微型超级电容器的漏电流特性研究

Study on Leakage Current Characteristics of Micro-supercapacitor

针对微型超级电容器自放电产生的电流泄漏问题较为严重的问题,对基于PPy/GO材料体系的微型超级电容的结构和漏电流特性进行了研究。采用微纳加工工艺设计制作的微型超级电容结构紧凑耐冲击,膜电极微观形貌呈片状,比表面积较大。测量了微型超级电容在充放电过程中的电压、漏电流和自放电数据,从欧姆泄漏、法拉第反应,以及过电压引起的自放电机制的角度,对微型超级电容器漏电流的产生机理进行分析。结果表明:欧姆泄漏引起的漏电流值在低电压工作范围内呈现为线性;电极材料或电解液中含有化学活性的任何杂质是产生法拉第自放电泄漏电流的主要因素;依据电压、漏电流特性曲线和凝胶电解质的电化学稳定窗口,明确了微型超级电容器可正常工作的电压范围为0.1~2.5 V;采用较高充电电压会使法拉第反应速率加快,致使漏电流增加。通过测量在充放电过程中的电压、漏电流的变化形式为识别微型超级电容器的自放电过程提供了一种技术手段。

In view of the serious problem of current leakage caused by self-discharge of micro-super capacitor,the structure and leakage current characteristics of micro-super capacitor based on PPy/GO material system are studied.The micro-supercapacitor,designed and manufactured by adopting micro nano processing,is compact in structure and resistant in shock.The micro morphology of the membrane electrode is flaky and of large surface area.The voltage,leakage current and self-discharge data of the micro-supercapacitor during the charge and discharge are measured.The generation mechanism of leakage current of the micro super capacitor is analyzed from the perspective of ohmic leakage,faraday reaction and the self-discharge motor system due to overvoltage.The result shows that the leakage current due to ohmic leakage is of linear in the low voltage operating range.Any impurity containing chemical activity in the electrode material or electrolyte is the main factor to produce the leakage current of Faraday self-discharge.The normal operating voltage range of the micro super capacitor is defined between 0.1~2.5 V in accordance with the voltage and leakage current characteristic curve and the electrochemical stability window of gel electrolyte.The Faraday reaction rate is accelerated and the leakage current is increased by using higher charging voltage.A kind of technical measure for identifying the self-discharge process of the micro supercapacitor is provided by way of measuring the variation of voltage and leakage current in the process of charge and discharge.