Battery Electrode Functional Layer for Short-Circuit Heat Control
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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 using materials with low thermal conductivity for insulation.
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 a specific active material composition to prevent short circuits and heat buildup, including a lithium iron phosphate compound and a sacrificial positive electrode material to enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If materials with low thermal conductivity are used as insulating layers to prevent short circuits, then electrical insulation is improved, but heat dissipation deteriorates causing temperature increase and ignition risk
Solution Approach 1:
The insulating layer is designed with spatially varying properties: the first insulating layer with lower thermal conductivity is positioned at the electrode uncoated portion where electrical insulation is critical, while the second insulating layer with higher thermal conductivity is positioned at the electrode active portion where heat dissipation is needed during charge/discharge operations
Solution Approach 2:
The insulating structure uses a composite configuration of two different insulating layers with distinct thermal conductivity characteristics, combining the electrical insulation benefits of low thermal conductivity materials with the heat dissipation benefits of high thermal conductivity materials in different spatial zones
2Reliability
If the area of the uncoated portion is increased to prevent short circuits, then electrical safety is improved, but the battery capacity is reduced
Solution Approach 1:
The insulating function is localized to specific regions through the dual-layer configuration, allowing the uncoated portion area to be minimized for capacity while maintaining electrical safety through targeted insulation at the electrode uncoated portion where short circuit risk exists
3Reliability
If the functional layer resistance is increased to prevent short circuits, then electrical insulation is improved, but current flow is restricted affecting battery performance
Solution Approach 1:
The functional layer resistance is spatially differentiated: the first functional layer at the electrode uncoated portion has higher resistance for electrical insulation, while the second functional layer at the electrode active portion has lower resistance to maintain current flow and power output during normal battery operation
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, ensuring safer operation and prolonged battery lifespan without significantly reducing capacity.
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
Implementation Method 2
materials with relatively low thermal conductivity may be utilized as the insulating layer... a temperature of the rechargeable battery may increase
Data Source
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.