Non-Aqueous Electrolyte Additives for Stable SEI in Lithium Batteries
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in maintaining high-temperature stability and life characteristics due to electrolyte decomposition reactions at the electrode-electrolyte interface, particularly when using high-energy density but low-stability positive electrode materials and silicon-based negative electrodes.
Innovation Solution
A non-aqueous electrolyte solution containing silane-based compounds and other additives forms a stable and low-resistance solid electrolyte interface (SEI) layer through covalent and carbon-carbon bonds, enhancing mechanical stiffness and reducing electrolyte decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-energy density positive electrode materials are used to increase capacity, then battery capacity is improved, but electrode stability deteriorates due to low stability of the positive electrode material
Solution Approach 1:
An artificial solid electrolyte interface (SEI) layer is introduced as an intermediary between the positive electrode material and the electrolyte solution. This SEI layer, formed by silane-based compounds, acts as a protective barrier that stabilizes the positive electrode material surface, preventing direct harmful interactions while allowing the high-capacity material to function.
Solution Approach 2:
The invention creates a model SEI layer structure using silane-based compounds that mimics the protective function of natural SEI layers. This artificial SEI layer copies the essential protective characteristics needed to stabilize the positive electrode material, providing a template for effective interface protection.
2Ease of manufacture
If conventional electrolyte solutions are used, then battery assembly is simple, but electrolyte decomposition occurs at the electrode-electrolyte interface during high-temperature operation, degrading life characteristics
Solution Approach 1:
The invention modifies the chemical composition parameters of the electrolyte solution by incorporating specific silane-based compounds (Formula I) in controlled amounts (0.01-10 parts by weight per 100 parts electrolyte solution). This parameter change transforms the electrolyte's behavior at the electrode interface, enabling stable SEI layer formation that prevents decomposition during high-temperature operation.
Solution Approach 2:
The electrolyte solution is formulated as a composite system combining conventional electrolyte components with silane-based compounds. This composite electrolyte maintains the beneficial properties of conventional electrolytes while adding the protective functionality of silane-derived SEI layers, achieving both ease of manufacture and improved reliability.
3Quantity of substance
If silicon-based negative electrode materials are used to increase capacity, then battery capacity is improved, but surface species decomposition occurs in the electrolyte solution causing side reactions
Solution Approach 1:
The silane-based compounds in the electrolyte solution perform preliminary protective action by forming a stable SEI layer on the silicon-based negative electrode surface before harmful decomposition reactions can occur. This pre-formed protective layer prevents the electrolyte from attacking the silicon surface species, eliminating side reactions.
Solution Approach 2:
The invention converts the naturally occurring but harmful interaction between electrolyte and silicon surface species into a beneficial process. The controlled reaction of silane-based compounds with the electrode surface creates a protective SEI layer, transforming what would be detrimental decomposition into a useful protective mechanism.
4Duration of action of moving object
If repeated charge-discharge cycles are performed during formation process, then battery activation is achieved, but electrolyte decomposition accumulates due to redox reactions at the interface, increasing resistance and degrading life characteristics
Solution Approach 1:
The silane-based compounds perform preliminary protective action during the formation process by forming a stable SEI layer that prevents cumulative electrolyte decomposition. This preliminary protection ensures that repeated charge-discharge cycles during activation do not lead to progressive damage, thereby preserving long-term life characteristics.
Solution Approach 2:
The SEI layer formed by silane-based compounds acts as a cushioning barrier before harmful decomposition can accumulate. This protective layer absorbs and mitigates the effects of redox reactions at the electrode-electrolyte interface during formation, preventing the accumulation of decomposition products that would otherwise increase resistance and degrade 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 provides lithium secondary batteries with improved high-temperature stability and extended life characteristics by forming a robust SEI layer that withstands volume changes and reduces internal resistance.
Implementation Method 1
forms a stable and low-resistance solid electrolyte interface (SEI) layer through covalent and carbon-carbon bonds
Implementation Method 2
lithium ions from the lithium-containing transition metal oxide used as the positive electrode during the charge move to the carbon negative electrode active material used as the negative electrode and are intercalated thereinto
Implementation Method 3
an electrolyte decomposition reaction due to a redox reaction occurring at an interface between the electrolyte and the electrode is accumulated during repeated cycles
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution that may improve high-temperature stability and life characteristics of a lithium secondary battery by forming a thin and stable SEI layer, wherein it relates to a non-aqueous electrolyte solution including an organic solvent; a lithium salt; the compound represented by Formula I described in this specification; and at least one selected from the compounds represented by Formula II to Formula V described in this specification, and a lithium secondary battery including the same.