Wire Bond Fusing for Electrochemical Cell Cascade Protection
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Solution Overview
Problem
Lithium Ion electrochemical cells are volatile and require improved fusing solutions that can function as both current carriers and precise fusing elements, capable of withstanding various conditions and applications, as conventional fuses have limitations in endurance and safety.
Innovation Solution
The use of wire bonds as fusing elements, systematically designed to conduct current during normal operation and sever electrical connections when a predetermined current exceeds a threshold for a specific period, allowing for series or parallel connections and selected based on attributes like wire length, diameter, and material to ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fuses are used for electrochemical cells, then current protection is provided, but the fuses have limitations in endurance, safety, and cannot function as current carriers
Solution Approach 1:
The patent combines the current carrier function and fusing element function into a single wire bond structure. The wire bond serves dual purposes: conducting current during normal operation and acting as a fusible element that severs the electrical connection when excessive current flows, eliminating the need for separate components and improving reliability.
Solution Approach 2:
The wire bond is designed to perform multiple functions simultaneously: it acts as an electrical conductor during normal operation and as a protective fusing element when fault conditions occur. This multi-functionality reduces device complexity while enhancing safety and endurance of the electrochemical cell assembly.
2Reliability
If wire bonds are designed to sever at high current, then safety is improved by preventing cascade failures, but the wire bond must be precisely selected to avoid premature failure
Solution Approach 1:
The patent systematically varies wire bond parameters including material composition, diameter, length, and coating to achieve desired fusing characteristics. By adjusting these parameters, the wire bond can be precisely tuned to sever at specific current thresholds and time durations, preventing cascade failures while avoiding premature failure through careful parameter selection within defined regions of Ft plots.
3Measurement precision
If wire bond attributes are optimized for fusing characteristics, then precise current protection is achieved, but the selection process becomes more complex
Solution Approach 1:
The patent applies different properties to different aspects of the wire bond: the base material provides electrical conductivity and mechanical strength, while specific coatings or alloying elements provide controlled fusing characteristics at precise current thresholds. This local differentiation of properties allows precise current protection while managing selection complexity through systematic design guidelines.
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 wire bond fusing elements provide enhanced safety by preventing cascade failures, reducing the risk of short-circuit damage, and allowing continued operation of the cell assembly, while being more compact, lightweight, and capable of withstanding higher voltages and vibrations compared to conventional fuses.
Implementation Method 1
each wire bond is selected to conduct current from a respective cell during normal operation
Implementation Method 2
to sever such electrical connection through the wire bond when a predetermined current exceeds a threshold value for a predetermined period of time
Data Source
AI summary
Cell assemblies and methods for assembling cell assemblies include installing a plurality of cells within a cell housing and electrically connecting each cell to each other cell through at least one wire bond, wherein each wire bond is selected to conduct current from a respective cell during normal operation and to sever such electrical connection through the wire bond when a predetermined current exceeds a threshold value for a predetermined period of time.