Fluorinated Electrolyte Composition for High-Temperature Li-Ion Storage
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Solution Overview
Problem
Conventional electrolyte solutions for lithium-ion secondary batteries deteriorate during storage, leading to a decrease in residual capacity and an increase in resistance, especially at high temperatures.
Innovation Solution
An electrolyte solution comprising 24.9-75 mass% of a compound of the formula R11<CFX11<(CH2)n11COOR12<, 0.1-3 mass% of a specific additive, and 24.9-75 mass% of a fluorinated carbonate, which helps in maintaining the stability of the electrolyte solution even after high-temperature storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used, then the battery can operate initially, but the residual capacity decreases and resistance increases during storage at high temperatures
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific fluorinated cyclic carbonate compound with unique molecular structure (containing fluorine atoms and cyclic carbonate groups) to improve high-temperature storage stability and prevent capacity degradation
Solution Approach 2:
The patent creates a composite electrolyte system by combining the fluorinated cyclic carbonate compound with other electrolyte components, forming a synergistic mixture that provides both initial battery performance and long-term storage stability at high temperatures
2Reliability
If conventional electrolyte solutions are used, then the battery can operate initially, but the resistance increases during storage at high temperatures
Solution Approach 1:
The patent modifies the electrolyte's chemical composition by incorporating fluorinated cyclic carbonate compounds that maintain stable resistance characteristics during high-temperature storage, preventing the harmful increase in electrical resistance
Solution Approach 2:
The fluorinated cyclic carbonate compound acts as an intermediary substance that stabilizes the interface between electrolyte and electrode, preventing degradation reactions that would otherwise increase resistance during storage
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 electrolyte solution effectively maintains the residual capacity and resistance of lithium-ion secondary batteries, preventing deterioration even after storage at high temperatures.
Implementation Method 1
a nonaqueous electrolyte solution for a secondary battery, containing a nonaqueous solvent that contains a lithium salt of an electrolyte, wherein the nonaqueous solvent contains a fluorinated acyclic carbonate of the following formula (1) and a film-forming compound that is to be decomposed within a range of +1.0 to 3.0 V with reference to the equilibrium potential between lithium metal and a lithium ion
Implementation Method 2
JP-A-2008-257988 discloses a nonaqueous electrolyte solution containing: a solvent (I) for dissolving an electrolyte salt that contains a fluorine-containing ester solvent (A) of the formula
Data Source
AI summary
The invention provides an electrolyte solution whose residual capacity is less likely to decrease and whose percentage increase in resistance is less likely to change even after stored at high temperature. The electrolyte solution contains a compound (1) represented by the following formula (1): R11CFX11(CH2)n11COOR12 wherein R11 is H, F, a C1-C3 non-fluorinated alkyl group, or a C1-C3 fluorinated alkyl group; X11 is H or F; R12 is a C1-C3 non-fluorinated alkyl group or a C1-C3 fluorinated alkyl group; and n11 is an integer of 0 to 3; a fluorinated carbonate; and a specific additive.