Striped Al-F Separator Coating for Battery Thermal and Cycle Stability
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Solution Overview
Problem
Existing electrochemical apparatuses face challenges in maintaining puncture resistance, thermal safety, and electrochemical performance under high-temperature and low-temperature conditions, particularly in applications like energy storage systems and electric vehicles.
Innovation Solution
A separator with specific atomic ratios of aluminum and fluorine atoms, along with a coating design featuring spaced stripes, enhances puncture resistance, improves liquid retention, and optimizes bonding forces between electrodes, thereby improving thermal safety and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the atomic percentage of aluminum atoms is increased to improve puncture resistance, then the puncture resistance improves, but the risk of separator puncture increases when the ratio is excessively high
Solution Approach 1:
The patent optimizes the atomic percentage ratio of aluminum atoms to fluorine atoms within the specific range of 1≤A≤4 to achieve the best balance between puncture resistance and safety. This parameter optimization prevents both insufficient protection and excessive rigidity that could lead to puncture
Solution Approach 2:
The separator uses a composite coating containing both aluminum atoms and fluorine atoms in controlled proportions. This composite structure combines the puncture resistance enhancement from aluminum with the safety and affinity benefits from fluorine, resolving the contradiction between strength and reliability
2Reliability
If the atomic percentage of fluorine atoms is increased to improve affinity with electrolyte solution, then the liquid retention capability improves, but the manufacturing complexity increases
Solution Approach 1:
The patent specifies a controlled atomic percentage range for fluorine atoms within the coating to optimize liquid retention capability. By defining precise compositional parameters, the patent achieves reliable electrolyte affinity while maintaining manufacturability through standardized material formulations
3Force
If the average spacing between stripes is decreased to improve interface bonding force, then the bonding strength improves, but the liquid retention capacity decreases
Solution Approach 1:
The patent optimizes the average spacing between stripes within the range of 1 mm to 3 mm to achieve the optimal balance between interface bonding force and liquid retention capacity. This parameter optimization ensures both strong electrode attachment and sufficient electrolyte storage
4Temperature
If the separator is designed for high puncture resistance at high temperature, then the thermal safety improves, but the low-temperature cycle performance deteriorates
Solution Approach 1:
The patent employs a composite coating with specific aluminum and fluorine atomic ratios that provides thermal stability at high temperatures while maintaining flexibility and ion transport capability at low temperatures. This composite structure resolves the temperature-dependent performance contradiction
Solution Approach 2:
The striped coating structure provides localized reinforcement for thermal safety where needed, while the spacing between stripes maintains porosity and flexibility for low-temperature performance. Different regions of the separator serve different functional requirements
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 separator design reduces short-circuit risks, enhances thermal safety, and improves high-temperature and low-temperature cycle performance, while maintaining structural stability and lithium ion transport efficiency.
Implementation Method 1
the surface of the separator has the appropriate atomic percentages of the aluminum atoms and the fluorine atoms, which can effectively improve the puncture resistance of the separator at 35° C.
Implementation Method 2
the fluorine atoms can effectively improve the affinity between the surface of the separator and the electrolyte solution, which is more conducive to improving the liquid retention capability of the electrochemical apparatus during cycling
Implementation Method 3
When the average spacing between two adjacent stripes falls within an appropriate range, it is conducive to improving the interface bonding force between the separator and the positive/negative electrode plates
Data Source
AI summary
A separator comprises aluminum atoms and fluorine atoms, and in a 2 μm×2 μm region, a ratio A of atomic percentages of the aluminum atoms to the fluorine atoms satisfies 1≤A≤4. The separator includes a substrate, and the surface of the substrate is provided with a coating. The coating includes a plurality of spaced stripes, and an average spacing between two adjacent stripes is 1 mm to 3 mm. The separator provided in this application can improve the high-temperature cycle performance, low-temperature intermittent cycle performance, and thermal safety performance of the electrochemical apparatus.