Preparation Of N/S Doped Superc-apacitor Electrode Materials And Its Electrochemical Performance

Supercapacitor with fast charge and discharge speed,high power den-sity and long cycle life is considered to be one of the most promising en-ergy storage devices at present.However,various electrode materials that play a decisive role in the performance of supercapacitor face some prob-lems,such as the small specific capacitance and low energy density（<10Wh/Kg）of carbon materials;the poor cycling stability of metal oxides;small specific capacitance of Co（OH）₂ and short life of Ni（OH）₂ in hy-droxide.Research shows that the electrochemical performance can be ef-fectively improved by doping heteroatoms（N,O,S,B,P）.In this paper,the electrode materials are prepared by doping nitrogen in carbon materi-als,sulfur in metal oxides and hydroxides,and a series of test methods are used to study the physical and electrochemical properties of materials.The main research contents are as follows:（1）The nitrogen-containing organic ligand 2,6-bis（2-pyrazinyl）-4-（4-（tetrazol-5-yl）phenyl）pyridine and the metal organic complexes pre-pared by the reaction of the ligand with zinc salt are used as precursors respectively,the nitrogen-doped carbon materials Z-700 and Y-700 are obtained by heat treatment in N₂ atmosphere.At the current density of 0.5A/g,the specific capacitance of Z-700 is 218.6 F/g,energy density up to43.7 Wh/Kg and the specific capacitance of Y-700 reaches 276.5 F/g,en-ergy density is 38.4 Wh/Kg.At 10 A/g,the capacitance retention rate of Z-700 is 107%after 100000 cycles of charge and discharge;and the ca-pacitance retention rate of Y-700 is 91%after 89000 cycles of charge and discharge.（2）Using thiosalicylic acid as ligand,Co²⁺and Ni²⁺are provide by CoCl₂?6H₂O and NiCl₂?6H₂O,and nickel-cobalt bimetal oxide compo-site A is obtained by hydrothermal synthesis and calcination.The mass ratio of A and thioacetamide is controlled,and the nickel-cobalt bimetal sulfide composite is obtained by hydrothermal vulcanization.The test found that the best vulcanization quality ratio is 1:3.At 10 A/g,the spe-cific capacitance of the sulfide composite material obtained under these condition is 750.4 F/g;at 5 A/g,the capacitance rate is 82.1%after 5000cycles of charge and discharge.（3）Ni（OH）₂ and Co（OH）₂ are prepared by chemical precipitation us-ing NaOH and NiCl₂?6H₂O,Co（NO₃）₂?6H₂O as raw materials,and sul-fur-doped Ni（OH）₂ and Co（OH）₂ are prepared from different sulfur sources.At 20 A/g,the specific capacitance of Ni（OH）₂ is 750.6 F/g;at 3A/g,the capacitance retention rate is only 46%after 1000 cycles of charge and discharge.At 3 A/g,the specific capacitance of Co（OH）₂ is127.8 F/g,the capacitance retention rate is 90%after 20000 cycles.After sulfur doping,at 20 A/g,the specific capacitance of Ni（OH）₂（Na₂SO₄）is652.4 F/g;at 3 A/g,the capacitance retention rate is 60%after 1000 cy-cles;at 3 A/g,the specific capacitance of Co（OH）₂（Na₂SO₄）is 268.2 F/g,the capacitance rentention rate is 89%after 20000 cycles of charge and discharge.