Preparation Of Nickel-based Composite Materials And Their Application For Supercapacitors

Supercapacitors are the research hotspots in the fields of energy conversion and storage because of their fast charge and discharge rate,high safety factor and high power density.However,the lower energy density limits the use of supercapacitors.Studies have shown that the specific capacitance of the electrode material and electrochemical window are closely related to the energy density of the supercapacitor.In this paper,nickel-based composite materials are used as electrode materials for supercapacitors.Simple and controllable synthesis methods for nickel-based composite materials are studied.The synergistic effects of different composite materials are studied.From the point of device construction,asymmetric supercapacitors are assembled to increase energy density.First,nickel-based/carbon composites were prepared by using a simple one-step solution combustion reaction.The composition of the composite was controlled by changing the ratio of nickel nitrate to fuel glucose.Nickel hydroxide nitrate was prepared by the solution combustion method for the first time,and the formation mechanism of nickel hydroxide nitrate was proposed.The electrochemical properties of the prepared nickel-based/carbon composites were characterized and analyzed by a three-electrode system.The prepared nickel-based/carbon electrode material has a specific capacity of 1260.0 F/g and 996.0 F/g at a current density of 1 A/g and 10 A/g,respectively.The results showed that the nickel hydroxide nitrate /carbon composite electrode had higher specific capacity and good rate capability.The results show that the nickel-based composites prepared by the solution combustion method have good electrochemical performance,which has certain guiding significance for the preparation of high-performance supercapacitor electrode materials by simple reaction.In order to further improve the electrochemical performance of nickel-based composites,on the basis of the above work,the inorganic salt additives were added to the precursor of the solution combustion reaction,and the composition of the nickel-based composites was further changed by utilizing the catalytic action of inorganic salts.Synergistic effects between composites improve electrochemical performance.In the three-electrode system,the nickelbased composite NC-1.0 synthesized by the salt-assisted solution combustion method has more excellent electrochemical performance than the conventional nickel-based composite NC-0.0 synthesized by the same method.At a current density of 1 A/g,the specific capacity increased from 1260.0 F/g(NC-0.0)to 1420.0 F/g(NC-1.0),and the cycle stability also increased from 53.6% to 60%.This work provides a good reference for the improvement of the simple solution combustion method.Finally,an asymmetric supercapacitor was assembled by using NC-1.0 as a positive electrode material,KOH as an electrolyte and activated carbon as a negative electrode material.Electrochemical analysis of the assembled asymmetric supercapacitor showed that its specific capacitance could reach up to 203.6 F/g.At a power density of 310.2 W/kg,the energy density reached 32.5 Wh/kg.After 1000 cycles,the capacity retention rate is 62.5%.This work has a good impetus for the structural design and optimization of supercapacitors.