Study On Modification,Composite And Capacitance Of NiTi Layered Double Hydroxide

The electrode material of supercapacitor is one of the indexes that determine its performance,and hydrotalcite becomes one of the electrode materials of supercapacitor due to its redox reaction can provide large specific capacity,and hydrotalcite also has the characteristics of adjustable lamellar cation and interlamellar anion,low cost,friendly environment and so on.However,due to the effect of electrostatic force,it is easy to accumulate between the layers of hydrotalcite in the synthesis process,and the hydrotalcite itself is a semiconductor material,and its conductivity is poor,so it is difficult to reach its theoretical specific surface area and specific capacitance.Therefore,by improving the specific surface area of hydrotalcite and adding different metal elements,the effects of specific surface area and adding elements on the specific capacitance,scaling performance and cycling performance of the electrode materials were analyzed.In this paper,NiTi layered double hydroxide（NiTi-LDHs）was prepared by one-step hydrothermal method,and the optimum ratio was obtained by adjusting the molar ratio of Ni-Ti.and the best Ni:Ti is 3:0.5.On this basis,the reaction synthesis time was controlled to find the best NiTi-LDHs reaction time.With the increase of Ti⁴⁺,the layer spacing decreases gradually.When Ni:Ti=3:0.5,the most uniform flower-like morphology and the best capacitance are obtained.the specific capacitance is 1569.09F/g at the current density is1A/g,and the specific capacitance is 181.81F/g at the current density is 20A/g.The capacitance retention rate is 22.4%after 1000 cycles at the current density of 10A/g.Based on the optimal proportion and time of NiTi layered double hydroxide,NiTi Al layered double hydroxide（NiTi Al-LDHs）were prepared by one-step hydrothermal method.The optimum synthesis time and molar ratio of NiTi Al-LDHs were found by adjusting the hydrothermal synthesis time and molar ratio.With the increase of hydrothermal synthesis time and Al content,the crystallinity becomes higher and higher,and the best Ni:Ti:Al=3:0.5:0.1.On this basis,the NiTiAl-LDHs was etched with 5mol/L NaOH solution for 10h,18h and 24h,respectively.With the increase of etching time,the reversibility of redox reaction becomes better and better,and the specific surface area increases first and then decreases.When the etching time reaches 18h,the specific surface area reaches the maximum,which is 203.59m²/g.The specific capacitance is 1979F/g at the current density is 1A/g,and the specific capacitance is 551.72F/g at the current density is 20A/g.The capacitance retention rate is 38%after 3000 cycles at the current density of 10A/g.NiTiCo layered double hydroxide and TiO₂composite（NiTiCo-LDHs/TiO₂）was prepared by one-step hydrothermal method.The ratio performance and long cycle performance of NiTi-LDHs were improved by adding Co element.With the increase of co content,the capacitance performance first increased and then decreased,and the best Ni:Ti:Co is 3:0.5:1,the specific capacitance is 1787F/g at the current density is 1A/g,and the specific capacitance is1018F/g at the current density is 20A/g.The capacitance retention rate is 69.6%after 2000cycles at the current density of 20A/g.The paper has 30 pictures,6 tables and 108 references.