Electrode for rechargeable battery and electrode assembly and rechargeable lithium battery including the same
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Solution Overview
Problem
Rechargeable batteries with different-sized electrodes are prone to short circuits and sudden heat increases due to concentrated electric current, which can lead to ignition or explosion, especially when quickly charged or when materials with low thermal conductivity are used as insulating layers.
Innovation Solution
An electrode design featuring a substrate with an active portion and an uncoated portion, a functional layer with a higher resistance than the substrate but lower than the active material layer, and an active material layer, where the functional layer extends to the uncoated portion to reduce contact resistance and prevent short circuits and heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If materials with relatively low thermal conductivity are utilized as the insulating layer, then the risk of short circuit is reduced, but the temperature of the rechargeable battery increases and the possibility of undesired ignition increases
Solution Approach 1:
The insulating layer is designed with spatially varying thickness: thicker at the edges (protruding beyond the active material layer) to prevent short circuits, and thinner at the center to reduce thermal resistance. This local differentiation allows the layer to simultaneously provide electrical insulation where needed while maintaining thermal conduction pathways to dissipate heat from the active material region.
Solution Approach 2:
The insulating layer extends in the horizontal dimension beyond the active material layer boundaries, creating an L-shaped cross-section profile. This dimensional extension allows the layer to perform dual functions: providing insulation at the edges where short circuits are most likely, while the reduced thickness in the vertical dimension at the center minimizes thermal resistance for heat dissipation.
2Productivity
If the rechargeable battery is quickly charged or the output is increased, then the productivity is improved, but a section where electric current is concentrated occurs and the temperature increases
Solution Approach 1:
The insulating layer acts as an intermediary thermal management component positioned between the active material layer and the current collector. It provides electrical insulation to prevent short circuits while its controlled thermal conductivity and geometric design create thermal pathways that mediate heat flow, preventing localized temperature buildup during high-rate charging operations.
3Quantity of substance
If the areas of the two different electrodes are different, then the electrode design is optimized for capacity, but the exposed substrate and active material layers contact each other causing short circuit
Solution Approach 1:
The insulating layer is pre-formed on the current collector substrate before the active material layer is applied, and it extends beyond the active material boundaries. This preliminary positioning ensures that when the electrodes are assembled with different areas, the insulating layer is already in place to prevent contact between the exposed substrate and opposing electrode, eliminating the short circuit risk before assembly occurs.
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 electrode assembly effectively reduces the risk of short circuits and heat-related issues, enhancing safety by managing electric current distribution and heat dissipation, thus preventing potential fires.
Implementation Method 1
a resistance of the functional layer may be greater than a resistance of the substrate and may be less than a resistance of the active material layer
Data Source
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AI summary
An electrode includes: a substrate including an electrode uncoated portion and an electrode active portion; a functional layer on the substrate; and an active material layer on the functional layer of the electrode active portion. The functional layer includes a first portion overlapping the electrode active portion and a second portion extending from the first portion to the electrode uncoated portion. The electrode is for a rechargeable battery.