Cylindrical Lithium Battery Cap Venting for Low Resistance
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Solution Overview
Problem
Existing cylindrical lithium battery caps have high internal resistance and fail to timely break the notch on the explosion-proof disc under high internal pressure, posing a risk of thermal runaway and safety hazards.
Innovation Solution
A new cap design featuring a steel sheet with a through hole, an explosion-proof disc with a wrap edge extending to the hole, a spacer ring, and a seal ring, which reduces contact resistance and creates a sufficient explosion venting area, ensuring timely rupture and gas escape when internal pressure rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional multi-component cap structure is used, then the cap provides basic sealing and explosion-proof functions, but the internal resistance becomes high and the notch cannot break timely under high pressure
Solution Approach 1:
The patent merges the steel cap and explosion-proof disc into an integrated structure where the explosion-proof disc is directly formed on the steel cap surface, eliminating the need for separate components and reducing assembly complexity while maintaining explosion-proof functionality
Solution Approach 2:
The patent segments the cap structure by defining a through hole in the steel cap and forming the explosion-proof disc with a notch as a distinct functional zone, allowing independent optimization of each component's properties
2Strength
If a nickel-plated steel cap is used, then the cap provides structural strength, but the contact resistance between aluminum wire and cap is high
Solution Approach 1:
The patent removes the nickel plating layer from the steel cap surface and replaces it with an aluminum explosion-proof disc that provides both structural integrity and low contact resistance for aluminum wire welding
Solution Approach 2:
The patent creates a composite structure combining steel cap (for strength) with aluminum explosion-proof disc (for low resistance), optimizing both mechanical properties and electrical conductivity
3Reliability
If the notch on the explosion-proof disc is designed for pressure release, then explosion-proof function is provided, but under high internal pressure the notch cannot break in time leading to thermal runaway risk
Solution Approach 1:
The patent pre-defines a through hole in the steel cap and positions the explosion-proof disc with notch to align with it, ensuring that when pressure builds up, the notch breaks and gases can immediately escape through the pre-prepared opening without delay
Solution Approach 2:
The patent transitions from a two-dimensional notch breaking mechanism to a three-dimensional pressure release system by creating a through hole that extends through the entire cap thickness, providing a direct escape path for gases in the vertical dimension
Data Source
AI summary
The present application provides a new type of cap for a cylindrical lithium battery, which includes a steel sheet, an explosion-proof sheet, a connection piece, a spacer ring and a seal ring. The steel sheet is defined with a through hole. The explosion-proof disc is arranged on one side of the steel sheet, and the explosion-proof disc is provided with a wrap edge, and the wrap edge is extended from an edge of the steel sheet to another side of the steel sheet and then to an edge of the through hole. The middle portion of the connection piece is in contact with the middle portion of the explosion-proof disc. The spacer ring is arranged between the explosion-proof disc and the connection piece. The seal ring is arranged around the explosion-proof disc, the connection piece and the spacer ring.