摘要
为了探究多硫离子在多孔碳材料表面的氧化过程,组装了三电极模拟电池和两电极扣式电池。比较了高硫浓度下和低硫浓度下硫电极的循环伏安曲线和充放电曲线;研究了充放电过程中电解液颜色和极片表面颜色的变化;比较了硫浓度、电解液种类、碳材料比表面积对硫电极在2.6 V处氧化峰电流的影响。结果表明:维持硫的适当过饱和度,对硫电极充电过程的完成是必要的;充电过程中可产生单质硫,同时多硫离子还可通过化学过程生成硫。碳比表面积增大,将使氧化峰电流增大;碳酸酯电解液由于对硫和多硫离子溶解度小,氧化峰电流较小;随着硫浓度的增大,氧化峰电流先线性增大,后快速下降。使用醚类电解液时,合适的总硫浓度为0.125 mol/L。
With the aim to shed more light on the reaction mechanism ofrechargeable Li/S batteries, a three electrode set-up and a two electrode coil cell were assembled to identify the possible oxidation process of polysulfides at the surface of mesoporous carbon material. Cyclic Voltammograms and galvanostatic potential profile were examined in high or low sulfur concentrations. The color change in electrolyte and at the surface of positive electrode of a three electrode set-up were studied in the redox process. Factors impact peak current at 2.6 V （vs. Li＋/Li）include concentration of sulfur, component of electrolyte, specific area of carbon matrix were studied. It is necessary to maintain super-saturation of sulfur in electrolyte to complete the charging process;Sulfur is reduced to polysulfides and it dissolves into electrolyte at the discharging process. Polysulfides is oxidized to elemental sulfur, at the same time, it generateselemental sulfur through disproportionation at the charging process. The anodic peak current increases at enhanced area of carbon matrix. It decreases in carbonate electrolyte because the carbonate electrolyte has rather low solubility to sulfur and polysulfides; With the increase of the concentration of sulfur in electrolyte, the anodic peak current first increases proportionally, then decreases dramatically when concentration of sulfur exceeds a certain value. The appropriate total sulfur concentration in ether electrolyte is 0.125 mol/L.
出处
《储能科学与技术》
CAS
2015年第1期61-65,共5页
Energy Storage Science and Technology
基金
国家基础科学人才培养基金(J1103303)项目
关键词
多孔材料
循环伏安
电化学行为
锂硫电池
mesoporous materials： cyclic voltammetry
electrochemical behavior
lithium cells
