苯硫酚盐基溶液的可充镁电池电解液

Benzenethiolate-Based Solutions for Rechargeable Magnesium Battery Electrolytes

将4-甲基苯硫酚、4-异丙基苯硫酚和4-甲氧基苯硫酚(RSH)分别与格氏试剂C2H5MgCl/THF(四氢呋喃)反应制得的苯硫酚氯化镁(RSMgCl)(分别标记为MBMC、IPBMC和MOBMC)/THF和进一步与Lewis酸AlCl3反应制得的(RSMgCl)n-AlCl3/THF(n=1,1.5,2)苯硫酚盐基溶液用作可充镁电池电解液,采用循环伏安和恒电流充放电测试研究了电解液的镁沉积-溶出性能和氧化分解电位.结果表明,苯硫酚上的基团种类和RSMgCl与AlCl3的比例对其电化学性能有影响.其中,0.5 mol·L-1(IPBMC)1.5-AlCl3/THF溶液具有最佳的电化学性能,其氧化分解电位适宜(2.4 V(vs Mg/Mg2+)),镁沉积-溶出循环效率稳定,过电位低,电导率较高(2.48 mS·cm-1),与正极材料Mo6S8兼容性良好,且具有一定的空气稳定性,配制方便,有希望应用于实际的可充镁电池体系中.

The benzenethiolate-based solutions （RSMgCI）n-AlCl3/tetrahydrofuran （THF） （R=4-methylbenzene, 4-isopropylbenzene, 4-methoxybenzene; n=1, 1.5, 2, respectively） were obtained by the simple reaction of benzenethiol compounds with the Grignard reagent C2HsMgCI/THF and AlCl3 in THF, and the electrochemical performance as the rechargeable magnesium battery electrolytes are reported. First, 4-methyl-benzenethiolate magnesium chloride （MBMC）/THF, 4-isopropylbenzenethiolate magnesium chloride （IPBMC）/THF, and 4- methoxybenzenethiolate magnesium chloride （MOBMC）/THF solutions （termed as RSMgCI/THF） were synthesized by the reaction of 4-methylbenzenethiol, 4-isopropylbenzenethiol, and 4-methoxybenzenethiol compounds, respectively, with C2HsMgCI/THF via a hydrogen metal-radical exchange with rapid evolution of ethane gas. Furthermore, （RSMgCI）n-AlCl3/THF solutions were obtained by the reaction of RSMgCI/THF with AlCl3/THF at different molar ratios of RSMgCI：AlCl3. The benzenethiolate-based solutions as electrolytes for rechargeable magnesium batteries were characterized in term of anodic stability and reversibility of magnesium deposition-dissolution using cyclic voltammetry and galvanostatic charge/discharge techniques. Furthermore, the compatibility of the solutions with Mo6S8 cathode material was verified using coin cells with a Mo6S8 cathode, Mg anode, and benzenethiolate-based electrolyte. It is concluded that both the substituents on benzenethiol and the ratio of RSMgCI：AlCl3 have an effect on the electrochemical performance. 0.5 mol· L^-1 （IPBMC）1.5-AlCl3/THF shows the best electrochemical performance with 2.4 V （vs Mg/Mg^2＋） anodic stability, a low voltage for magnesium deposition-dissolution, a high cycling reversibility, and good compatibility with the Mo6S8 cathode. Moreover, the air insensitive character and easy preparation make it a promising candidate for rechargeable battery electrolytes.