Rechargeable Battery Surface Coatings for Safer Fire Suppression
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Solution Overview
Problem
Rechargeable batteries are prone to thermal runaway and fires due to heat generation during charging and discharging, which can lead to device failures and safety hazards.
Innovation Solution
A rechargeable battery design featuring a hydrophilic layer on one surface and a hydrophobic layer on another, strategically positioned to enhance fire extinguishing efficiency by controlling the flow of fire extinguishing liquids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fire extinguishing liquid is applied to the battery surface, then fire extinguishing efficiency is improved, but the liquid may flow into the battery through the vent portion causing short circuits
Solution Approach 1:
The patent applies different surface properties to different regions: the first surface (larger area) has hydrophilic properties to absorb and retain fire extinguishing liquid, while the second surface (smaller area) containing the vent portion has hydrophobic properties to repel liquid and prevent infiltration. This local differentiation resolves the contradiction by allowing fire extinguishing on the first surface while protecting the vent area from liquid intrusion.
Solution Approach 2:
The hydrophobic layer on the second surface acts as an intermediary barrier between the fire extinguishing liquid and the battery interior. It mediates by selectively repelling the liquid at the vent portion while allowing the hydrophilic layer on the first surface to perform its fire extinguishing function, thus preventing short circuits without compromising fire safety.
2Temperature
If the entire battery surface is made hydrophilic to improve fire extinguishing efficiency, then cooling efficiency is improved, but fire extinguishing liquid may infiltrate through the vent portion
Solution Approach 1:
Instead of uniform hydrophilic coating, the patent implements localized hydrophilic properties on the first surface for optimal cooling, while maintaining hydrophobic properties on the second surface near the vent portion. This spatial differentiation allows high cooling efficiency where needed while preventing liquid infiltration at critical areas.
Solution Approach 2:
The battery surface is segmented into two functional zones: a hydrophilic zone (first surface) for fire extinguishing and cooling, and a hydrophobic zone (second surface) for liquid repellency at the vent area. This segmentation enables each zone to perform its specific function without interfering with the other, resolving the contradiction between cooling efficiency and short circuit prevention.
3Reliability
If the first surface area is increased to improve fire extinguishing coverage, then fire safety is improved, but the battery dimensions increase
Solution Approach 1:
The patent optimizes the area ratio between the first and second surfaces, specifying that the first surface area is greater than the second surface area. This parameter adjustment ensures sufficient fire extinguishing coverage on the larger first surface while keeping the battery compact by limiting the overall surface area through the smaller second surface configuration.
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 hydrophilic and hydrophobic layers effectively manage the application and flow of fire extinguishing liquids, increasing cooling efficiency and preventing fires from spreading to adjacent batteries or devices.
Implementation Method 1
a hydrophilic layer on a first surface of the case
Implementation Method 2
the hydrophilic layer may include a hydrophilic film attached to the first surface of the case, or a hydrophilic paint applied to the first surface of the case
Implementation Method 3
a hydrophobic layer on a second surface of the case
Implementation Method 4
an angle between a water droplet and a surface of the hydrophobic layer may be 100 degrees or more
Data Source
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AI summary
A rechargeable battery includes: an electrode assembly; a case to accommodate the electrode assembly; a hydrophilic layer on a first surface of the case; and a hydrophobic layer on a second surface of the case.