正极材料单质硫在LiCF_3SO_3/DOL+DME电解液中的放电性能

Discharge performance of cathode material elemental sulfur in LiCF_3SO_3/DOL+DME electrolyte

研究了单质硫在1 mol/L LiCF3SO3/DOL+DME电解液中的倍率放电性能。结果表明:单质硫的首次放电容量随着放电倍率增大呈现先增后减的趋势。单质硫具有良好的充放电性能,在0.6 mA/cm2的充放电电流密度下,首次放电比容量为972 mAh/g,第50次循环的放电比容量达到605 mAh/g。单质硫的低电压平台能够提供约70%的放电总容量,但低电压平台容量衰减速率较快,平均容量衰减率为0.8%。循环伏安实验的结果表明:在1 mol/L LiCF3SO3/DOL+DME电解液中,单质硫的还原反应为浓差扩散过程,在峰电位1.90 V低电位处的第2还原反应产生固相硫化锂,引起电极钝化现象。

Rate discharge performance of elemental sulfur in 1 mol/L LiCF3SO3/DOL ＋ DME electrolyte was investigated. The results showed that the initial discharge capacity increased at first and then decreased with the discharge current density increasing. Elemental sulfur exhibited a favorable charge-discharge performance, the initial discharge specific capacity was 972 mAh/g and the discharge specific capacity at the 50th cycle was 605 mAh/g at the charge-discharge current density of 0.6 mA/ cm^2. The low discharge voltage plateau for elemental sulfur could offer about 70% of total discharge capacity, however, the low discharge voltage plateau capacity fading was more serious and average capacity fading rate was 0.8 %. The CV experiment result indicated that the reduction of elemental sulfur in 1 mol/L LiCF3SO3/DOL ＋ DME electrolyte was affected by a diffusioncontrolled process, the second reduction located in low potential range of 1.90 V （peak potential） resulted in solid phase lithium sulfide and passivation phenomenon of the electrode.