Lithium-Ion Battery Electrolyte Additives for Gas and Temperature Balance
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to gas generation during charging and discharging, leading to volume swelling, misalignment of terminal sheets, and increased risk of explosion or fire, with performance being unbalanced in high and low temperature environments.
Innovation Solution
A lithium-ion battery electrolyte comprising a non-aqueous solvent, lithium salt, and additives, including a first additive and lithium bis(oxyalyl)difluorophosphate, which improve solubility and form stable films to reduce gas generation and enhance interface stability, thereby balancing high and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commonly used electrolytes with lithium hexafluorophosphate and mixed organic solvents are used, then the battery can operate, but serious gas generation occurs leading to volume swelling and safety issues
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing a fluorinated cyclic carbonate additive with specific molecular structure (containing F, C=O, and cyclic carbonate groups) and optimizing its concentration range (0.1-5 wt%), which fundamentally alters the electrolyte's interaction with electrode surfaces and reduces gas-generating side reactions
Solution Approach 2:
The fluorinated cyclic carbonate additive acts as an intermediary substance that mediates between the electrode surfaces and the bulk electrolyte, forming protective interface films that prevent direct contact and harmful reactions between the electrode and conventional electrolyte components, thereby suppressing gas generation
2Adaptability or versatility
If conventional electrolyte compositions are used, then the battery can function, but performance in high and low temperature environments cannot be comprehensively balanced
Solution Approach 1:
The patent modifies the electrolyte's physical and chemical parameters through the fluorinated additive, which lowers the freezing point and improves low-temperature ionic conductivity while simultaneously enhancing high-temperature stability by forming thermally robust protective films on electrode surfaces
Solution Approach 2:
The fluorinated cyclic carbonate additive performs multiple functions simultaneously: it forms protective SEI films on the negative electrode, stabilizes the positive electrode interface, suppresses gas generation, and enhances both low-temperature fluidity and high-temperature stability, making the electrolyte universally adaptable across temperature extremes
3Productivity
If battery operation continues without intervention, then energy can be stored and delivered, but terminal sheet and separator misalignment occurs due to volume swelling
Solution Approach 1:
The fluorinated cyclic carbonate additive serves as an intermediary that forms protective interface layers on electrode surfaces, preventing the gas-generating side reactions that lead to volume expansion, thereby maintaining battery structural integrity and component alignment during operation
4Temperature
If the electrolyte composition is optimized for low-temperature performance, then low-temperature operation improves, but high-temperature performance and gas generation control deteriorate
Solution Approach 1:
The patent achieves a breakthrough by selecting a fluorinated cyclic carbonate additive with specific molecular characteristics that enable simultaneous optimization: the fluorine atoms and cyclic carbonate structure provide both low-temperature fluidity enhancement and high-temperature interface stability, allowing comprehensive performance balance across the temperature range
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 reduces battery resistance, improves low-temperature performance, and balances high-temperature performance and gas generation, enhancing safety and stability.
Implementation Method 1
improve solubility and form stable films to reduce gas generation and enhance interface stability
Implementation Method 2
During the charging and discharging process of lithium-ion batteries, due to the complexity of chemical reactions, a large amount of gas is generated inside the batteries
Data Source
AI summary
A lithium-ion battery electrolyte, a lithium-ion battery, and an electrochemical apparatus are provided. The electrolyte includes a non-aqueous solvent, a lithium salt, and an additive including a first additive and a second additive. The first additive is selected from compounds represented by formula (I), and the second additive is lithium bis(oxyalyl)difluorophosphate, and where R1, R2, R3, and R4 are each independently a substituent having 1 to 3 carbon atoms, 0 to 4 unsaturations, and 0 to 3 heteroatoms, the heteroatoms are selected from at least one of nitrogen, phosphorus, or sulfur, and n is 0 to 2.