An Aluminum–Sulfur Battery with a Fast Kinetic Response

• Published in: Angewandte Chemie International Edition 2018-02, Vol.57 (7), p.1898-1902
• Main Authors: Yang, Huicong, Yin, Lichang, Liang, Ji, Sun, Zhenhua, Wang, Yuzuo, Li, Hucheng, He, Kuang, Ma, Lipo, Peng, Zhangquan, Qiu, Siyao, Sun, Chenghua, Cheng, Hui‐Ming, Li, Feng
• Format: Article
• Language: English
• Subjects: Aluminum; aluminum–sulfur battery; Batteries; Charge density; Current density; Density functional theory; Electrochemical analysis; Electrochemistry; energy storage; ionic liquid electrolytes; Kinetics; Sulfur; Sulfur content
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201711328

The electrochemical performance of the aluminum‐sulfur (Al‐S) battery has very poor reversibility and a low charge/discharge current density owing to slow kinetic processes determined by an inevitable dissociation reaction from Al2Cl7− to free Al3+. Al2Cl6Br− was used instead of Al2Cl7− as the dissociation reaction reagent. A 15‐fold faster reaction rate of Al2Cl6Br− dissociation than that of Al2Cl7− was confirmed by density function theory calculations and the Arrhenius equation. This accelerated dissociation reaction was experimentally verified by the increase of exchange current density during Al electro‐deposition. Using Al2Cl6Br− instead of Al2Cl7−, a kinetically accelerated Al‐S battery has a sulfur utilization of more than 80 %, with at least four times the sulfur content and five times the current density than that of previous work. A major hindrance of Al‐S batteries is slow kinetics, leading to a low charge/discharge current density and low sulfur content. The relationship between the electrochemical kinetics and the electrolyte was explored, focusing on accelerating the rate‐determining step (dissociation of Al2X7− anions in ionic‐liquid electrolyte). Using Al2Cl6Br− instead of Al2Cl7− led to faster dissociation and an improvement of electrochemical performance.