Spiro-Compound Li-Ion Electrolyte for Stable High-Temperature Cycling
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Solution Overview
Problem
Lithium-ion batteries face challenges in high-temperature storage and cycle performance, with existing additives leading to gas expansion and poor stability of the solid electrolyte interface (SEI) film, resulting in decreased reversible capacity and increased resistance over cycles.
Innovation Solution
A non-aqueous electrolyte comprising a spiro compound with specific structural features, along with 1,3-propane sultone and other additives, forms a dense and stable passivation film on the positive electrode, inhibiting solvent decomposition and improving high-temperature cycle and storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vinylene carbonate is added to the electrolyte to form a passive film on the negative electrode, then the cycle performance is improved, but the battery produces gas during high-temperature storage leading to swelling
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance that mediates between the negative electrode and the electrolyte. This compound优先 reacts to form a stable SEI film containing fluorinated species, which acts as a protective barrier that prevents both electrolyte decomposition and gas generation, while still allowing lithium ion transport
Solution Approach 2:
The patent modifies the chemical composition parameters of the SEI film by introducing fluorinated cyclic carbonate compounds with specific molecular structures (containing F, O, and C atoms in cyclic configurations). This changes the physical and chemical properties of the SEI film, making it more stable and less prone to gas generation at high temperatures while maintaining ion conductivity
2Productivity
If ethylene sulfite is added to improve initial capacity and reduce expansion, then the charging and discharging performance is improved, but the SEI film stability deteriorates leading to increased interface resistance
Solution Approach 1:
The patent creates a composite SEI film structure by combining fluorinated cyclic carbonate compounds with other electrolyte components. This composite film integrates the benefits of different materials: the fluorinated compound provides stability and low resistance, while maintaining good ion conductivity, resulting in a multi-functional interface layer
3Reliability
If 1,3-propane sultone is used as a high-voltage additive to form a dense passivation film, then the positive electrode is protected from oxidative decomposition, but the high-temperature storage and cycle performances require further improvement
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by introducing fluorinated cyclic carbonate compounds with specific molecular weights, fluorine content, and cyclic structures. These parameter changes result in a SEI film with optimized properties that provides both high-voltage protection and high-temperature stability
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 enhances electrochemical performance, storage capacity, and self-discharge performance by forming a compact and stable passivation film, reducing gas expansion and maintaining high-temperature performance without battery swelling.
Implementation Method 1
In the first charging process, the compounds of non-aqueous electrolyte first undergo a reduction and decomposition reaction on the surface of the negative electrode, resulting in compounds such as lithium alkoxy, Li2CO3, lithium sulfonate, etc., and a passivation film is formed on the surface of the negative electrode
Implementation Method 2
In the first charging process, the compounds of non-aqueous electrolyte first undergo a reduction and decomposition reaction on the surface of the negative electrode
Implementation Method 3
A good passive SEI film has thermal stability and chemical stability, which not only prevents the electrolyte from further decomposing on the surface of the carbon negative electrode
Implementation Method 4
allows lithium ions to freely enter and exit the electrode while preventing solvent molecules from passing through
Implementation Method 5
allows lithium ions to freely enter and exit the electrode while preventing solvent molecules from passing through
Implementation Method 6
The high-voltage additive, represented by 1,3-propane sultone additive, makes the positive electrode active material contact with the electrolyte and inhibits the oxidative decomposition of the electrolyte under high voltage by preferentially generating oxidation reaction on the positive electrode surface and forming a dense passivation film on the positive electrode surface
Data Source
AI summary
The present application belongs to the technical field of new energy, in particular to a non-aqueous electrolyte for a lithium ion battery and a lithium ion battery. The non-aqueous electrolyte for a lithium ion battery comprises a non-aqueous organic solvent, a lithium salt, and a spiro compound represented by Structural Formula 1. The compound represented by Structural Formula 1 has the characteristic of sulfonate additives to improve high-temperature storage performance of battery, and also has the characteristic of sulfate additives to improve high-temperature cycle performance of battery. A passivation film is deposited on the surface of positive electrode, and functional group X is further crosslinked to make the coated passivation film more compact and stable, which can effectively improve the electrochemical performance of the electrode, the storage performance and self-discharge performance of the battery.