Preparation Of Nickel-manganese Hydrotalcite-based Electrode Materials And Property For Supercapacitor

With the rapid growth of population and the deteriorating environment,electrical energy is widely used as a renewable secondary energy source.Therefore,the development of energy storage components is becoming more and more important,among which supercapacitors occupy an important position.The electrochemical performance of supercapacitors mainly depends on electrode materials.Hydrotalcite(LDH)exhibits high specific capacitance and good stability due to its unique laminate structure,adjustable host-guest composition and highly dispersed active sites.The multi-dimensional LDH-based electrode materials were constructed to further improve their charge transfer and surface reactivity to obtain electrode materials with excellent performance.In this thesis,a series of LDH with special structures,sulfides and composites with LDH-based materials were prepared by means of metal doping,in situ growth,sulfidation and surface modification to effectively improve the electrochemical properties of Ni-Mn-based LDH,and the main research results are as follows.(1)Co²⁺-doped NiMn-LDH electrode material(NiCoMn-LDH)was prepared by hydrothermal method,and the optimal Co²⁺doping amount was determined to investigate the mechanism of the effect of Co²⁺doping on NiCoMn-LDH.The electrochemical performance tests showed that the electrode material significantly enhanced the supercapacitance performance with a specific capacity of 443.4 C·g^-1 at a current density of 1.0 A·g^-1;at 5.0 A·g^-1,and the capacitance retention was at 90.12%after 2,000 cycles of testing.(2)NiCoMn-LDH was grown in situ on Nifoam(NF)to produce NiCoMn-LDH/NF precursors,and NiCoMn-LDH nanosheets were interdigitated and grown perpendicular to the NF surface.Then NiCoMn-LDH/NF precursors were vulcanized to finally obtain NiCoMn S/NF electrode materials.It is shown that the NiCoMn S morphology structure can be adjusted by modulating the S^2-concentration,and among them,the maple spherical NiCoMn S shows excellent electrochemical properties.The specific capacitance was 874.7 C·g^-1 at a current density of 1.0 A·g^-1,and the specific capacitance retention was 87.73%at 5.0 A·g^-1tested for 2,000 cycles.The maximum energy density of 47.17 Wh·kg^-1 was obtained for NiCoMn S/NF//AC at a minimum power of 750.00 W·kg^-1.(3)The?phase NiCoMn-LDH was prepared hydrothermally using hexamethylene tetramine(HMT)as the base source to investigate the mechanism of Co²⁺doping on the?-NiCoMn-LDH.?phase NiCoMn-LDH was superior to the NiCoMn-LDH,with the specific capacitance at 1.0 A·g^-1 at a current density of 637.0 C·g^-1;the specific capacitance retention was at 87.68%after 2,000 cycles tested at 5.0 A·g^-1.(4)NiCo₂O₄ precursor was deposited on NF to produce NiCo₂O₄/NF precursor,and then?phase NiCoMn-LDH was wrapped on the precursor surface to produce NiCo₂O₄@?-NiCoMn-LDH core-shell material to probe the interaction mechanism between?phase NiCoMn-LDH and NiCo₂O₄.The specific capacitance was 1035.0 C·g^-1 at a current density of1.0 A·g^-1,and the specific capacitance retention rate was 92.66%after 2,000 cycles tested at 5.0A·g^-1.NiCo₂O₄@?-NiCoMn-LDH//AC obtained a maximum energy density of 61.34 Wh·kg^-1at a minimum power of 850.00 W·kg^-1.