Polymer Film Current Collector With Electrochemical Fuse Regions
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Solution Overview
Problem
Existing lithium secondary batteries face issues with safety due to short circuits, which can lead to overheating and potential explosions, especially in large-capacity batteries, and current collectors made of metal foils do not effectively block short-circuit currents or prevent corrosion.
Innovation Solution
A current collector for electrodes using a polymer film with a conductive material that includes both relatively small and large thickness portions, where the small thickness portions act as an electrochemical fuse to interrupt current flow and block short-circuit currents, reducing thickness and weight compared to metal foil collectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal foil current collector is used, then electrical conductivity is ensured, but the thickness and weight increase, and safety during short circuit is insufficient
Solution Approach 1:
The current collector uses a composite structure combining a polymer film substrate with a conductive material layer. The polymer film provides mechanical support and insulation, while the conductive material layer provides electrical conductivity and fuse functionality, achieving both lightweight construction and safety performance.
Solution Approach 2:
The conductive material layer has non-uniform thickness with thin portions (first thickness) and thick portions (second thickness). The thin portions act as electrochemical fuses that break down during short circuits to block current, while the thick portions maintain electrical connectivity during normal operation, providing localized safety functions without compromising overall conductivity.
2Weight of stationary object
If the current collector thickness is reduced to minimize weight, then weight decreases, but the ability to block short-circuit currents is compromised
Solution Approach 1:
The conductive material layer has non-uniform thickness with thin portions and thick portions. The thin portions serve as sacrificial fuse elements that break down during short circuits, while the thick portions maintain electrical connectivity during normal operation, enabling effective short-circuit protection without requiring uniform thick construction.
Solution Approach 2:
The conductive material layer is segmented into different thickness regions within the same layer structure. This segmentation allows different portions to perform different functions: thin regions for fuse protection and thick regions for current conduction, achieving both weight reduction and safety enhancement.
3Ease of manufacture
If a uniform thickness conductive material layer is used, then manufacturing is simplified, but the electrochemical fuse function cannot be achieved
Solution Approach 1:
The conductive material layer is designed with spatially varying thickness properties. Different regions of the layer have different thicknesses to perform different functions: thin regions for fuse action and thick regions for current conduction, enabling the electrochemical fuse function while maintaining a relatively simple single-layer structure.
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 polymer-based current collector effectively blocks short-circuit currents and prevents overheating by increasing resistance, enhancing battery safety and maintaining energy density, particularly in large-capacity batteries.
Implementation Method 1
the conductive material may include a relatively small thickness portion and a relatively large thickness portion... perform an electrochemical fuse function or a short-circuit current blocking function in the small thickness portion
Data Source
AI summary
According to an embodiment of the present invention, a current collector for an electrode comprises a polymer film, and a conductive material provided on at least one surface of an upper surface or a lower surface of the polymer film, wherein the conductive material may include a relatively small thickness portion and a relatively large thickness portion.