Lithium Battery Electrolyte Additives for Gas and Resistance Control
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with high-temperature stability and lifetime characteristics due to gas generation and increased resistance, particularly when using high-nickel-based positive electrode active materials and silicon-carbon composite negative electrode active materials.
Innovation Solution
An electrolyte solution for lithium batteries comprising a non-aqueous organic solvent, lithium salt, a first additive with an —OPO— functional group and pyrazole group, and a second additive with a —PO2F functional group, which stabilize thermal decomposition products and form a solid electrolyte interface on the negative electrode, reducing gas generation and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel-based positive electrode active materials and silicon-carbon composite negative electrode active materials are used to increase capacity, then battery capacity is improved, but gas generation and resistance increase at high temperatures
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the high-capacity electrode materials and the electrolyte. This additive forms a stable solid electrolyte interface (SEI) layer that acts as a protective barrier, preventing direct harmful interactions between the electrolyte and electrode materials at high temperatures, thereby suppressing gas generation while maintaining high capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (where R1-R6 represent various hydrocarbon groups and n=0 or 1). This parameter change in the additive's chemical structure enables formation of a more thermally stable SEI layer that resists decomposition at high temperatures, thus improving high-temperature stability without sacrificing capacity
2Device complexity
If conventional electrolyte compositions are used to simplify the system, then device complexity is reduced, but lifetime characteristics deteriorate due to gas generation and resistance increase
Solution Approach 1:
The patent creates a composite electrolyte system by combining conventional carbonate solvents (EC, PC, EMC, DMC) with a specifically designed fluorinated cyclic carbonate additive. This composite composition leverages the beneficial properties of each component: the conventional solvents provide good ionic conductivity and solubility, while the fluorinated additive forms a stable protective interface, achieving extended battery lifetime without excessive complexity
Solution Approach 2:
The patent applies local quality modification by concentrating the fluorinated cyclic carbonate additive at the electrode-electrolyte interface where it forms a localized stable SEI layer. This localized modification at the critical interface region provides enhanced stability and reduced gas generation without requiring complex changes throughout the entire electrolyte bulk composition
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 electrolyte solution enhances high-temperature stability and lifetime characteristics by minimizing gas generation and resistance, improving battery performance with high-nickel and silicon-carbon composite materials.
Implementation Method 1
stabilize thermal decomposition products
Implementation Method 2
form a solid electrolyte interface on the negative electrode
Data Source
AI summary
The present disclosure relates to an electrolyte solution for a rechargeable lithium battery and a rechargeable lithium battery including the same, wherein the electrolyte solution includes a non-aqueous organic solvent, a lithium salt, a first additive and a second additive.