Non-Aqueous Electrolyte Composition for Stable Lithium Battery SEI
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Solution Overview
Problem
Lithium secondary batteries face limitations in high-temperature storage characteristics and cycle life due to the use of ethylene carbonate as an organic solvent, which results in reduced performance at high temperatures and low temperatures, and increased irreversible capacity.
Innovation Solution
A non-aqueous electrolyte solution is developed, comprising a lithium salt at a concentration of 1.2 M to 3.3 M, ethylene carbonate as a first organic solvent in amounts up to 10 wt%, and an oligomer with a specific structure as an additive, along with other compounds like fluorine-containing aromatic compounds, carbonate ester compounds, and acid anhydrides, to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ethylene carbonate is used as an organic solvent to improve output characteristics, then output characteristics are improved, but high-temperature storage characteristics and low-temperature output characteristics are degraded
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a specific cyclic carboxylate compound (Formula 1) with controlled molecular structure and adding it in a specific concentration range (0.01-5 wt%). This parameter change modifies the SEI formation characteristics, allowing the battery to achieve both good output characteristics and improved high-temperature storage stability.
Solution Approach 2:
The patent creates a composite electrolyte system by combining ethylene carbonate with a cyclic carboxylate compound (Formula 1) and other additives. This composite approach leverages the high dielectric constant of ethylene carbonate for good output characteristics while the cyclic carboxylate compound contributes to thermal stability and forms a more robust SEI, resolving the contradiction between power and reliability.
2Ease of manufacture
If conventional electrolyte solution composition is used, then manufacturing is simple, but irreversible capacity increases and output characteristics are degraded due to SEI degradation
Solution Approach 1:
The patent introduces a cyclic carboxylate compound (Formula 1) with specific structural parameters and controls its concentration within 0.01-5 wt%. This parameter change enhances SEI stability and prevents degradation, thereby improving output characteristics and reducing irreversible capacity while maintaining relatively simple manufacturing processes.
Solution Approach 2:
The cyclic carboxylate compound performs a preliminary action by forming a stable SEI layer during initial charging cycles. This pre-formed protective layer prevents subsequent SEI degradation and continuous side reactions, thereby improving long-term output characteristics and reducing irreversible capacity loss without complicating the manufacturing process.
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-temperature and low-temperature stabilities, reduces resistance during charge and discharge, and extends cycle life by forming a robust solid electrolyte interface, thereby enhancing the battery's storage characteristics and output characteristics.
Implementation Method 1
a film is formed on a surface of the negative electrode... The film is denoted as 'solid electrolyte interface (SEI)'... the SEI formed at an initial stage of charging prevents a reaction of the lithium ions with the carbon negative electrode or other materials during charge and discharge. Also, the SEI only passes the lithium ions by acting as an ion tunnel.
Implementation Method 2
the SEI only passes the lithium ions by acting as an ion tunnel... the non-aqueous electrolyte solution having improved high-temperature and low-temperature stabilities... reduces resistance during charge and discharge
Data Source
AI summary
The present invention relates to a non-aqueous electrolyte solution and a lithium secondary battery including the same, and, particularly, to a non-aqueous electrolyte solution, which includes a 1.2 M to 3.3 M lithium salt, a first organic solvent composed of ethylene carbonate, a second organic solvent excluding the ethylene carbonate, and an oligomer represented by Formula 1 as a first additive, wherein the first organic solvent is included in an amount of 0.1 wt% to 12 wt% based on a total weight of the non-aqueous electrolyte solution, and a lithium secondary battery including the same.