Affiliation:
1. Faculty of Engineering and Physical Sciences University of Southampton Southampton SO17 1BJ UK
2. Department of Chemical Engineering The City College of New York CUNY New York 10031 USA
3. Centre for Electronics Frontiers School of Engineering University of Edinburgh Edinburgh EH9 3JL UK
4. Chemical and Biomolecular Engineering University of Illinois at Urbana‐Champaign Urbana IL 61801 USA
Abstract
AbstractChloroaluminate ionic liquids are commonly used electrolytes in rechargeable aluminum batteries due to their ability to reversibly electrodeposit aluminum at room temperature. Progress in aluminum batteries is currently hindered by the limited electrochemical stability, corrosivity, and moisture sensitivity of these ionic liquids. Here, a solid polymer electrolyte based on 1‐ethyl‐3‐methylimidazolium chloride‐aluminum chloride, polyethylene oxide, and fumed silica is developed, exhibiting increased electrochemical stability over the ionic liquid while maintaining a high ionic conductivity of ≈13 mS cm−1. In aluminum–graphite cells, the solid polymer electrolytes enable charging to 2.8 V, achieving a maximum specific capacity of 194 mA h g−1 at 66 mA g−1. Long‐term cycling at 2.7 V showed a reversible capacity of 123 mA h g−1 at 360 mA g−1 and 98.4% coulombic efficiency after 1000 cycles. Solid‐state nuclear magnetic resonance spectroscopy measurements reveal the formation of five‐coordinate aluminum species that crosslink the polymer network to enable a high ionic liquid loading in the solid electrolyte. This study provides new insights into the molecular‐level design and understanding of polymer electrolytes for high‐capacity aluminum batteries with extended potential limits.
Funder
National Science Foundation
National Aeronautics and Space Administration
Lloyd's Register Foundation
Subject
General Materials Science,Renewable Energy, Sustainability and the Environment