全固态碱性Cd/Ni二次电池的制备及其性能

Preparation of solid state alkaline Cd/Ni second cell and its properties

用溶液浇铸法制备含有聚乙烯醇(PVA)/羧甲基纤维素(CMC)聚合物、KOH和水的复合碱性固态聚合物电解质PVA/CMC/KOH/H2O。采用扫描电镜,循环伏安和交流阻抗技术研究PVA/CMC/KOH/H2O的特性。研究结果表明:在室温时,PVA/CMC/KOH/H2O离子电导率最高可达7.1×10-2S·cm-1;在循环伏安曲线上,在0.15,-0.30和-0.70V时出现明显的氧化还原峰。以PVA/CMC/KOH/H2O为电解质组装的电池,当以1mA/cm2的电流密度放电时,在1.10～1.40V有放电平台出现;当以3mA/cm2电流密度充、放电时,电池经过42次循环后,充、放电效率为88%～95%,表明PVA/CMC/KOH/H2O电解质具有较强的稳定性;电池内阻随着充电过程的进行逐步降低,随着放电过程的进行急剧增大;内阻的增加除了与电极充放电状态有关外,还与外加电场对电解质的影响有关。

A alkaline solid-state polymer electrolyte composed of polyvinyl alcohol(PVA)/carboxy-methylcellulose(CMC) polymer, KOH and H_2O was prepared by solution casting method. The (ionic) conductivity of alkaline composite PVA/CMC/KOH/H_2O polymer electrolyte at room temperature is the highest, 7.1×10^(-2) S·cm^(-1). The morphology and electrochemistry performances of composite PVA/CMC/KOH/H_2O polymer electrolytes were studied by scanning electron (microscope)(SEM), cyclic voltammetry(CV) and alternating current impedance methods, respectively. The results show that there are redox peaks at 0.15, -0.30 and -0.70 V on the CV curves, respectively, and those redox peaks may result from the reaction of active group of the polymer. The discharge voltage plateau of 1.101.40 V at 1 mA/cm^2 was observed for the cell with Ni/Cd electrode and PVA/CMC/KOH/H_2O electrolytes; after the cell being charged/discharged for 42 times at 3 mA/cm^2 , the charge-discharge efficiency is 88%95%. These results indicate that the electrolyte exhibits good stability. It is also found that the inner electric resistance of this cell is decreased in the charge process and significantly increased in the discharge process. The variation of inner electric resistance of this cell is related to not only the charge but also discharge state of electrode and the effect of extra electric field on the solid state electrolyte.