Battery Separator Overhang and Electrolyte Ratio for Fast Charging
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Solution Overview
Problem
Lithium-ion batteries with fast charging capabilities face safety issues due to separator shrinkage at high temperatures, leading to potential short-circuits and thermal runaway.
Innovation Solution
Optimizing the overhang of the separator and the content of carbonate solvent in the electrolyte solution to maintain high electrical conductivity while reducing separator shrinkage at high temperatures, adhering to the condition 1.5≤A/B≤12, where A is the overhang of the separator and B is the mass percentage of the carbonate solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbonate solvent is used to improve electrolyte solution conductivity, then fast charging capability is improved, but separator shrinkage rate increases at high temperature
Solution Approach 1:
The patent optimizes the content ratio of carbonate solvent in the electrolyte solution and the overhang dimension of the separator to satisfy a specific mathematical relationship. This parameter optimization allows the battery to achieve high conductivity for fast charging while limiting separator shrinkage through the controlled overhang compensation mechanism.
Solution Approach 2:
The separator is designed with an overhang that extends beyond the electrode plates, creating a protective margin before thermal runaway can occur. This pre-designed overhang acts as a safety buffer that compensates for expected thermal expansion and shrinkage, preventing direct contact between electrodes even when the separator shrinks at high temperatures.
2Reliability
If separator overhang is increased to prevent short-circuit, then safety is improved, but fast charging capability is reduced
Solution Approach 1:
The patent establishes a precise mathematical relationship between separator overhang (A) and carbonate solvent content (B), where 1.5≤A/B≤12. This optimized ratio ensures that the separator has sufficient overhang to prevent short-circuits during thermal events, while the controlled carbonate solvent content maintains high electrolyte conductivity for fast charging 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 optimized battery design enhances both fast charging performance and safety by reducing separator shrinkage and preventing thermal runaway, thus ensuring a higher hot box pass rate and improved temperature control.
Implementation Method 1
the electrolyte solution includes a lithium salt, an organic solvent, and an additive
Implementation Method 2
improving a conductivity of an electrolyte solution is conducive to improving fast charging capability of a battery, and the most commonly used method for improving a conductivity of an electrolyte solution is to use a carbonate solvent
Implementation Method 3
the battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte solution
Data Source
AI summary
Disclosed are a battery including a positive electrode plate, a negative electrode plate, a separator, and an electrolyte solution. The electrolyte solution includes a lithium salt, an organic solvent, and an additive, and the organic solvent includes at least one carbonate solvent; and the battery satisfies following condition: 1.5≤A/B≤12, where A denotes an overhang of the separator, in a unit of mm; B denotes a mass percentage of the carbonate solvent in the organic solvent. According to the present disclosure, an overhang of a separator and a content of a carbonate solvent in an electrolyte solution are optimized, thereby reducing a shrinkage of the separator in a high-temperature environment.