Non-aqueous Electrolyte for Broad Temperature Battery Performance
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Solution Overview
Problem
Existing nonaqueous electrolytic solutions fail to adequately improve electrochemical characteristics in a broad temperature range, particularly low-temperature discharge properties after high-temperature storage in energy storage devices like lithium batteries.
Innovation Solution
A nonaqueous electrolytic solution comprising a solvent with two or more kinds of cyclic carbonates and a cyclic acid anhydride with a side chain having 3 or more carbon atoms and a double or triple bond at the end, which forms a surface film with improved heat resistance and lithium ion permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolytic solutions are used, then the battery can operate, but the electrochemical characteristics deteriorate in a broad temperature range especially at low temperatures after high-temperature storage
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolytic solution by incorporating specific cyclic carbonate esters (vinylene carbonate at 0.01-5% by mass and fluoroethylene carbonate at 0.01-5% by mass) alongside conventional cyclic carbonates. This parameter change in composition enables the formation of a surface film with optimized properties that maintains electrochemical characteristics across broad temperature ranges.
Solution Approach 2:
The patent creates a composite electrolytic solution system combining multiple cyclic carbonate esters with different chemical structures and properties. The synergistic combination of vinylene carbonate, fluoroethylene carbonate, and conventional cyclic carbonates (EC, PC, DEC, EMC, DM) produces a surface film with balanced heat resistance and low-temperature ionic conductivity, resolving the temperature-range performance issue.
2Stability of the object's composition
If the surface film on the negative electrode becomes denser to improve heat resistance, then high-temperature stability improves, but low-temperature lithium ion permeability deteriorates
Solution Approach 1:
The patent achieves different local qualities within the surface film structure by using cyclic carbonate esters with different functional groups. The vinylene carbonate component contributes to heat resistance while the fluoroethylene carbonate component enhances ionic conductivity, creating a multi-layered or gradient film structure that simultaneously provides both properties.
Solution Approach 2:
By carefully controlling the mass percentages of vinylene carbonate (0.01-5%) and fluoroethylene carbonate (0.01-5%) in the electrolytic solution, the patent optimizes the surface film parameters to achieve the right balance between density for heat resistance and porosity for ionic conductivity, preventing the trade-off from occurring.
3Reliability
If cyclic carbonate esters are added to improve surface film formation, then electrochemical characteristics improve, but the complexity of electrolyte composition increases
Solution Approach 1:
The patent selects cyclic carbonate esters that serve multiple functions simultaneously: vinylene carbonate provides both surface film formation and heat resistance enhancement, while fluoroethylene carbonate contributes to ionic conductivity and film stability. This multi-functionality reduces the need for additional separate additives, managing composition complexity.
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 significantly enhances electrochemical characteristics in a broad temperature range by preventing excessive surface film densification, thereby maintaining battery performance and capacity retention.
Implementation Method 1
a decomposed product and gas generated through reductive decomposition of the solvent in the nonaqueous electrolytic solution on the surface of the negative electrode during charging
Implementation Method 2
the nonaqueous solvent in the nonaqueous electrolytic solution locally undergoes partial oxidative decomposition at the interface between the positive electrode material and the nonaqueous electrolytic solution in a charged state
Implementation Method 3
a nonaqueous electrolytic solution comprising a nonaqueous solvent having dissolved therein an electrolyte salt
Data Source
AI summary
A nonaqueous electrolytic solution that is capable of improving the electrochemical characteristics in a broad temperature range, and an energy storage device using the same are provided, and the nonaqueous electrolytic solution contains a nonaqueous solvent having dissolved therein an electrolyte salt, in which the nonaqueous solvent contains two or more kinds of cyclic carbonates selected from ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, trans-or cis-4,5-difluoro-1,3-dioxolan-2-one, vinylene carbonate, vinyl ethylene carbonate and 4-ethynyl-1,3-dioxolan-2-one, and the nonaqueous electrolytic solution further contains a cyclic acid anhydride represented by the following general formula (I) having bonded thereto a side chain that has 3 or more carbon atoms and has a double bond or a triple bond at an end thereof in an amount of from 0.01 to 10% by mass: wherein R1 and R2 each independently represent a hydrogen atom, a halogen atom or an alkyl group having from 1 to 6 carbon atoms, at least one hydrogen atom of which may be substituted by a halogen atom; and R3 represents a linear or branched alkenyl group having from 2 to 4 carbon atoms and having a double bond at an end thereof or a linear or branched alkynyl group having from 2 to 4 carbon atoms and having a triple bond at an end thereof.