Nonaqueous Lithium Battery Electrolyte for Stable High-Temperature Storage
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Solution Overview
Problem
Lithium secondary batteries experience a decrease in capacity and an increase in internal resistance when stored in high-temperature environments for extended periods, which existing nonaqueous electrolyte solutions fail to adequately address.
Innovation Solution
A nonaqueous electrolyte solution containing specific compounds such as nitrogen-containing lithium salts, cyclic sulfur-containing esters, cyclic dicarbonyl compounds, and cyclic carbonates, which form stable solid electrolyte interphase films to inhibit side reactions and maintain battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolyte solutions are used, then the battery can operate normally, but the capacity decreases and internal resistance increases when stored in high-temperature environments for extended periods
Solution Approach 1:
The electrolyte solution is pre-formulated with a specific combination of additives (compounds of formula (1), (2), and (3)) that proactively form stable protective films on the electrodes during initial cycles. This preliminary action prevents subsequent degradation during high-temperature storage, addressing the contradiction by preparing the battery system in advance to resist future thermal stress.
Solution Approach 2:
The invention uses a composite electrolyte system combining multiple additives with specific functional properties: compound (1) for SEI formation, compound (2) for CEI formation, and compound (3) for supplemental stability. This composite approach creates synergistic effects that maintain battery performance during extended high-temperature storage, resolving the contradiction between normal operation and thermal stability.
2Temperature
If existing electrolyte additives are used, then some high-temperature performance is achieved, but capacity retention deteriorates after 14 days or longer of high-temperature storage
Solution Approach 1:
The invention optimizes the concentration parameters of three key additives within specific ranges: compound (1) at 0.01-5% by mass, compound (2) at 0.01-5% by mass, and compound (3) at 0.01-10% by mass. These parameter changes create the optimal balance for forming stable interphase films that resist degradation during extended high-temperature storage, addressing both temperature resistance and duration requirements.
Solution Approach 2:
The electrolyte additives act as intermediary substances that mediate between the electrodes and the electrolyte solution. Compounds (1), (2), and (3) form intermediate protective layers (SEI and CEI films) that prevent direct harmful interactions between the electrolyte and electrodes during high-temperature storage, enabling both temperature resistance and extended duration stability.
3Ease of manufacture
If simple electrolyte formulations are used, then manufacturing is easier, but the battery cannot maintain performance after prolonged high-temperature storage
Solution Approach 1:
The electrolyte formulation is segmented into three distinct functional components: compound (1) for anode protection, compound (2) for cathode protection, and compound (3) for supplemental stability. This segmentation allows each component to perform its specific function optimally while maintaining overall manufacturing simplicity, as each additive can be independently sourced and mixed in defined concentrations.
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 inhibits the decrease in capacity and increase in internal resistance of lithium secondary batteries even after prolonged high-temperature storage, ensuring sustained battery performance.
Implementation Method 1
a nonaqueous electrolyte solution containing: a compound (I) represented by the following Formula (I); and a compound (II) represented by the following Formula (II)... which form stable solid electrolyte interphase films to inhibit side reactions
Implementation Method 2
The nonaqueous electrolyte solution is composed of an organic solvent and a solute... contain a compound (I)... and a compound (II)... form stable solid electrolyte interphase films
Data Source
AI summary
Provided is a nonaqueous electrolyte solution for a lithium secondary battery, the nonaqueous electrolyte solution containing a compound (I) represented by Formula (I) and a compound (II) represented by Formula (II). In Formula (I), each of R1 and R2 independently represents a substituent such as an alkyl group having from 1 to 7 carbon atoms. In Formula (II), R3 represents an oxygen atom or the like; R4 represents a group represented by Formula (ii-1), a group represented by Formula (ii-2), or the like; and * represents a binding position. In Formula (ii-1), R41 represents an oxymethylene group or the like and, in Formula (ii-2), R42 represents an alkyl group having from 1 to 6 carbon atoms, or the like.