Electrode Tab Fuse Design for Li-Ion Cell Overcharge Protection
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Solution Overview
Problem
Current interrupt devices (CIDs) in Li-ion cells are prone to accidental triggers due to temperature and pressure dependencies, rather than cell voltage, leading to potential unsafe conditions, especially as the cell ages and gas generation changes over its lifetime.
Innovation Solution
Incorporating a fuse mechanism in the electrode tabs of Li-ion cells, which can be configured to disconnect upon reaching high current, voltage, or temperature conditions, ensuring safe disconnection during overcharging or failure scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bi-stable metallic disk is used to disconnect terminals upon excessive gas generation, then safety is improved, but cell performance deteriorates due to unwanted reactions from gassing agents
Solution Approach 1:
The invention removes the gassing agents (such as Li2CO3) from the cell entirely, replacing the gas-generation-based CID mechanism with a direct electrical connection approach. The CID is now directly connected to the electrode tab without requiring chemical gassing, thereby eliminating the unwanted reactions that reduced coulombic efficiency while maintaining safety functionality.
Solution Approach 2:
The invention introduces a thin aluminum layer as an intermediary between the CID and the electrode tab. This intermediate layer serves multiple functions: it provides a low-resistance electrical connection during normal operation, enables precise control of the fusion threshold, and allows the CID to respond to overcharge conditions without requiring chemical gassing agents, thus resolving the contradiction between safety and performance.
2Device complexity
If CIDs are triggered by temperature and pressure rather than voltage, then device simplicity is maintained, but reliability deteriorates due to accidental triggers from age-related gas generation changes
Solution Approach 1:
The invention changes the triggering parameter from temperature/pressure to electrical current/voltage. The CID is designed to fuse when a specific electrical threshold is exceeded, which directly correlates with overcharge conditions. This parameter change eliminates the reliability issues caused by age-related variations in gas generation, as the electrical threshold remains consistent throughout the cell's lifetime.
Solution Approach 2:
The invention segments the CID into distinct functional components: a thin aluminum layer for electrical connection, a fuse element for current threshold detection, and a housing for structural support. This segmentation allows each component to be optimized for its specific function, with the fuse element specifically designed to respond to overcharge electrical conditions rather than general temperature/pressure changes, improving reliability.
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 fuse mechanism effectively protects the battery cell from overcharging by disconnecting electrical communication when critical thresholds are met, thereby preventing further damage and ensuring safety, independent of age-related gas generation changes.
Implementation Method 1
the fuse can include a thin strip of electrically resistive material configured to electrically couple multiple electrodes
Implementation Method 2
the fuse can be configured to deform, break, melt, or otherwise discontinue electrical communication between the electrode and other components
Data Source
AI summary
Apparatus, systems, and methods described herein relate to safety devices for electrochemical cells comprising an electrode tab electrically coupled to an electrode, the electrode including an electrode material disposed on a current collector. In some embodiments, a fuse can be operably coupled to or formed in the electrode tab. In some embodiments, the fuse can be formed by removing a portion of the electrode tab. In some embodiments, the fuse can include a thin strip of electrically resistive material configured to electrically couple multiple electrodes. In some embodiments, the current collector can include a metal-coated deformable mesh material such that the current collector is self-fusing. In some embodiments, the fuse can be configured to deform, break, melt, or otherwise discontinue electrical communication between the electrode and other components of the electrochemical cell in response to a high current condition, a high voltage condition, or a high temperature condition.