zn3V3O8.The ammonium vanadate(NH4VO3)and zinc nitrate(Zn(NO3)2 ·6H2O)were used as raw materials,NH4F or NH4CI as 5%wt.of product was added into mixed sovent(water:ethylene glycol =1:1]).The target product Zn3V3O8 was synthesized by a mixed solvent at temperature of 200 ? for 18h,and the products obtained were marked as sample-4 and sample-5.The structures and properties of the samples sample-4 and sample-5'were tested by the same conditions described above.The results show that the product sample-4 was taken morphology of carambola assembled by two dimensional slices,the other product sample-5 was taken morphology of micron flower structure assembled by two dimensional pieces.The electrochemical performance is tested under the voltage range of 0.01-3 V at the current density of 100 mA g-1.The discharge specific capacity of the former three cycles of sample-4 is 1365.1,1065.9 and 1054.7mAh g-1,and the discharge specific capacity of the former three cycles of sample-5 is 887.9,605.5 and 639 mAh g-1 Therefore,the additive of NH4F can lead expected product(Zn3V3O8)to be on special morphology and behave outstanding the electrochemical performance.(3)To explore the effect of the quantity of NH4F additive on the microstructure and electrochemical properties for Zn3V3O8.The additives related to the mass ratio of product 1%,2%,5%,8%and 10%was added into mixed solvent(water:ethylene glycol =1:1)respectively.The target product Zn3V3O8 was synthesized at temereture of 200 ? for 18h.The products were labeled as sample-6,sample-7,sample-4,sample-9 and sample-10 respectively.The structure analysis and performance test were the same condtions described above.The results show that the sample-7 is a uniform two-dimensional thin slice with the thickness of 18-20 nm,and the SEM images are the thin slices with a thickness of 5-8 nm with the largest specific surface area.It is found that larger specific surface area is beneficial to the embedding and removal of the lithium ion and increasing the specific capacity of the products.It is found that under the voltage range of 0.01-3 V at the current density of 100 mA g-1,the discharge specific capacity of the former three cycles of sample-7 is 1709.6,1369.4 and 1304.4 mAh g-1,which is much better than that of the other samples.The specific capacity remaind at 1372 mAh g-1 after 100 cycles.Moreover,under the high current density of 2 A g-1,it still has specific capacity 645.981 mAh g-1.So the optimal quantity of NH4F additive is 2%.Therefore,adjusting the amount of NH4F additive,we can obtain two-dimensional nano thin slices with larger specific surface area,whicn can improve the active sites of lithium ions and electrochemical performance of Zn3V3O8.(4)To explore the influence of surfactants on the electrochemical performance of the novel Ni(OH)2/Bi2O3(Ni-Bi)aqueous battery.The commercial Bi2O3 was used as the Ni-Bi battery anode electrode,and the commercial Ni(OH)2 was used as the cathode electrode of the Ni-Bi battery,and the 6 mol L-1 KOH solution was used as the electrolyte to control the positive negative electrode capacity ratio,and the new alkaline two battery was assembled.A certain amount of surfactant was added into the electrolyte to improve the cycle life and specific capacity of Ni-Bi battery.It was found that the battery system with mass concentration of 1mg L-1 cetyltriethylammnonium bromide(CTAB)solution has higher specific capacity and longer cycle life to 100mL electrolyte.The CTAB solution with mass concentration of 2 mg L-1,5 mg L-1 and 8 mg L-1 respectively was added into the 100 mL 6 mol L-1 KOH electrolyte.It was found that the specific capacity of the battery system adding 5 mg L-1 CTAB reached 230 mAh g-1,which was close to the theoretical capacity of the positive material Ni(OH)2(289 mAh g-1),and the cycle 500 cycles under the current density of 1 A g-1 and the cell specific volume,and the quantity is maintained at 195 mAh g-1.The discharge specific capacity of 150 mAh g-1 remains at 3 A g-1.Therefore,adding the surfactant CTAB to the electrolyte to improve the electrochemical performance of the whole battery in the Ni-Bi aqueous system battery,and the electrochemical performance of the full baterry in the Ni-Bi aqueous system is optimal when the concentration of 5 mg L-1 is added. |
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