Aluminum Battery Electrolyte Composition for Stable SEI Formation
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Solution Overview
Problem
The high cost and corrosive nature of existing ionic liquid electrolytes limit the practical application of aluminum anodes in rechargeable batteries, as they fail to achieve high reversibility due to the formation of a passivating Al2O3 layer and slow interfacial ion transport.
Innovation Solution
Development of electrolyte compositions comprising ion-conducting salts and asymmetric ammonium salts, which form a stable solid electrolyte interphase (SEI) on the aluminum anode, enabling reversible plating and stripping of aluminum by adjusting the AlCl4− and Al2Cl7− ratios to maintain high coulombic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid electrolytes are used with aluminum anodes, then the aluminum surface is protected by a passivating Al2O3 layer, but reversible plating/stripping of aluminum is limited and coulombic efficiency is low
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using specific ionic liquids with defined ratios of AlCl4− and Al2Cl7− anions, along with imidazolium or ammonium cations. This compositional parameter change enables the electrolyte to effectively interact with and manage the Al2O3 passivation layer, achieving high reversibility (>90%) for aluminum plating and stripping reactions.
Solution Approach 2:
The patent employs composite ionic liquid electrolytes that combine multiple components: imidazolium or ammonium cations with AlCl4− and Al2Cl7− anions in specific ratios. This composite electrolyte system works synergistically to address both the passivation issue and enable reversible aluminum deposition, resolving the contradiction between protection and reactivity.
2Reliability
If imidazolium-based ionic liquid electrolytes are used to achieve aluminum reversibility, then high coulombic efficiency is obtained, but the cost and corrosive characteristics increase
Solution Approach 1:
The patent optimizes the compositional parameters of the ionic liquid electrolyte by adjusting the ratio of AlCl4− to Al2Cl7− anions and selecting specific cations (imidazolium or ammonium with particular alkyl groups). These parameter changes enable achieving high coulombic efficiency while reducing corrosiveness and cost compared to conventional electrolyte systems.
Solution Approach 2:
The patent introduces local quality variations by using asymmetric cations with specific alkyl group configurations (e.g., ethyl, propyl, butyl groups in particular positions). This local structural differentiation in the electrolyte molecules creates optimal interaction zones at the aluminum electrode interface, enhancing reversibility while controlling corrosivity and cost.
3Quantity of substance
If aluminum anodes are used to reduce cost and improve energy density, then earth abundance and volumetric energy density increase, but the passivating Al2O3 coating prevents effective electrochemical reactions
Solution Approach 1:
The patent introduces the ionic liquid electrolyte as an intermediary substance between the aluminum anode and the electrochemical reaction. This intermediary electrolyte system, with its specific AlCl4−/Al2Cl7− composition, mediates the interaction by managing the Al2O3 interface layer and enabling efficient charge transfer, thus reconciling the contradiction between aluminum's natural passivation and electrochemical reactivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The new electrolyte compositions achieve high coulombic efficiencies of over 99% for thousands of charge-discharge cycles, facilitating the use of aluminum anodes in cost-effective, long-duration energy storage batteries.
Implementation Method 1
enabling reversible plating and stripping of aluminum by adjusting the AlCl4− and Al2Cl7− ratios to maintain high coulombic efficiency
Implementation Method 2
reversible plating and stripping of aluminum by adjusting the AlCl4− and Al2Cl7− ratios to maintain high coulombic efficiency
Data Source
AI summary
Electrolyte compositions comprising one or more ion conducting salt(s) and one or more ammonium salt(s), such as, for example, asymmetric ammonium salt(s) or the like, which may, independently, be a quaternary ammonium salt. In various examples, the ammonium salt(s) independently comprise cations(s) chosen from primary ammonium cations, secondary ammonium cations, tertiary ammonium cations, quaternary ammonium cations, and the like, and any combination thereof. In various examples, an electrolyte composition further comprises one or more additional salt(s), which may, independently, be an ion-conducting salt. In various examples, an anode comprising an SEI layer is formed by contacting an anode, such as, for example, a metal anode or the like, with one or more electrolyte composition(s). In various examples, an electrochemical device, such as, for example, a battery, a supercapacitor, a fuel cell, an electrolyzer, an electrolytic cell, or the like comprises one or more composition(s) and/or one or more anode(s).