温度对锂硫电池放电过程的影响

为深入研究液相扩散过程对锂硫电池放电过程的影响,采用充放电测试、循环伏安测试了不同温度下锂硫电池的电化学性能,采用电子扫描显微镜观察分析了不同温度下放电后的正极形貌.实验结果表明,温度降低引起电解液粘度增加,离子在电解液中的扩散系数降低；当温度低于10℃时,锂硫电池的放电性能明显恶化,低放电平台容量的降低是电池性能恶化的主要原因.循环伏安测试分析表明,锂硫电池的低放电平台是扩散控制过程,受温度影响较大.离子在电解液中的扩散过程受限引起碳骨架的钝化,进而造成低放电平台活性物质未充分反应,这是锂硫电池放电过程受温度影响的主要原因.

Effect of temperature on discharge process of lithium sulfur batteries

The electrochemical properties of lithium sulfur batteries at different temperature were investigated by charge-discharge and CV(Cyclic Voltammetry) for probing into the effect of the liquid diffusion process on discharge process of the lithium-sulfur batteries.Surface morphology of sulfur cathodes was observed by SEM(scanning electron microscope).The surface of sulfur cathode was covered by a solid film in low temperature.It suggests that low temperature results in the decrease of diffusion coefficient and diffusion flux of electrolyte for the battery.The discharge properties of lithium sulfur batteries worsens obviously at less than 10 ℃ and below,and the decrease of low plateau specific capacity was mostly the cause of the worsening.The cyclic voltammetry showed that low plateau of discharge process was strongly affected by temperature because it was a diffusion-controlled process which can lead to polarization in cathode.The increase of diffusion resistance of ion in electrolyte caused the passivation of the carbon matrix,the passivation resulted in inadequate reaction of active material in low plateau,that is mostly the cause of the effect of temperature on discharge process of lithium sulfur batteries.