Thin Metallized Current Collector Internal Fuse for Lithium Batteries
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Solution Overview
Problem
Lithium batteries are prone to short circuiting and high temperature occurrences, leading to thermal runaway and fires due to manufacturing defects and imperfections in conductive materials, posing safety risks and regulatory challenges.
Innovation Solution
The use of thin metallized current collectors made from materials like aluminum and copper, which become nonconductive upon exposure to high temperatures, creating an internal fuse mechanism within the battery to prevent excessive heat generation during short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thick metal current collectors are used, then mechanical strength and electrical conductivity are maintained, but thermal runaway risk increases during short circuits
Solution Approach 1:
The patent changes the physical parameters of the current collector by reducing metal thickness to ultra-thin levels (1-10 micrometers) and controlling metal content (5-50 wt%), transforming it from a purely structural/conductive component to a safety-responsive component that melts at specific temperatures to break short circuits
Solution Approach 2:
The patent converts the harmful effect of heat generation during short circuits into a beneficial safety mechanism. The thin metal current collector is designed to melt at controlled temperatures (100-500°C), using the heat from short circuits to trigger circuit breaking and prevent thermal runaway
2Reliability
If thin metallized current collectors are used, then internal fuse mechanism is created to prevent thermal runaway, but mechanical strength and conductivity may be compromised
Solution Approach 1:
The patent creates a composite current collector structure combining ultra-thin metal layers (1-10 micrometers) with porous substrates or fiber networks. This composite structure provides both the thermal response characteristics needed for safety and the mechanical integrity required for battery operation
Solution Approach 2:
The patent applies different properties to different parts of the current collector system. The metal coating provides localized conductivity and thermal response, while the underlying substrate provides mechanical strength. The metal content is locally optimized at 5-50 wt% depending on the specific application requirements
3Reliability
If metal content in current collector is reduced to create internal fuse, then safety during short circuit improves, but electrical conductivity decreases
Solution Approach 1:
The patent optimizes the metal content parameter to a specific range (5-50 wt%) that balances conductivity and safety. This parameter change allows the current collector to maintain sufficient conductivity for normal operation while having enough metal content to provide the internal fuse effect during short circuits
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 solution effectively limits current flow and heat generation during short circuits, preventing thermal runaway and enhancing the safety and reliability of lithium batteries by utilizing a thin, thermally unstable current collector that oxidizes at the point of contact, breaking the conductive pathway and preventing further charge movement.
Implementation Method 1
said current collector stops conducting at the point of contact when exposed to a short circuit
Implementation Method 2
When such an event occurs, if the cell is then charged, such a conductive pathway may then cause a discharge of the cell therethrough which ultimately generates excessive heat
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Improvements in the structural components and physical characteristics of lithium battery articles are provided. Standard lithium ion batteries, for example, are prone to certain phenomena related to short circuiting and have experienced high temperature occurrences and ultimate firing as a result. Structural concerns with battery components have been found to contribute to such problems. Improvements provided herein include the utilization of thin metallized current collectors (aluminum and/or copper, as examples), high shrinkage rate materials, materials that become nonconductive upon exposure to high temperatures, and combinations thereof. Such improvements accord the ability to withstand certain imperfections (dendrites, unexpected electrical surges, etc.) within the target lithium battery through provision of ostensibly an internal fuse within the subject lithium batteries themselves that presents undesirable high temperature results from short circuits. Battery articles and methods of use thereof including such improvements are also encompassed within this disclosure.