Non-Aqueous Electrolyte Composition for High-Temperature Capacity Retention
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Solution Overview
Problem
Lithium-ion secondary batteries using existing non-aqueous electrolyte solutions experience a decrease in capacity and an increase in direct current resistance when charged or discharged in high temperature environments.
Innovation Solution
A non-aqueous electrolyte solution containing specific chain and cyclic sulfone compounds, cyclic carbonate compounds, sulfonimide lithium salt compounds, cyclic dicarbonyl compounds, and lithium fluorophosphate, along with a non-aqueous solvent system, is used to form stable solid electrolyte interface films that inhibit decomposition and maintain performance in high temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional non-aqueous electrolyte solution is used, then the battery can operate at high temperature, but the capacity decreases and direct current resistance increases during charging and discharging
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific chain sulfone compounds (Formula I) and cyclic sulfone compounds (Formula II) with defined structural parameters (R11, R12, R21, R22, R23 groups). These parameter changes in molecular structure lead to improved SEI film stability at high temperatures, resolving the contradiction between high temperature operation and capacity retention.
Solution Approach 2:
The patent creates a composite electrolyte system combining multiple components: chain sulfone compound (I), cyclic sulfone compound (II), and other auxiliary compounds. This composite material approach synergistically improves the electrolyte's ability to form stable SEI films at high temperatures while maintaining low resistance and high capacity, addressing both aspects of the reliability issue.
2Temperature
If the battery is stored in a high temperature environment for a long period, then thermal energy is maintained, but capacity loss increases and performance deteriorates
Solution Approach 1:
The patent employs preliminary action by having the chain sulfone compound (I) and cyclic sulfone compound (II) pre-form stable solid electrolyte interface (SEI) films on the electrode surfaces before high-temperature storage begins. These pre-formed SEI films act as protective barriers that prevent further decomposition reactions during prolonged high-temperature storage, thereby maintaining capacity and reducing performance deterioration.
Solution Approach 2:
The electrolyte composition provides beforehand cushioning against high-temperature degradation by forming chemically stable SEI films that cushion and protect the electrode materials from harmful thermal reactions. This protective layer absorbs and mitigates the damaging effects of high-temperature storage, enabling longer storage duration without significant capacity loss.
3Ease of manufacture
If existing electrolyte composition is used, then manufacturing is simple, but direct current resistance increases during high temperature charging and discharging
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration ratios and molecular structures of the sulfone compounds in the electrolyte. By carefully adjusting these compositional parameters, the invention achieves low direct current resistance at high temperatures while maintaining a relatively simple manufacturing process that involves standard electrolyte preparation techniques.
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 effectively reduces capacity loss and resistance increase in lithium-ion batteries stored in high temperature environments by forming stable SEI films, enhancing battery performance and durability.
Implementation Method 1
forming stable solid electrolyte interface films that inhibit decomposition and maintain performance in high temperature conditions
Implementation Method 2
Lithium-ion secondary batteries are drawing attention as batteries having a high energy density
Data Source
AI summary
A non-aqueous electrolyte solution contains a chain sulfone compound (I) represented by Formula (I) and a cyclic sulfone compound (II) represented by Formula (II). The content of the chain sulfone compound (I) is from 0.01% by mass to 10% by mass with respect to the total amount of the non-aqueous electrolyte solution. In Formula (I), each of R11 and R12 independently represents an alkyl group, or a fluorinated alkyl group. In Formula (II), R21 represents an alkylene group, an alkenylene group, or a group represented by Formula (ii-1); and * represents a binding site; in which in Formula (ii-1), R22 represents a hydrogen atom, an alkyl group, or a group represented by Formula (ii-2); and R23 represents an alkyl group, or a group represented by Formula (ii-2).