Non-aqueous Electrolyte Dinitrile Additive Suppresses Battery Swelling
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Solution Overview
Problem
Lithium secondary batteries face swelling and potential ignition issues due to gas generation during high-temperature storage, which existing solutions like porous polyolefin separators and additives fail to adequately address without compromising battery capacity or performance.
Innovation Solution
A non-aqueous electrolyte solution incorporating an ionizable lithium salt, an amide compound, and a dinitrile compound with a hetero atom in the substituent bonded to the main chain, which reduces the reaction between dissociated metal ions and the electrolyte, thereby suppressing battery swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous polyolefin-based separator with high melting point is used to prevent battery swelling at high temperature, then thermal stability is improved, but the separator thickness must be increased which reduces battery capacity
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a dinitrile compound with specific structural parameters (hetero atom in substituent, carbon chain length of 1-6). This chemical parameter change enables the electrolyte to form protective films that suppress gas generation at high temperatures without requiring physical changes to the separator structure, thus maintaining battery capacity while improving thermal stability.
2Temperature
If the separator thickness is increased to achieve high melting property, then melting resistance is improved, but the loading amounts of anode and cathode decrease
Solution Approach 1:
The dinitrile compound acts as an intermediary substance that mediates between the electrolyte and electrode surfaces. It forms protective interface films that prevent direct harmful interactions and suppress gas generation, thereby providing thermal stability without requiring increased separator thickness, allowing maximum electrode loading.
3Object-affected harmful factors
If a nonflammable gas is injected into the electrolyte to improve safety, then flame resistance is improved, but the volume of the battery increases and assembly process becomes complicated
Solution Approach 1:
Instead of using permanent nonflammable gas fillings that complicate battery structure and assembly, the patent employs a small amount of dinitrile compound additive (0.01-5 wt%) that performs its safety function temporarily by forming protective films during initial cycles. This approach achieves flame resistance without increasing battery volume or complicating the assembly process.
4Object-affected harmful factors
If a phosphoric acid ester is added to confirm nonflammability, then flame resistance is improved, but the performance of the battery deteriorates due to high reduction potential
Solution Approach 1:
The patent changes the chemical parameters by selecting a dinitrile compound with specific molecular structure (carbon chain length 1-6, hetero atom in substituent) that has appropriate electrochemical potential. This parameter optimization allows the additive to suppress gas generation and improve safety without the high reduction potential problems of phosphoric acid esters, thereby maintaining battery performance.
5Object-affected harmful factors
If a perfluoro compound is added to improve nonflammability, then flame resistance is improved, but a lithium salt precipitates from the organic solvent electrolyte
Solution Approach 1:
Instead of using complex perfluoro compounds that cause lithium salt precipitation, the patent employs a simpler dinitrile compound structure that copies the essential safety function (gas suppression and flame resistance) without the harmful side effects. The simplified molecular structure maintains electrolyte homogeneity and prevents lithium salt precipitation while achieving the desired safety performance.
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 prevents battery swelling and maintains high-temperature stability, improving charging/discharging performance and safety by capturing metal ions, thus enhancing the battery's overall performance and safety.
Implementation Method 1
a dinitrile compound including a hetero atom in a substituent bonded to the main chain to prevent a swelling phenomenon of the battery and a lithium secondary battery including the same
Data Source
Figure 1
AI summary
A non-aqueous electrolyte solution includes an electrolyte solution including an amide compound and a lithium salt, and a dinitrile compound substituted by a hetero atom at a main chain, and a lithium secondary battery includes the non-aqueous electrolyte solution. By using the non-aqueous electrolyte solution, a lithium secondary battery having an improved swelling phenomenon and an increased charging/discharging performance may be provided.