| As a new type of energy storage device,supercapacitor has attracted wide attention because of its advantages,such as its environmental friendliness,long life,high power density and low cost.The electrode material as the key of the supercapacitor is the top priority of the research.Due to its special crystal structure,the basic carbonate cobalt/nickel has attracted extensive research interest in electrochemical electrode materials.In this thesis,three kinds of morphologies of basic carbonate cobalt/nickel nanocomposites were prepared by a simple hydrothermal synthesis method,and their properties were explored in supercapacitors.The main research contents are as follows:1.Synthesis of Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanobelts and their properties in supercapacitorThe Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanobelts with controllable size were successfully synthesized by a hydrothermal method for the first time.And we found that the amount of ammonia added played an important role in controlling the morphology,aspect ratio and phase composition proportion of the Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanocomposites.The obtained nanobelts exhibited superior supercapacitor performance with the specific capacitance of 987 F g-11 at 1 A g-11 and 720 F g-11 at 30 A g-1,respectively,showing an outstanding rate performance（72.9%）.The asymmetric supercapacitor（ASC）assembled by using Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanobelts as positive materials showed a high specific capacitance of 110 F g-11 at 1 A g-11 and 83.3%retention after 5000 cycles,which could provide an energy density of 22.7 Wh kg-11 at a power density of 24019 W kg-1,demonstrating a powerful energy storage capability at high power density for the ASC.Moreover,the assembled ASC exhibited an outstanding flexibility,and its supercapacitor performance hardly changed after undergoing the different bending angles.In addition,the two ASCs in series could illuminate a yellow LED for 15 min.2.Synthesis of Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanoflowers and their properties in supercapacitorBased on the previous experiment,by adjusting the amount of PVP,the flower-like Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanocomposites were synthesized by changing the cobalt-nickel ratio of the reactants.And the morphology and structure of the samples were characterized by SEM,TEM,XRD,FTIR,TG,BET,XPS,EDS,etc.The results showed that the ratio of between cobalt and nickel could affect the phase of the nanocomposite,when the cobalt-nickel ratio was 1:1,the obtained nanocomposite had the best supercapacitor performance.At the current density of 1A g-1,the specific capacitance was 1546 F g-1,and the retention rates was 93.0%and 84.9%from 1 to 10 and 30 A g-1,respectively,exhibiting a superior rate performance.Moreover,the assembled ASC exhibited a high voltage window（1.6 V）,energy density(39.5 Wh kg-1),power density(23955 W kg-1)and bending performance,and it could be used as a power source to light a red LED for 20 min after charging for a few seconds via high current density.3.Synthesis of urchin-like Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 and their properties in supercapacitorThe urchin-like Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 nanocomposites were synthesized by a simple one-step hydrothermal method with urea as both the precipitant and carbon source.The morphology and electrochemical properties of the samples with different cobalt-nickel ratios were investigated,the result displayed that the specific capacitance of the nanocomposites reached 1682 F g-11 at 1 A g-11 and 1333 F g-11 at 30 A g-1,respectively,showing an excellent rate performance（79.3%）,and its retention rate was 96.8%after 2000 cycles.The ASC assembled with Co（CO3）0.5（OH）/Ni2（CO3）（OH）2 had a high voltage window（1.7 V）and energy density(42.5 Wh kg-1),and its energy density could still keep 20.6 Wh kg-1at a high power density of 25511 W kg-1.After the ASC was bent into different angles,it was found that its supercapacitor performance remained well,and the ASC could light a red LED for 25min after charging it for 5 s under high current density. |
