Lithium Battery Electrolyte Additives for SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining robust solid electrolyte interface (SEI) formation, leading to non-uniform SEI, swelling, and decreased charge/discharge rates due to inadequate electrolyte solution additives, especially at high and low temperatures.
Innovation Solution
A non-aqueous electrolyte solution incorporating lithium difluoro bis(oxalato)phosphate (LiDFOP), (trimethylsilyl)propyl phosphate (TMSPa), 1,3-propene sultone (PRS), and ethylene sulfate (ESa) as additives, along with imide-based lithium salts like Li(SO2F)2N and LiPF6, to enhance SEI stability and prevent decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solution additives are used or insufficient amounts are used, then manufacturing cost is reduced, but SEI formation becomes non-uniform and battery performance deteriorates
Solution Approach 1:
The patent uses a composite electrolyte additive system comprising four specific components: LiDFOP (lithium difluoro(oxalato)phosphate), TMSPa ((trimethylsilyl)propyl phosphate), PRS (1,3-propene sultone), and ESa (ethylene sulfate). This composite approach allows each additive to contribute different functions - LiDFOP and TMSPa form stable SEI layers, while PRS and ESa suppress gas generation and swelling - achieving uniform SEI formation and improved battery performance through synergistic effects.
Solution Approach 2:
The patent optimizes the concentration parameters of each additive component within specific ranges: LiDFOP (0.5-1.5 wt%), TMSPa (0.1-0.5 wt%), PRS (0.5-1.5 wt%), and ESa (0.5-1.5 wt%). By precisely controlling these parameter values, the patent achieves optimal SEI formation uniformity and suppresses side reactions without requiring excessive additive amounts, thus resolving the contradiction between reliability and device complexity.
2Reliability
If robust SEI is formed to prevent decomposition, then battery stability improves, but charge and discharge rate decreases
Solution Approach 1:
The patent carefully controls the concentration parameters of SEI-forming additives (LiDFOP and TMSPa) within optimal ranges to create a robust yet ion-conductive SEI layer. The SEI thickness and composition are optimized through parameter adjustment - sufficient to prevent electrolyte decomposition and anode swelling, yet thin and conductive enough to allow rapid lithium ion transport, thus resolving the contradiction between stability and charge/discharge rate.
Solution Approach 2:
The patent creates a SEI layer with optimized local properties on the anode surface. The SEI is designed to have high stability and decomposition resistance at the interface between anode and electrolyte, while maintaining high lithium ion conductivity in the transport pathways. This local quality optimization allows the SEI to simultaneously provide protection and facilitate rapid ion transport for high-rate charge/discharge.
3Reliability
If adequate electrolyte solution additive is used to form uniform SEI, then battery performance improves, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the concentration parameters of each additive component within specific ranges to achieve the minimum effective dosage for uniform SEI formation. By precisely controlling these parameters, the patent achieves optimal battery performance with minimized additive amounts - LiDFOP (0.5-1.5 wt%), TMSPa (0.1-0.5 wt%), PRS (0.5-1.5 wt%), and ESa (0.5-1.5 wt%). This parameter optimization resolves the contradiction between reliability and quantity of substance.
Solution Approach 2:
The patent employs a composite additive system where four different additives work synergistically to achieve uniform SEI formation and performance improvement at lower overall concentrations. Each component contributes specific functions, allowing the system to achieve better performance with less total additive material compared to using single additives at higher concentrations.
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 improves high and low-temperature output characteristics, suppresses decomposition, and reduces swelling by forming a stable SEI, maintaining lithium ion mobility and battery efficiency.
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
suppresses decomposition, and reduces swelling by forming a stable SEI
Implementation Method 3
the SEI may only pass the lithium ions by acting as an ion tunnel
Implementation Method 4
suppresses decomposition, and reduces swelling by forming a stable SEI, maintaining lithium ion mobility and battery efficiency
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.