Non-Aqueous Electrolyte Composition for High-Temperature Li-Ion Storage
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Solution Overview
Problem
Lithium ion batteries face insufficient high-temperature storage performance and high-temperature cycle performance due to issues with gas production and passivation film stability in existing non-aqueous electrolytes.
Innovation Solution
A non-aqueous electrolyte for lithium ion batteries is developed, comprising a bicyclic sulfate compound and a compound A represented by structural formula 1, which forms a composite passivation film with improved thermal stability, inhibiting gas expansion and enhancing high-temperature storage and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If vinylene carbonate is added to the electrolyte to form a passivation film on the negative electrode, then the cycle performance of the battery is improved, but the battery generates gas during high-temperature storage causing expansion
Solution Approach 1:
The patent uses a composite electrolyte system combining vinylene carbonate (VC) with fluoroethylene carbonate (FEC) and a bicyclic sulfate compound. This composite approach leverages the film-forming capability of VC while FEC and the bicyclic sulfate compound suppress gas production, achieving both cycle performance improvement and reduced high-temperature gas expansion through synergistic interaction of multiple additives
2Reliability
If vinylene carbonate is added to form a passivation film, then further decomposition of electrolyte is prevented, but the passivation film has high impedance affecting low-temperature performance and safety
Solution Approach 1:
The patent modifies the passivation film properties by changing its chemical composition through the addition of FEC and bicyclic sulfate compound alongside VC. This parameter change in film composition creates a dual-layer structure where the inner layer provides decomposition prevention while the outer layer maintains lower impedance, thus improving both reliability and low-temperature performance
3Ease of operation
If fluoroethylene carbonate is added to form a passivation film with low impedance, then low-temperature discharge performance is improved, but more gas is produced during high-temperature storage reducing storage performance
Solution Approach 1:
The patent merges the benefits of FEC (low impedance, good low-temperature performance) with VC (decomposition prevention) and bicyclic sulfate compound (gas suppression). The combined additive system creates a passivation film that inherits low impedance characteristics from FEC while the bicyclic sulfate compound counteracts gas production, achieving both low-temperature ease of operation and reduced high-temperature gas issues
4Object-generated harmful factors
If a bicyclic sulfate compound is added to inhibit gas production during high-temperature storage, then high-temperature storage performance is improved, but high-temperature cycle performance still needs further improvement
Solution Approach 1:
The patent applies local quality by creating a differentiated passivation film structure where different regions have different compositions and functions. The bicyclic sulfate compound concentrates in regions where gas suppression is needed, while VC and FEC provide film-forming and low-impedance properties in other regions, achieving both gas inhibition and improved cycle performance through spatially differentiated additive distribution
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 composite passivation film formed by the bicyclic sulfate compound and compound A significantly improves the battery's high-temperature storage capacity retention and cycle performance, reducing gas expansion and maintaining better performance over time.
Implementation Method 1
Vinylene carbonate can take a reduction decomposition reaction on the surface of the negative electrode prior to solvent molecules, and form a passivation film on the surface of the negative electrode
Implementation Method 2
The SEI film formed during the initial charge not only prevents the electrolyte from further decomposing on the surface of the carbon negative electrode, but also acts as a lithium ion tunnel, allowing the passage of only lithium ions
Data Source
AI summary
In order to solve the problems of insufficient high-temperature storage performance and high-temperature cycle performance of the existing lithium ion battery, the present application provides a non-aqueous electrolyte for lithium ion battery, comprising a bicyclic sulfate compound and a compound A represented by structural formula 1. In structural formula 1, R3, R4, R5, R6, R7 and R8 are each independently selected from hydrogen, fluorine atom or a group containing 1˜5 carbon atoms. Meanwhile, the application also discloses a lithium ion battery comprising the non-aqueous electrolyte for lithium ion battery. The non-aqueous electrolyte for lithium ion battery provided by the application is beneficial to improving high-temperature storage and high-temperature cycle performance of battery.