Font Size: a A A

Electrochemical Treatment Of Nickel Foam Current Collector And Fundamental Research Of Its Energy Storage Property

Posted on:2014-04-13Degree:MasterType:Thesis
Country:ChinaCandidate:F ZhangFull Text:PDF
GTID:2252330425475827Subject:Electronic materials engineering
Abstract/Summary:PDF Full Text Request
As a new type of energy storage device, supercapacitors have the large power density,stable performance during charge and discharge, etc. and are widely used in the field ofelectric hybrid cars and digital communication equipment, etc. Current collector is animportant part of the electrode for supercapacitors. With the characteristic of high porosity,large specific surface and stable performance in alkaline solution, nickel foam is often used ascurrent collector materials. Usually, the electrochemical properties of current collector ofnickel foam can be neglected because of the small capacitance from low specific surface areaand loss mass of active material growing in alkaline electrolyte. In this thesis, the fundamentalresearch of the electrochemical characteristics of nickel foam was performed and theinfluence of electrochemical treatment on the capacitance of nickel foam was investigated.Cyclic voltammetry cycling was performed on the nickel foam with different electrolyteconcentration and temperatures, and the results show as follows: a thin layer ofα-Ni(OH)2wasin-situ grown on the surface of nickel foam in the alkaline solution and the CV curve showedtypical oxidation-reduction reaction; the potential of oxidation-reduction reaction forα-Ni(OH)2shifted to negative potential with the increasing electrolyte concentration orworking temperature, and β-Ni(OH)2was found at high electrolyte concentration and hightemperature; the highest areal specific capacitance for nickel foam was obtained at6M KOHsolution. The more results showed no improvement on the capacitance of nickel foam fromconstant voltage processing and heat treatment.In this thesis, electrochemical treatments on the nickel foam in strong acid and alkalinesolution were performed, and the results showed as follows: anodic oxidation was performedon the nickel foam in electrolytic solution consisting of85%phosphoric acid and0.5Mammonium fluoride; the areal specific capacitance increased with increasing potential at thesame charge transfer and the high areal specific capacitance of0.92F/cm2(scan at10mV/s)was obtained at6V; the SEM photographs indicated that obvious coarsening effect on thesurface of nickel foam. Negative cyclic voltammetry scanning (-1.5V-1.2V) was carried outin6M KOH solution, and the results showed that: the areal specific capacitance increasedwith the increasing cycles for negative CV cycling; the areal specific capacitance increased from0.11F/cm2to2.8F/cm2after1650negative cycles (scan at10mV/s); the improvementof the performance was due to the surface roughing from the lattice expansion and contractioncaused by oxidation-reduction cycling between Ni and Ni(OH)2, and the micro-channel fromhydrogen infiltrating/precipitating in the surface of the nickel.
Keywords/Search Tags:Supercapacitor, Nickel foam current collector, Cyclic voltammetry scanning, Anodic oxidation
PDF Full Text Request
Related items