Lithium Battery Electrolyte Composition for Stable High-Energy Cycling
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Solution Overview
Problem
Lithium secondary batteries face issues with electrolyte solution decomposition during charge/discharge cycles, leading to reduced capacity and cycle characteristics due to high reactivity between battery components, resulting in electrolyte shortage and decreased energy density.
Innovation Solution
An electrolyte solution comprising a cyclic compound represented by Formula (1) or Formula (2), a hydrofluoroether, and an ether without fluorine, which improves charge/discharge efficiency, oxidation-reduction reaction reversibility, and solubility of lithium salts, enhancing energy density and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional electrolyte solutions are used in lithium secondary batteries, then high energy density can be achieved, but the cycle characteristics are deteriorated due to high reactivity between battery components and electrolyte solution
Solution Approach 1:
The patent introduces a specific cyclic compound (Formula 1 or 2) as an intermediary substance in the electrolyte solution that mediates between the high reactivity requirement for energy density and the stability requirement for cycle characteristics. This compound forms a protective interface layer that prevents direct harmful reactions between electrolyte and battery components while maintaining ionic conductivity for high energy density.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte solution by specifying precise proportions of cyclic compound (5-50 vol%), linear chain compound (10-60 vol%), and cyclic ether compound (5-40 vol%). This parameter optimization resolves the contradiction by achieving the right balance between reactivity (for energy density) and stability (for cycle characteristics).
2Productivity
If repeated charge/discharge are performed to achieve high productivity, then battery capacity decreases due to irreversible decomposition reaction of electrolyte solution
Solution Approach 1:
The patent applies preliminary action by having the cyclic compound (Formula 1 or 2) react first during initial cycles to form a stable solid electrolyte interfacial (SEI) layer on the electrode surfaces. This preliminary reaction prevents subsequent irreversible decomposition of the bulk electrolyte solution during repeated charge/discharge cycles, thereby maintaining productivity while minimizing substance loss.
Solution Approach 2:
The patent converts the potentially harmful irreversible decomposition reaction into a beneficial process by designing the cyclic compound to undergo controlled initial decomposition that forms a protective SEI layer. This layer then prevents further harmful decomposition, transforming the initial substance consumption into a long-term protective mechanism that enables sustained high productivity.
3Use of energy by moving object
If high voltage is used to improve energy density, then reactivity between battery members and electrolyte solution increases causing safety issues
Solution Approach 1:
The cyclic compound (Formula 1 or 2) acts as an intermediary protective layer between the high-voltage battery components and the electrolyte solution. This mediator enables high voltage operation for improved energy density while preventing direct harmful reactions that would compromise safety, by forming a stable interface that withstands high voltage stress.
Solution Approach 2:
The patent creates a composite electrolyte system combining cyclic compound (Formula 1 or 2), linear chain compound, and cyclic ether compound in specific ratios. This composite material approach provides both the high voltage stability needed for energy density and the chemical resistance required for safety, resolving the contradiction between performance and harm reduction.
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 proposed electrolyte solution configuration significantly improves the energy density and cycle stability of lithium secondary batteries by suppressing irreversible decomposition and forming a suitable solid electrolyte interfacial layer, maintaining high performance over repeated cycles.
Implementation Method 1
forming a suitable solid electrolyte interfacial layer, maintaining high performance over repeated cycles
Implementation Method 2
an ether not having a fluorine atom as the solvent, which improves charge/discharge efficiency, oxidation-reduction reaction reversibility, and solubility of lithium salts
Implementation Method 3
a lithium secondary battery in which charge/discharge are performed by transferring lithium ions between a positive electrode and a negative electrode
Implementation Method 4
improves charge/discharge efficiency, oxidation-reduction reaction reversibility
Data Source
AI summary
The present invention provides an electrolyte solution for a lithium secondary battery, which can achieve both a high energy density and excellent cycle characteristics. The present invention relates to an electrolyte solution for a lithium secondary battery, the electrolyte solution including a cyclic compound represented by Formula (1) or Formula (2), a hydrofluoroether, an ether not having a fluorine atom, and a lithium salt.