铝-硫电池用AlCl3/乙酰胺电解液改性研究

铝-硫电池是具有高能量密度和低成本优势的新型电化学储能体系。电解液是决定铝-硫电池性能的关键，已报道的咪唑类离子液体存在成本高等问题。申请人于2018年验证了AlCl3/乙酰胺共晶盐作为铝-硫电池电解液的可行性，实现了硫正极的高放电比容量（>1500mAh/g）和可循环性（60圈后比容量为500mAh/g），并阐明了电解液中络合离子存在形态。该电解液具有显著的低成本优势，但依然存在电化学窗口窄（≤1.8V vs.Al3+/Al）、电导率低（<10-3 Scm-1）等问题，制约铝-硫电池的进一步发展。本项目拟开展AlCl3/乙酰胺电解液的改性研究，通过电解液添加剂、阴离子替换及乙酰胺衍生基团取代来改善其物理化学性质，揭示改性方法对电解液结构与性质的影响规律和作用机制，进而解决铝-硫电池存在的循环稳定性差和动力学缓慢等问题。本项目将为开发高能量密度、低成本铝-硫电池提供理论和实验指导。

Aluminum-sulfur (Al-S) batteries are a new-type electrochemical energy storage system with noticeable advantages including high energy density and low cost. The electrolyte is the key factor determining the electrochemical performance of Al-S batteries, but the reported iminazole salt-based ionic liquid electrolytes suffer from severe drawbacks such as the high cost. In 2018, the applicant attempted and verified the feasibility of AlCl3/acetamide eutectic salt as a promising electrolyte for Al-S batteries, and realized a high discharge capacity of sulfur cathode (>1500mAh/g) and cyclability (500mAh/g after 60 cycles), and further identified the chemical structures of coordination ions. This electrolyte has significant low cost, but still suffer from problems including narrow electrochemical window (≤1.8V vs.Al3+/Al) and poor conductivity (<10-3 Scm-1), which significantly limit the further development of Al-S batteries. In this program, the applicant will systematically carry out the modification studies on the AlCl3/acetamide electrolyte, to optimize the physical/chemical properties of the electrolyte by electrolyte additives, anion displacement, and acetamide derivative group adjustment, to disclose the influencing principles and mechanisms of the modification methods on the structure and characteristics of electrolyte, and to solve the poor cyclability and slow reaction kinetics of Al-S batteries. This program will provide theoretical and practical guidance for the development of high-energy-density and long-cycle Al-S batteries.