Electrolyte Additives for Lithium Battery SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with non-uniform solid electrolyte interface (SEI) formation, leading to poor low-temperature output characteristics and potential swelling or gas generation due to electrolyte solution decomposition, especially when the electrolyte solution additive is not optimally adjusted.
Innovation Solution
A non-aqueous electrolyte solution comprising an imide-based lithium salt, such as Li(SO2F)2N, and specific additives like lithium difluoro bis(oxalato)phosphate (LiDFOP), (trimethylsilyl)propyl phosphate (TMSPa), 1,3-propene sultone (PRS), and ethylene sulfate (ESa), which improve SEI stability and prevent decomposition, thereby enhancing high and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrolyte solution additive is not optimally adjusted, then the battery structure remains simple, but non-uniform SEI formation occurs leading to poor low-temperature output characteristics and potential swelling or gas generation
Solution Approach 1:
The patent applies parameter changes by optimizing the concentration ratios of specific additives (cyclic carbonate 5-20 wt%, chain carbonate 80-95 wt%, and additive compounds 0.01-5 wt%) in the electrolyte solution. This precise parameter adjustment ensures uniform SEI formation while maintaining battery reliability across temperature ranges without excessive complexity
Solution Approach 2:
The patent uses composite materials by combining multiple electrolyte components (cyclic carbonate, chain carbonate, and additive compounds containing fluorinated cyclic carbonate or sultone groups) to create a synergistic electrolyte system. This composite approach produces uniform SEI formation and prevents swelling/gas generation while managing the complexity through standardized composition ratios
2Reliability
If the SEI is not robust, then the electrolyte solution can freely solvate lithium ions improving ion mobility, but the carbon anode structure is destroyed due to co-intercalation
Solution Approach 1:
The patent applies preliminary anti-action by incorporating specific additive compounds (fluorinated cyclic carbonate or sultone groups) into the electrolyte solution before battery operation. These additives proactively form a robust SEI layer during initial charging cycles that prevents subsequent electrolyte decomposition and co-intercalation damage to the carbon anode structure
Solution Approach 2:
The patent uses intermediary substances (additive compounds containing fluorinated cyclic carbonate or sultone groups) that mediate between the electrolyte solution and the carbon anode. These intermediaries form the SEI layer that acts as a protective barrier, allowing lithium ion transport while preventing harmful electrolyte decomposition and anode structure destruction
3Reliability
If the input of electrolyte solution additive is not adjusted to required amount, then the electrolyte solution composition remains simple, but robust SEI cannot be formed leading to swelling phenomenon and increased gas generation
Solution Approach 1:
The patent applies parameter changes by precisely controlling the amount of additive compounds (0.01-5 wt% of total electrolyte solution weight) and the ratio of cyclic to chain carbonates (5:95 to 20:80). This parameter optimization ensures sufficient additive concentration to form robust SEI that prevents swelling and gas generation while avoiding excessive complexity in the electrolyte formulation
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 suppresses electrolyte decomposition, maintains lithium ion mobility, and forms a stable SEI, resulting in improved output characteristics and extended battery life by reducing interfacial resistance and impedance.
Implementation Method 1
a film may be formed on the surface of the anode. The film is denoted as 'solid electrolyte interface (SEI)'
Implementation Method 2
the SEI may only pass the lithium ions by acting as an ion tunnel
Implementation Method 3
organic solvents of an electrolyte solution having a high molecular weight which solvates lithium ions and moves therewith
Data Source
AI summary
Provided is a non-aqueous electrolyte solution including a non-aqueous organic solvent, an imide-based lithium salt, and at least one additive selected from the group consisting of lithium difluoro bis(oxalato)phosphate (LiDFOP), (trimethylsilyl)propyl phosphate (TMSPa), 1,3-propene sultone (PRS), and ethylene sulfate (ESa), as an electrolyte solution additive.According to the electrolyte solution additive for a lithium secondary battery of the present invention, the electrolyte solution additive may improve output characteristics at high and low temperatures and may prevent a swelling phenomenon by suppressing the decomposition of PF6− on the surface of a cathode, which may occur during a high-temperature cycle of a lithium secondary battery including the electrolyte solution additive, and preventing an oxidation reaction of an electrolyte solution.