Integrated Cap Plate Terminal and Membrane for Battery Overcharge Protection
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Solution Overview
Problem
Secondary batteries face challenges in safely managing overcharge and short-circuit conditions, as existing designs lack effective mechanisms to cut off charging and short-circuit currents, which can lead to safety issues and reduced stability.
Innovation Solution
The integration of a positive electrode terminal and membrane into a cap plate, with a fuse connected to the current collector plate, allows for the automatic cutoff of charging currents during overcharge by inverting the membrane under pressure and melting the fuse during short-circuits to prevent further current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate membrane and terminal design is used, then the battery structure is simpler, but the ability to automatically cut off charging current during overcharge is insufficient
Solution Approach 1:
The patent combines the membrane and terminal into a single integrated cap plate structure. The membrane is positioned on the cap plate and electrically connected to the terminal, forming a unified component that performs both mechanical support and electrical functions. This integration allows the membrane to effectively cut off charging current during overcharge conditions while maintaining structural simplicity.
2Reliability
If no fuse is installed, then the device complexity is reduced, but the ability to cut off short-circuit current is lost
Solution Approach 1:
The fuse is integrated into the cap plate structure, specifically positioned to connect the membrane to the current collector plate. This integration allows the fuse to perform short-circuit protection functions without requiring separate external components. When a short-circuit occurs, the fuse melts to cut off the current path, providing reliable protection while maintaining structural compactness.
3Strength
If the membrane thickness is increased, then the mechanical strength is improved, but the responsiveness to gas pressure for current cutoff is reduced
Solution Approach 1:
The membrane is designed with non-uniform thickness distribution, being thinner at the center and thicker at the edges. This local quality variation allows the central region to be highly responsive to gas pressure for rapid inversion and current cutoff, while the thicker edges provide sufficient mechanical support and structural integrity. The optimized thickness distribution balances both mechanical strength and responsiveness 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
This design effectively prevents overcharge and short-circuit damage by interrupting current paths, enhancing the safety and stability of secondary batteries.
Implementation Method 1
the membrane may be inverted from the pressure of the gases being transmitted to the terminal cavity, the gases are generated when the secondary battery is overcharged
Implementation Method 2
the fuse may be melted by a short-circuit current to cut off a short-circuit current path
Data Source
AI summary
Various examples provide a secondary battery having a positive electrode terminal-and-membrane integrated cap plate, which can cut off a charging current in an overcharge mode by integrating a positive electrode terminal and a membrane into the cap plate, and can cut off a short-circuit current in an external short-circuit mode by placing a fuse in a region of the membrane connected to the current collector plate. In one example embodiment, the secondary battery may include a case having an opening, an electrode assembly housed in the opening of the case housed in the opening of the case, and a cap plate coupled to the opening of the case, wherein the cap plate may include a terminal portion integrated into the cap plate, and a membrane integrated into the terminal portion to be electrically connected to the electrode assembly.