Synergistic Energy Storage Performance Between Metal Compositions Of Nickel-Cobalt-Manganese Based Compounds

The hybrid supercapacitor includes a battery-type electrode and a capacitor-type electrode,has the advantages of the battery and the capacity,and achieves good electrochemical performance with high specific capacity and high specific power.So it has potential application in electric vehicles,portable electronic devices,etc.However,the rate performance and cycling stability of the battery-type electrode is significantly lower than the capacitor-type electrode.The performance difference between the battery-type electrode and the capacitor-type electrode seriously affects the performance of the supercapacitor.It is the key to develop high-performance battery-type electrode material which is helpful to realize the practical application of the hybrid supercapacitor.In the presented paper,the nickel-cobalt-manganese hydroxide and sulfide were prepared and their electrochemical performances were collected to obtain the optimized material with high capacity,high rate and good cycling stability via the content adjustment of nickel,cobalt and manganese in the compounds.The detailed results are as follows:Firstly,the electrochemical synergistic energy storage performance of?-phase nickel-cobalt-manganese hydroxide was studied.The?-phase nickel cobalt manganese hydroxide was prepared by one-step hydrothermal method,and the charge energy storage performance of the hydroxide was optimized by adjusting the manganese content in the compound.In addition,the performances of single-metal,double-metal and nickel-cobalt-manganese?-phase hydroxides were compared to obtain the effect of component design of nickel,cobalt and manganese on the charge energy storage performance of?-phase hydroxides.It was observed that the addition of cobalt and manganese could significantly enhance the specific capacity of the?-phase hydroxide,especially that the cobalt additive could improve the rate performance and cycle stability of the?-phase hydroxide.The specific capacity of?-phase NiCoMn-OH was up to 757 C g^-11 at a current of 1 A g^-11 and 369 C g^-1 at a current of 50 A g^-1,respectively.The hybrid supercapacitor assembled by the?-phase NiCoMn-OH and reduces grapheme oxide achieved a specific capacity of up to 219 C g^-1 and a cycle life of up to 12,000 cycles.The improvement was explained to the electrochemical synergy between the nickel,cobalt and manganese.Then,the electrochemical synergistic energy storage performance of the nickel-cobalt-manganese sulfide was studied.The material was prepared via anion exchange reaction while the?-phase nickel-cobalt-manganese hydroxide was used as a precursor.The electrochemical performance of the nickel-cobalt-manganese sulfide was collected and optimized by adjusting the manganese content in the compound.The nickel-cobalt-manganese sulfide had a specific capacity of 658 C g^-1 at a current density of 1 A g^-1,and the hybrid supercapacitor assembled by nickel-cobalt-manganese sulfide and reduces grapheme oxide retained 94%of the specific capacity after 3000 cycles.Finally,the porous nickel-cobalt-manganese sulfide with different manganese content was synthesized via one-step hydrothermal method and their charge storage performance was compared with single-metal sulfide and double-metal sulfide,in order to elaborate the electrochemical synergistic effect of nickel,cobalt and manganese.The results showed that the porous nickel-cobalt-manganese sulfides had higher capacity than single-metal sulfide and double-metal sulfide,with the optimized value up to 660 C g^-1 at a current density of 1 A g^-1.It had also good cycle stability and the hybrid supercapacitors assembled by the porous nickel-cobalt-manganese sulfides and reduces grapheme oxide maintained a specific capacity value up to 87%after 6000 cycles.