Study On Structure And Performance Of Binderless NiMn Layered Double Hydroxides Electrode By Intercalation And Sulfide Modification

Electrode materials are the most critical part of supercapacitors and significantly affect the performance of supercapacitors.Among many electrode materials,layered double hydroxides have become a promising electrode material because of its high theoretical capacity,easy synthesis,and considerable energy density and power density.However,the conductivity of layered double hydroxides is poor,and the performance of layered double hydroxides electrodes is restricted by many factors in the preparation by pulping and coating,such as electronic insulation and no electrochemical activity of binder.The preparation of binderless electrodes on conductive substrates has become an effective way to solve the problem.In this paper,binderless NiMn layered double hydroxides electrodes were grown on Ni foam,and the effected of interlayer spacing and sulfidation on the structure,morphology and electrochemical performance of electrode were studied,and to further optimize the electrode performance.The NiMn layered double hydroxides were grown on Ni foam by hydrothermal,and the effected of the amount of sodium dodecyl sulfonate in the reaction system on the structure,morphology and electrochemical performance of electrodes were studied.The results showed that the crystallinity of the samples decreased with the increase of the amount,while the interlayer spacing,growth quality and thickness showed a tendency to increase first and then decrease,and the morphology changed from scattered thin nanosheet arrays to regular thick nanosheet arrays.When the amount was 4 mmol,the interlayer spacing and growth quality of the sample reached the maximum,while the electrode obtains an area capacitance of 6311 m F·cm^-2 at a current density of 5 m A·cm^-2,and an initial capacity retention of 57%after 5000 cycles at 50 m A·cm^-2.The assembled asymmetric supercapacitor has a specific capacitance of 97 F·g^-1 at a current density of1 A·g^-1 and the capacity retention of 85%after 10000 cycles at 10 A·g^-1.Besides,it has an energy density of 35 Wh·kg^-1 and a power density of 11362 W·kg^-1.The sample with the best electrochemical performance in the above was used as precursors,and to further improve the electrochemical activity and conductivity of the electrode by sulfidation,and to explore the effects of sulfidation time on the structure,morphology and electrochemical performance.The results showed that the interlayer spacing of the samples decreased with the increase of sulfidation time and the crystallinity decreased again to a stable value.The samples gradually lose the original clear and regular layers morphology and form sulfides,then the specific surface area gradually increased.After sulfidation for 3 h,the electrode obtains an area capacitance of 9111 m F·cm^-2 under a current density of 5 m A·cm^-2,and an area capacitance is 5346 m F·cm^-2at 100 m A·cm^-2.The assembled asymmetric supercapacitor has a specific capacitance of 133 F·g^-1 at a current density of 1 A·g^-1,and a high-capacity retention of 102%after 10000 cycles at 10A·g^-1.Besides,it has an energy density of 48 Wh·kg^-1 at a power density of 815 W·kg^-1.There are 31 figures,6 tables and 133 references in the paper.