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A Sustainable Redox-Flow Battery with an Aluminum-Based, Deep-Eutectic-Solvent Anolyte
Changkun Zhang1,2, Yu Ding1, Leyuan Zhang1
1Materials Science and Engineering Program and Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
Angewandte Chemie (International Ed. in English)
|May 12, 2017
Summary
Aluminum-based deep-eutectic solvents offer a promising solution for non-aqueous redox-flow batteries, overcoming limitations in anolyte development for grid storage. This research demonstrates high energy density and potential for cost-effective, sustainable energy storage systems.
Area of Science:
- Materials Science
- Electrochemistry
- Energy Storage
Background:
- Nonaqueous redox-flow batteries (RFBs) face challenges in anolyte development, specifically low solubility and inadequate redox potentials of redox species.
- The advancement of catholytes has significantly outpaced that of anolytes, hindering the overall performance and scalability of RFB technology.
Purpose of the Study:
- To investigate an aluminum-based deep-eutectic solvent (DES) as a high-performance anolyte for non-aqueous redox-flow batteries.
- To address the limitations of solubility and redox potential in traditional anolyte materials.
- To evaluate the electrochemical performance and energy density of a RFB utilizing the novel aluminum-based DES anolyte.
Main Methods:
- Synthesis and characterization of an aluminum-based deep-eutectic solvent.
- Electrochemical measurements including cyclic voltammetry and galvanostatic cycling to assess redox behavior and capacity.
- Assembly and testing of a prototype redox-flow battery cell using the developed anolyte coupled with different catholytes (I3-/I- and Br2-based).
Main Results:
- The aluminum-based DES achieved a high anolyte concentration of approximately 3.2 M and a low redox potential of 2.25 V vs. Li+/Li.
- Electrochemical tests yielded a reversible volumetric capacity of 145 Ah L-1 and energy densities of 189 Wh L-1 (165 Wh kg-1) with an I3-/I- catholyte.
- Coupling with a Br2-based catholyte resulted in a higher cell voltage and a theoretical energy density exceeding 200 Wh L-1.
Conclusions:
- Aluminum-based DES anolytes demonstrate significant potential for enhancing the performance of non-aqueous redox-flow batteries.
- The use of abundant, dendrite-free aluminum anodes and environmentally benign DES offers a pathway towards cost-effective and sustainable grid-scale energy storage.
- This work paves the way for next-generation RFBs with improved energy density and long-term stability.
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