Redox Gel Electrolyte

Cathode and anode electrode materials of redox gelled electrolyte battery has been studied in this work. Ce⁴⁺/Ce³⁺ ion pair has a relative high potential (+1.8 V), and if it is modified by gel method to increase the concentration of reactant, the electrochemical performance can be definitely improved.Three kinds of gelled electrolytes: Ce(CH₃SO₃)₃, Ce(NO₃)₃, and ZnSO₄, were prepared by dispersion, respectively. Content and concentration of SiO₂ effecting viscosity and conductivity performance of gelled has been investigated. Scanning electron microscopy (SEM) was used to study the gelled surface morphology.Based on experimental results, it seems the gelled electrolyte has good surface structure and electrochemical performance when the content of was moderate, and increasing concentration of acid appropriately can improve the conductivity and colloidal gel state. Electrolyte particles dispersed in the get network structure evenly, considerable pore structure can improve diffusion and migration ability, and content of electrolyte.In the case of methanesulfonic acid system, we investigated kinetics of oxidation and reduction reaction of Ce⁴⁺/Ce³⁺ on platinum in 1.5 mol·L^-1 Ce(CH₃SO₃)₃ + 2 mol·L^-1 CH₃SO₃H electrolyte. Kinetics parameters of reaction were calculated from polarization curves: diffusion coefficient D=5.89×10^-6cm²·s^-1, transfer coefficientα=0.3845,β=0.26, exchange current density i_a⁰=2.75×10^-3mA·cm^-2, i_c⁰=5.13×10^-3mA·cm^-2.In the case of nitric acid system, we studied kinetics of oxidation and reduction reaction of Ce⁴⁺/Ce³⁺ on platinum in 1.5 mol·L^-1 3 mol/L Ce(NO₃)₃ + 2 mol/L HNO₃ electrolyte. Calculated kinetic parameters were: transfer coefficientα=0.7755,β=0.2175, exchange current density i_a⁰=1.74×10^-3mA·cm^-2,i_c⁰=4.99×10^-4mA·cm^-2.The performance of two different acid system gelled batteries was studied by assembled to batteries. By comparison of charged-discharged performance of these two kinds of batteries, we found out that In high current charging condition, coulombic efficiency is high as well.In low current charging condition, coulombic efficiency is low, but voltage efficiency is high.Seen from energy efficiency aspect, gelled battery is suitable for high current charging.According to results of cycling tests, methanesulfonic acid system has good repeatability, but nitric acid system has high specific energy.In a word, the promising gelled electrolyte Ce-Zn can be used in the gelled batteries, it's possible to be applied in near future.