Aqueous Lithium Ion Electrolyte with Phosphorus Oxoate
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Solution Overview
Problem
Aqueous liquid electrolytes for lithium ion secondary batteries have a limited electrochemically-stable potential range due to the influence of water, which restricts the performance of lithium ion secondary batteries.
Innovation Solution
A liquid electrolyte containing a lithium salt of a sulfonimide, such as lithium bis(trifluorosulfonyl)imide, and water, with the addition of specific phosphorus oxyacid ions like pyrophosphate, which increases the oxidation-side potential in the potential window, forming a high-quality solid electrolyte interface that enhances Li ion conductivity and expands the potential window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an aqueous liquid electrolyte is used in a lithium ion secondary battery, then the battery can operate with water-based electrolyte, but the electrochemically-stable potential range is limited due to water influence
Solution Approach 1:
Phosphorus oxoate acts as an intermediary substance added to the aqueous electrolyte containing lithium salt of sulfonimide. It mediates between water and the electrode surfaces, forming a protective interface layer that prevents water decomposition while maintaining ionic conductivity, thus expanding the potential window without removing water from the system.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by introducing phosphorus oxoate with specific molecular structure and properties. This parameter change modifies the electrochemical behavior of the aqueous electrolyte, raising the oxidation potential limit and expanding the stable potential range while maintaining water as the solvent.
2Power
If the potential window is expanded to increase voltage output, then higher energy density is achieved, but the electrolyte composition becomes more complex
Solution Approach 1:
Phosphorus oxoate serves multiple functions simultaneously: it expands the potential window, enhances Li ion conductivity, stabilizes the electrolyte composition, and protects electrode surfaces. This multi-functionality allows voltage output increase without proportionally increasing complexity, as a single additive achieves multiple objectives.
Solution Approach 2:
The electrolyte is formulated as a composite system combining water, lithium salt of sulfonimide, and phosphorus oxoate. This composite composition synergistically integrates multiple components where phosphorus oxoate enhances the properties of the base electrolyte mixture, achieving high voltage output while maintaining manageable composition complexity through functional complementarity.
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 solution results in a liquid electrolyte with an increased oxidation-side potential, allowing for a wider potential window and higher voltage output, enabling the use of previously unusable electrode materials and improving the performance of lithium ion secondary batteries.
Implementation Method 1
forming a high-quality solid electrolyte interface that enhances Li ion conductivity and expands the potential window
Implementation Method 2
the liquid electrolyte contains at least one kind of anion selected from the group consisting of an orthophosphoric ion, a pyrophosphate ion, an anion resulting from dissociation of phosphorous acid or a salt thereof, and an anion resulting from dissociation of phosphinic acid or a salt thereof
Data Source
AI summary
Provided is a liquid electrolyte for lithium ion batteries, which shows an increased oxidation-side potential in a potential window than ever before. A liquid electrolyte for lithium ion secondary batteries, the liquid electrolyte containing a lithium salt of a sulfonimide and water, wherein the liquid electrolyte contains at least one kind of anion selected from the group consisting of an orthophosphoric ion, a pyrophosphate ion, an anion resulting from dissociation of phosphorous acid or a salt thereof, and an anion resulting from dissociation of phosphinic acid or a salt thereof.