Battery Electrode Insulating Layer for Edge Short-Circuit Prevention
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Solution Overview
Problem
Existing lithium secondary batteries face issues with insulation between electrodes, leading to potential short circuits and reduced stability due to insufficient thermal resistance and irregular electrode edges, which can cause thermal runaway and capacity loss.
Innovation Solution
The electrode design includes an insulating layer overlapping the electrode active material layer in a partial region, with a controlled thickness ratio, and a simultaneous drying process to enhance cohesion and insulation, using a wet-on-wet coating method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is disposed between positive and negative electrodes to maintain electric insulation, then short circuit prevention is improved, but thermal resistance remains insufficient at about 120 to 160°C leading to thermal runaway
Solution Approach 1:
The patent applies composite materials by combining polyolefin resin with inorganic particles (such as alumina, silica, or boehmite) to create a separator that maintains the original electrical insulation properties while significantly improving thermal resistance. The inorganic particles form a heat-resistant framework that prevents separator shrinkage at temperatures above 160°C, thereby preventing thermal runaway while maintaining electric insulation functionality.
Solution Approach 2:
The patent changes the thermal parameter of the separator by incorporating inorganic particles with high melting points (alumina: 2050°C, silica: 1710°C, boehmite: 300°C). This parameter change allows the separator to maintain its structural integrity and dimensional stability at temperatures where conventional polyolefin separators would shrink and fail, thus resolving the thermal resistance limitation.
2Productivity
If electrodes are cut into constant size and stacked layer by layer to produce prismatic batteries, then manufacturing efficiency is improved, but irregular edges cause minute internal short circuits and reduced battery performance
Solution Approach 1:
The patent applies preliminary action by forming an insulating layer on the electrode edges before the stacking process. This insulating layer, created through wet-on-wet coating with controlled thickness ratio, prevents internal short circuits at the edges before they can occur during stacking, thereby maintaining both manufacturing efficiency and preventing defects.
Solution Approach 2:
The patent applies local quality by creating an insulating layer specifically at the edge regions of the electrodes where short circuits are most likely to occur. The thickness ratio control ensures that the insulating layer is sufficiently thick at edges to prevent short circuits while remaining thin enough in overlapping regions to avoid capacity loss, thus addressing the specific problem area without compromising overall electrode performance.
3Reliability
If insulation tape is wound around electrode tabs to prevent contact with upper electrode assembly, then short circuit prevention is improved, but device complexity and thickness increase
Solution Approach 1:
The patent extracts the insulation function from the separate insulation tape component and integrates it directly into the electrode structure through a permanently formed insulating layer. This eliminates the need for separate insulation tape winding operations, reducing device complexity while maintaining short circuit prevention functionality through the thickness-controlled insulating layer at critical areas.
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 design improves electrode insulation and cohesion, preventing short circuits and enhancing battery quality and stability by minimizing erosion and capacity reduction.
Implementation Method 1
improves electrode insulation and cohesion, preventing short circuits
Implementation Method 2
simultaneous drying process to enhance cohesion and insulation
Data Source
AI summary
The present invention provides an electrode for a lithium secondary battery, which includes an electrode current collector, an electrode active material layer formed on the electrode current collector, and an insulating layer formed on the electrode current collector and overlapping the electrode active material layer in a partial region. Here, when the thickness of the electrode active material layer in the region in which the electrode active material layer and insulating layer do not overlap is d1, and the thickness of the insulating layer in the region in which the electrode active material layer and insulating layer do not overlap is d2, d2/d1 is 0.02 to 0.4.