Cyclic Sulfate Electrolyte for High-Temperature Lithium Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face stability issues at high temperatures due to structural instability of lithium-metal oxide cathodes and side reactions with conventional organic solvents, leading to overheating and potential explosions, while existing ionic liquid electrolytes can deteriorate battery performance.
Innovation Solution
A non-aqueous electrolyte solution comprising an amide compound, an ionizable lithium salt, and a cyclic sulfate, which forms a stable solid electrolyte interface (SEI) layer, enhancing thermal and chemical stability and preventing swelling, is developed. The solution includes specific amide compounds like N-methoxyethyl methylcarbamate and cyclic sulfates like 1,3-propanediol cyclic sulfate, optimizing the mole ratio and concentration to achieve sufficient ionic conductivity and high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic solvents (ethylene carbonate, propylene carbonate, etc.) are used in the electrolyte, then the battery can achieve sufficient ionic conductivity, but the solvents cause swelling and side reactions at high temperature, deteriorating battery stability
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific cyclic sulfate compound with particular molecular structure (formula 1) and controlling its concentration (0.01-10 parts by weight per 100 parts electrolyte solution). This parameter change transforms the electrolyte's high-temperature behavior, preventing swelling and side reactions while maintaining stability.
Solution Approach 2:
The cyclic sulfate compound acts as an intermediary substance that mediates between the electrode and the bulk electrolyte. It forms a protective interface layer that prevents direct harmful interactions between conventional organic solvents and the electrode at high temperature, while still allowing necessary ionic transport.
2Quantity of substance
If the charge potential is raised to increase capacity, then the capacity of lithium-metal oxide increases, but the lithium-metal oxide becomes structurally unstable, causing oxygen generation and overheating
Solution Approach 1:
The cyclic sulfate compound provides beforehand cushioning by forming a protective interface layer on the electrode surface before structural degradation can occur. This pre-formed protective layer cushions against the destabilizing effects of high charge potential, preventing oxygen generation and maintaining structural stability even at elevated capacities.
3Reliability
If ionic liquid with imidazolium and ammonium cations is used as electrolyte, then thermal stability is improved, but the cations may be reduced at high voltage or intercalated with lithium ions in anode, deteriorating battery performances
Solution Approach 1:
Instead of using expensive ionic liquids that cause performance deterioration, the patent employs a small amount of cyclic sulfate compound (0.01-10 parts by weight per 100 parts electrolyte) as a sacrificial additive. This disposable-like approach uses a minimal concentration of the additive to achieve the desired thermal stability without the harmful effects of bulk ionic liquid usage.
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 provides improved thermal and chemical stability, maintaining high discharge capacity and preventing swelling at high temperatures, thereby enhancing the safety and performance of lithium secondary batteries.
Implementation Method 1
the electrolyte used in a lithium secondary battery forms a kind of a solid electrolyte interface (SEI) layer on the surface of an anode by reaction with carbon composing the anode during initial charging
Implementation Method 2
The SEI layer formed functions as an ion tunnel to prevent the organic solvent from being inserted in the anode structure and allow only lithium ions to selectively pass through
Implementation Method 3
the non-aqueous electrolyte solution has high thermal and chemical stability, thereby improving the stability of a battery at room temperature and a high temperature
Implementation Method 4
the non-aqueous electrolyte solution has high thermal and chemical stability, thereby improving the stability of a battery at room temperature and a high temperature
Implementation Method 5
optimizing the mole ratio and concentration to achieve sufficient ionic conductivity and high-temperature stability
Data Source
Figure 1
AI summary
The present disclosure provides a non-aqueous electrolyte solution for a lithium secondary battery, comprising an amide compound having a specific structure; an ionizable lithium salt; a cyclic sulfate; and an organic solvent, and a lithium secondary battery comprising the non-aqueous electrolyte solution. The non-aqueous electrolyte solution of the present disclosure has good thermal and chemical stability and can be effectively used as the electrolyte of a lithium secondary battery to provide good charge/discharge performances and stability at a high temperature.