Nonaqueous Battery Electrolyte Composition for Low Cathode Resistance
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with increased positive electrode resistance due to electrolyte oxidation and decomposition during charge/discharge cycles, leading to reduced durability and quick charge performance.
Innovation Solution
Incorporating an organic sulfuric acid salt represented by the formula (R—O—SO3)nX1, along with ethylene carbonate and fluoroethylene carbonate in the electrolyte, which delocalizes negative charge and suppresses side reactions, thereby reducing positive electrode resistance and improving battery durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode potential is increased to charge deeper during charging, then the charging capacity is improved, but the oxidation and decomposition of the electrolyte is accelerated, increasing the positive electrode resistance and reducing durability
Solution Approach 1:
A coating layer comprising a dielectric and a carbonate compound is formed on the positive electrode active material surface. This coating layer acts as an intermediary between the electrolyte and the positive electrode active material, suppressing direct contact and harmful side reactions, thereby enabling deep charging while maintaining durability by preventing electrolyte oxidation and decomposition
Solution Approach 2:
The coating layer is formed as a composite structure combining a dielectric material and a carbonate compound. This composite material provides both the electrical insulation properties of the dielectric and the protective characteristics of the carbonate compound, effectively suppressing electrolyte decomposition while allowing deep charging operations
2Productivity
If the positive electrode resistance is decreased to improve quick charge characteristics, then the charging rate is improved, but the positive electrode potential increases easily, accelerating electrolyte oxidation and reducing durability
Solution Approach 1:
The coating layer serves as a protective intermediary that allows rapid ion transport (improving quick charge characteristics) while simultaneously preventing harmful electrolyte oxidation reactions, thus maintaining durability even at high charging rates
Solution Approach 2:
The coating layer modifies the surface properties of the positive electrode active material, changing the interfacial parameters to enable fast ion transport while suppressing parasitic reactions, thereby achieving both quick charge characteristics and durability
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 protects the positive electrode active material surface, enhancing quick charge acceptance and maintaining battery durability by suppressing the formation of high resistance coatings, even during deep charging and repeated charge/discharge cycles.
Implementation Method 1
the organic sulfuric acid salt represented by a formula (1), and ethylene carbonate and fluoroethylene carbonate, 0.1≤Vec/Vfec≤15 is satisfied, wherein the organic sulfuric acid salt works to prevent a high resistance coating to be formed on the positive electrode active material surface
Implementation Method 2
the oxidation and decomposition of the electrolyte is accelerated during charge/discharge cycles, increasing the positive electrode resistance
Data Source
AI summary
The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The electrolyte includes an organic sulfuric acid salt represented by a formula (1): (R—O—SO3)nX1, where R is an organic group with 1 or more carbon atoms, X1 is a cation, and n is an integer of 1 to 3. The electrolyte further includes ethylene carbonate and fluoroethylene carbonate. The ethylene carbonate volume Vec and the fluoroethylene carbonate volume Vfec satisfy 0.1≤Vec/Vfec≤15.