Battery Injection Hole Structure to Prevent Electrolyte Backflow
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Solution Overview
Problem
The existing secondary battery injection structure is prone to capillary phenomena during electrolyte injection, leading to the formation of a liquid film on the injection hole, which can result in electrolyte flow reversal or ejection when the battery is moved due to the small diameter and depth of the vent hole.
Innovation Solution
An injection hole tape with a conical or circular shape and a hollow portion is attached to the lower portion of the injection hole, featuring an adhesive edge region to prevent liquid film formation and reverse flow by reducing the diameter towards the electrode assembly, thereby minimizing capillary effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a vent hole with small diameter and depth corresponding to cap plate thickness is used, then the cap plate structure is simple, but capillary phenomenon occurs causing liquid film formation and electrolyte ejection
Solution Approach 1:
The injection hole is divided into two distinct sections: an upper section with a first diameter and a lower section with a second diameter. This segmentation allows the upper portion to maintain adequate size for reliable electrolyte injection while the lower portion tapers to a smaller diameter to minimize capillary effects and prevent liquid film formation at the hole opening.
Solution Approach 2:
The injection hole exhibits varying diameter along its length, with the upper section having a larger diameter for efficient injection and the lower section having a smaller diameter to reduce capillary action. This local variation in geometric quality optimizes both injection performance and prevents electrolyte ejection.
2Volume of moving object
If the injection hole diameter is small, then the injection structure is compact, but capillary phenomenon causes liquid film formation on the upper portion
Solution Approach 1:
The injection hole is segmented into upper and lower portions with different diameters. The upper portion has a larger diameter that reduces capillary effects and prevents liquid film formation, while the lower portion maintains a smaller diameter for compactness and effective electrolyte delivery.
Solution Approach 2:
The injection hole transitions from a uniform cylindrical geometry to a tapered or conical geometry by varying the diameter along the vertical dimension. This dimensional change allows the hole to achieve both compact volume and reduced capillary phenomenon by controlling the diameter profile from top to bottom.
3Ease of manufacture
If a through-hole injection structure is used, then the manufacturing process is simple, but electrolyte may flow backward or be ejected during battery movement
Solution Approach 1:
The single through-hole is segmented into two functional zones with different diameters. The upper zone with larger diameter accommodates injection flow, while the lower zone with smaller diameter acts as a flow restrictor that prevents backward flow and ejection during battery movement, maintaining electrolyte position stability.
Solution Approach 2:
The diameter parameter of the injection hole is changed along its length rather than maintaining a uniform diameter. This parameter variation creates a flow control effect that allows easy manufacturing through standard drilling while preventing electrolyte ejection through the tapered geometry.
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 improved injection structure effectively prevents the formation of a liquid film on the injection hole, reducing the likelihood of electrolyte ejection during battery movement and ensuring stable electrolyte retention within the battery.
Implementation Method 1
Because a diameter of an injection hole is small, a capillary phenomenon may occur during an injection process or if the injection process is completed. Thus, there may be a problem that a liquid film of an electrolyte is formed on an upper portion of an injection hole
Implementation Method 2
An edge region of the injection hole tape may have an adhesive property
Data Source
AI summary
The present disclosure relates to a secondary battery including an electrode assembly, a case accommodating the electrode assembly and an electrolyte, and a cap assembly including a cap plate coupled to one side of the case, defining an injection hole therethrough, and including an injection hole tape attached to a lower portion of the injection hole.