摘要
采用溶胶 -凝胶法制得钙钛矿型MTiO3 (M =Mg ,Ca ,Sr,Ba)纳米粉体 ,并将所得纳米MTiO3 用于 40 %KOH电解液中MnO2 电极的物理改性 .恒流放电测试结果表明 ,掺杂 5 %的纳米MTiO3 能部分抑制MnO2 电极第二步放电过程中电化学惰性物质Mn3 O4的生成 ,可使MnO2 电极放电提高 40 %以上 ;改性电极的可充性能也得到一定的改善 .循环伏安测试表明 ,在充放电过程中 ,纳米MTiO3 只是填充到MnO2 空隙中 ,并未参与电极反应 ;纳米MTiO3 的掺入改善了电极的传质和传荷环境 ,增大了改性电极的氧化还原电流 ,提高了电活性物质的利用率 ;但经多次循环充放 ,纳米MTiO3 不能有效地阻止MnO2的结构崩溃 。
Nanosized perovskite alkaline earth metal titanates were prepared by sol-gel method. Electrochemical properties of MnO2 electrodes modified with 5% nanosized MTiO3 were investigated by galvanostatic charge-discharge and cyclic voltammetry experiments in 40% KOH solutions. The results from galvanostatic charge-discharge showed that the formation of electrochemically inactive Mn3O4 was partly restrained at the second discharge step, and the discharge capacities of modified MnO2 electrodes were in average 40% higher than that of I. C. No. 1 in heavy/middle load discharge. The rechargeable properties of MnO2 electrodes doped with 5% MTiO3 were also improved to certain extent. Cyclic voltammetric results indicated that nanosized MTiO3 were not involved in electrode reactions during charge-discharge process; but the charge transfer and mass transform of electrodes were enhanced by introduction of nanosized MTiO3. The utilization of electroactive materials increased with the increasing of redox reaction current. Nanosized MTiO3 can not effectively prevent MnO2 lattice structure from being destroyed after several cycles, but they can slow the decreasing rate of discharge capacity.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2003年第11期1797-1802,共6页
Acta Chimica Sinica
基金
国家自然科学基金 (No.2 99630 0 2 )资助项目
