Preparation Of Nickel-containing Layered Double Hydroxide Based Nanocomposites For High-performance Supercapacitor

Supercapacitor is a new type of energy storage device between traditional capacitors and secondary batteries.Because of the advantages of short-charging time,high power density,long-term cycle life and environmentally friendly,it's widely applied into many fields.Electrode material is the main factor affecting the performance of supercapacitors,so optimizing the performance of electrode materials is the key to the study of supercapacitor applications.Among various structures,graded nanostructure composites supercapacitor materials have unique advantages because they provide a large number of active sites for electrochemical reactions and promote ion transfer in electrochemical processes.As a representative two-dimensional?2D?material,layered double hydroxide?LDH?has received increasing attention due to the adjustability between its composition and morphology.Based on LDH material,combining with metal oxide?MnO₂?and metal organic framework?MOF?for supercapacitor materials,the obtained nanocomposites will have a high specific capacitance and stability,as follows:?1?LDH/MnO₂?NiAl-LDH/MnO₂ and NiFe-LDH/MnO₂?composites were synthesized by hydrothermal method and chemical coprecipitation,and their chemical morphology,composition identification and electrochemical tests were carried out.The results show that the obtained LDH/MnO₂ has good electrochemical performance.At 1 A g^-1,the specific capacitance of NiAl-LDH/MnO₂ is 1092 F g^-1 and the specific capacitance of NiFe-LDH/MnO₂ is 1127 F g^-1.The asymmetric supercapacitor?ASC?was assembled with LDH/MnO₂ as the positive electrode and activated carbon?AC?as the negative electrode,which has an excellent cycle stability.After 10000 cycles at 10 A g^-1,the retention of NiAl-LDH/MnO₂//AC ASC can reach to 90.1%and the retention of NiFe-LDH/MnO₂//AC ASC can reach to 80.5%.Moreover,the maximum energy density of NiAl-LDH/MnO₂//AC ASC is 30.4 Wh Kg^-1 at the power density of 789.8 W Kg^-1.And the maximum energy density of NiFe-LDH/MnO₂//AC ASC is 27.3 Wh Kg^-11 at the power density of 775.5 W Kg^-1.?2?NiAl-LDH/MOF/S nanocomposite was synthesized by hydrothermal method and sulphur treatment,and its chemical morphology,composition identification and electrochemical performance were tested.The results show that the obtained NiAl-LDH/MOF/S composite has good electrochemical properties.At 1 A g^-1,the specific capacitance of NiAl-LDH/MOF/S is 1670 F g^-1.And at 30 A g^-1,the specific capacitance is1086 F g^-1?65%?.The asymmetric supercapacitor was assembled with NiAl-LDH/MOF/S as the positive electrode and activated carbon?AC?as the negative electrode,which has an excellent cycle stability.After 10000 cycles at 10 A g^-1,the retention of NiAl-LDH/MOF/S//AC ASC can reach to 96.4%.Furthermore,it delivers a maximum energy density of 35.4 W h kg^-1 at a power density of 800.0 W kg^-1.