Date Published: December 12, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Yan Xu, Guangmin Zhou, Shuyang Zhao, Wanfei Li, Feifei Shi, Jia Li, Jun Feng, Yuxing Zhao, Yang Wu, Jinghua Guo, Yi Cui, Yuegang Zhang.
Rechargeable magnesium/sulfur (Mg/S) batteries are widely regarded as one of the alternatives to lithium‐ion batteries. However, a key factor restricting their application is the lack of suitable electrolyte. Herein, an electrolyte additive that can reduce the polarization voltage is developed and 98.7% coulombic efficiency is realized. The as‐prepared Mg‐ion electrolyte exhibits excellent Mg plating/stripping performance with a low overpotential of 0.11 V for plating process, and high anodic stability up to 3.0 V (vs Mg/Mg2+). When it is coupled with magnesium polysulfide, which has high reactivity and is homogeneously distributed on carbon matrix, the Mg/S cells deliver a good cycling stability with a high discharge capacity over 1000 mAh g−1 for more than 50 cycles.
Material Preparation: Anhydrous magnesium chloride (MgCl2, 99.9%), aluminum chloride (AlCl3, 99.99%), and anhydrous DG were received from Sigma‐Aldrich, PYR14TFSI was purchased from MTI Corporation, and YCl3 was prepared by Prof. Y. M. Yao in Soochow University. All reactants and solvents, unless otherwise stated, were used as received. All the samples were handled in an argon‐filled glovebox with water below 0.5 ppm and oxygen below 15 ppm. MgCl2 (19 mg) and anhydrous YCl3 (78 mg) (or MgCl2 (19 mg) and anhydrous AlCl3 (53.3 mg)) were added to a 10 mL glass vial, which was then vigorously stirred at 120 °C in 1.5 mL PYR14TFSI overnight. Then 1.5 mL DG was added with stirring overnight at room temperature to form the Y‐based electrolyte. Treatment of 16.7 mg of Mg (0.688 mmol), 180 mg of sulfur (0.702 mmol), and 3 mL of N‐MeIm at 95 °C for 12 h to obtain a red solution. Then 360 mg G‐CNT was added and stirred overnight. 60 mg polyvinylidene fluoride (PVDF) dissolved in NMP was added to the above slurry. The resulting slurry was uniformly spread via a doctor blade on pyrolytic graphite. G‐CNT was pasted on pyrolytic graphite first and then MgPS solution was dropped onto G‐CNT. Then the electrode was dried at 60 °C in the glovebox. Typically, each electrode contains about 0.7–1.0 mg cm−2 of the active material.
The authors declare no conflict of interest.