Research On The Application Of Anion-intercalated LDHs Nanostructure In Supercapacitors

Climate change and the decreasing availability of fossil fuels require society to move towards sustainable and renewable resources.And energy storage devices are playing a more and more important role in modern society.As a kind of energy storage device with high power density,long cycle life and rapid charge/discharge,supercapacitor is widely used in various fields,but its lower energy density limits its development.Electrode material is a very important part of supercapacitors and is also a major factor influencing its performance.This paper mainly studied the anion intercalated LDH as positive electrode materials for supercapacitors,carbonate ions intercalated into the interlayer of NiAl LDH was prepared,then make it as the precursor to synthesis chlorine ion and nitrate ion intercalated NiAl LDH materials by using ion exchange method.After that,the electrochemical performance of three anion ions intercalated NiAl LDH materials was measured,shows high specific capacity,high rate performance and long cycle life.The details are as follows.?1?NiAl LDH-CO₃^2-was prepared by hydrothermal method by using Al?NO₃?₃ as the aluminium source,NiAl LDH-Cl^-and NiAl LDH-NO₃^-were prepared by ion-exchange method.By comparing three kinds of characterized materials,we found that Cl^-and NO₃^-were intercalated into the interlayer of NiAl LDH successfully,and NiAl LDH-Cl^-had a better flower-like nanosheet structure because of exfoliation and second-assembly process.However,we can draw a conclusion that there was no significant change in the structure and morphology of NiAl LDH with different interlayer anions.?2?electrochemical performance measurement based on three anion-intercalated NiAl LDH by using Al?NO₃?₃ as aluminum source was made.The prepared NiAl LDH-Cl^-material can get the highest specific capacity of 2122 F/g among three materials at a charge-discharge current density of 1A/g,NiAl LDH-CO₃^2-and NiAl LDH-NO₃^-are1138 F/g and 1747 F/g at the same current charge-discharge density respectively,and it retain 92.62%,78%and 78.9%capacity at a charge-discharge current density of 10A/g separately.The prepared NiAl LDH-Cl^-,NiAl LDH-CO₃^2-and NiAl LDH-NO₃^-can retain a 98.29%,75.08%and 87.37%capacity after 500 cycles respectively.?3?AlOOH as a aluminum source,AlOOH-NiAl LDH-CO₃^2-which was assembled into an ellipsoidal structure from single nanosheet was prepared by using a simple hydrothermal method,then using ion-exchange method to synthesis AlOOH-NiAl LDH-Cl^-and AlOOH-NiAl LDH-NO₃^-successively.From the structural and morphological characterization results of three anion-intercalated materials,we can say that no matter what kind of anions are intercalated into the interlayer of NiAl LDH,its structure and morphology will be never changed.?4?Measuring their electrochemical performance of above three intercalation materials using AlOOH as aluminum source is necessary.AlOOH-NiAl LDH-CO₃^2-,AlOOH-NiAl LDH-Cl^-,AlOOH-NiAl LDH-NO₃^-,possessed a specific capacity 1122F/g,1767 F/g,1329F/g at a charge-discharge current density of 1A/g,and can retain84.2%,76.1%,88.9%capacity at a high-rate charge-discharge current density of 10A/g respectively.The prepared electrode of AlOOH-NiAl LDH-CO₃^2-,AlOOH-NiAl LDH-Cl^-,AlOOH-NiAl LDH-NO₃^-given a attenuation about 15.1%,2.55%,22.38%separately after 500 cycles.It demonstrates that AlOOH-NiAl LDH-Cl^-has the best cycle performance,which means it will be a promising positive electrode active materials for supercapacitors.