Non-aqueous electrolyte solution and power storage device using same
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Solution Overview
Problem
Existing lithium secondary batteries suffer from worsened electrochemical characteristics in wide temperature ranges due to solvent decomposition and gas generation, which affects discharge capacity and cycle properties, particularly under high-temperature conditions.
Innovation Solution
A nonaqueous electrolytic solution containing a specific phosphonate compound with alkenyl or alkynyl groups, combined with lithium salts and solvents, is used to enhance discharge capacity retention and prevent gas generation in energy storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (ammonium fluorosulfonate mixed with lithium hydroxide aqueous solution) are used to produce lithium fluorosulfonate, then lithium fluorosulfonate can be obtained, but the production process becomes complex and contamination with ammonia occurs
Solution Approach 1:
The invention extracts and eliminates the problematic intermediate step involving ammonium fluorosulfonate and cation exchange. Instead of using the conventional two-step process (forming ammonium salt then exchanging cations), the patent directly synthesizes lithium fluorosulfonate by reacting fluorosulfonic acid with lithium salt in non-aqueous solvent, removing the source of ammonia contamination and process complexity
Solution Approach 2:
The invention introduces a non-aqueous solvent as an intermediary medium to enable direct reaction between fluorosulfonic acid and lithium salt. This intermediary allows the reaction to proceed without forming the problematic ammonium intermediate, achieving both simplification and high purity
2Productivity
If LiClO4 is used as electrolyte, then electrolyte can be provided, but active oxygen is formed due to decomposition at electropositive potential which attacks the solvent and accelerates decomposition
Solution Approach 1:
The invention changes the chemical composition parameter of the electrolyte from LiClO4 to lithium fluorosulfonate (LiFSO3). This parameter change fundamentally alters the decomposition behavior at electropositive potentials, preventing the formation of active oxygen while maintaining high discharge capacity and improving battery performance
3Productivity
If CF3SO3Li, LiBF4 or LiPF6 are used as electrolyte, then electrolyte can be provided, but fluorine is formed due to decomposition at electropositive potential which attacks the solvent and accelerates decomposition
Solution Approach 1:
The invention changes the electrolyte composition from fluorine-containing salts (CF3SO3Li, LiBF4, LiPF6) to lithium fluorosulfonate. Although lithium fluorosulfonate contains fluorine in its structure, the fluorine is bonded in a stable configuration that prevents decomposition and release of free fluorine at electropositive potentials, thereby eliminating solvent attack while maintaining high productivity
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 improves discharge capacity retention and prevents gas generation in energy storage devices, even under high-temperature conditions, by promoting polymerization and forming a strong, heat-resistant surface film that inhibits solvent decomposition.
Implementation Method 1
A method involving the reaction of fluorosulfonic acid with a specific lithium salt in a non-aqueous solvent to produce high-purity lithium fluorosulfonate
Implementation Method 2
non-aqueous electrolytic solution containing lithium fluorosulfonate
Data Source
AI summary
There is provided a nonaqueous electrolytic solution for an energy storage device which is a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent and contains a phosphonate represented by the following general formula (I), and an energy storage device using the same: wherein, R1 represents an alkenyl group having 2 to 6 carbon atoms or an alkynyl group having 3 to 6 carbon atoms, and R2 and R3 each independently represent an alkynyl group having 3 to 6 carbon atoms.