Preparation And Energy Storage Performance Of NiMn-LDH-based Electrode Materials

The application of Ni MN-LDH in supercapacitors has been limited due to poor conductivity and unstable structure during charging and discharging.In order to solve these problems,NiMn-LDH based electrode materials were synthesized by a simple and economical one-step hydrothermal method in this paper.The electrochemical performances of NiMn-LDH based electrode materials were improved by combining with carbon materials and constructing ternary stable structure strategy.The energy storage mechanism and the effect of modification on energy storage performance of NiMn-LDH-based electrode materials were studied systematically,and the performance of its asymmetric supercapacitors also evaluated,the main work and research results shown as follows:（1）NiMn-LDH@MWCNT electrode material with hierarchical structure was synthesized successfully.Its specific capacitance is improved significantly by the wonderful combination of hierarchical structure and carbon skeleton.After optimization,the specific capacity of the NiMn-LDH-4 electrode is as high as 1863 F g^-1(at a current density of 1A g^-1),and even if the current density is increased by 10 times,its specific capacitance can reach 1164 F g^-1.After optimization,the specific capacity of the NiMn-LDH-4 electrode is as high as 1863 F g^-1 at a current density of 1 A g^-1and it can reach 1164 F g^-1even if the current density is increased by 10 times.The main reason for NiMn-LDH-4 electrode with excellent specific capacitance is that its unique hierarchical structure provides larger specific surface area,abundant active sites,and smaller internal mass transfer resistance.In addition,the energy density of NiMn-LDH-4//AC device can reach 51.5 Wh kg^-1 when the power density is 455.7 W kg-¹.（2）NiCoMn-LDH ternary electrode materials with stable structure were fabricated successfully.Among them,the specific capacitance of Ni₃Co_0.3Mn-LDH is the highest,which can reach 1460 F g^-1 at a current density of 1 A g^-1.After 3000 charge-discharge cycles,the capacitance retention rate of Ni₃Co_0.6Mn-LDH is 84.1%at a current density of 3 A g^-1.The higher stability of Ni₃Co_0.6Mn-LDH may be attributed to the structure stabilized by the introduction of Co²⁺between the layers.The energy density of Ni₃Co_0.3Mn-LDH//AC device can reach 9.1 Wh kg^-1 at a higher power density of 3870.7W kg^-1.Moreover,the retention rate of the device is 90%after 5000 charge-discharge cycles,suggesting which has excellent cycle stability.