Battery Electrode Sheet Insulation for Burr-Induced Short Circuits
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Solution Overview
Problem
Existing electrode sheet designs in battery cells face issues with reliability due to burrs and exposed end faces causing short circuits and lapping with opposite polarity electrodes during the cutting process, leading to reduced performance.
Innovation Solution
An electrode sheet design incorporating a current collector with a specific insulating layer structure, utilizing a thermoplastic polymer with controlled particle size distribution and melting point, which forms a uniform and dense covering on the end face and burrs during cutting to prevent lapping and short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cutting process is used to cut the tab from the current collector, then the cutting process is simple and fast, but burrs are generated and the end face is exposed, causing lapping and short circuits with opposite polarity electrodes
Solution Approach 1:
The patent applies preliminary action by pre-coating the current collector with an insulating layer containing thermoplastic polymer particles before the cutting process. This pre-prepared insulating layer is positioned to cover the end face and burrs that will be generated during cutting, preventing lapping and short circuits before they can occur. The thermoplastic polymer is selected with specific melting point and particle size characteristics to ensure it will effectively seal the exposed areas during the subsequent cutting operation.
Solution Approach 2:
The patent uses the thermoplastic polymer insulating layer as an intermediary substance between the current collector and the opposite polarity electrode. This intermediary layer physically separates and insulates the exposed end face and burrs from the electrode, preventing direct contact that would cause short circuits. The insulating layer acts as a protective mediator that eliminates the harmful interaction between the current collector and the electrode.
2Manufacturing precision
If the thermoplastic polymer particle size is not properly controlled, then the insulating layer may be simple to manufacture, but the insulating layer becomes non-uniform and non-dense, reducing its effectiveness
Solution Approach 1:
The patent applies parameter changes by specifying precise ranges for the thermoplastic polymer particle size (volume-weighted average diameter of 6-10 μm and maximum particle size of 90-110 μm) and melting point (80-250°C). These controlled parameters ensure that the polymer particles pack uniformly in the insulating layer and melt at appropriate temperatures during cutting to form a dense, continuous protective layer. The controlled particle size distribution prevents agglomeration and ensures uniform distribution throughout the insulating layer.
Solution Approach 2:
The patent utilizes phase transitions of the thermoplastic polymer to achieve uniform and dense insulating layer formation. The polymer particles are selected with a melting point range of 80-250°C, allowing them to transition from solid to liquid state during the cutting process when heated by friction or external heating. This phase transition enables the polymer to flow and fill gaps between particles, creating a dense, continuous insulating layer that effectively seals the end face and burrs. After cooling, the polymer solidifies to maintain the dense structure.
3Reliability
If the insulating layer does not cover the end face properly, then the structure is simpler, but the exposed current collector causes lapping with the electrode
Solution Approach 1:
The patent applies local quality by concentrating the insulating layer material specifically at critical areas where lapping occurs - the end face and burrs of the current collector. The insulating layer is not uniformly distributed across the entire current collector surface but is strategically positioned where it is most needed for prevention of short circuits. This localized application of insulation provides effective protection while minimizing unnecessary material usage and structural complexity.
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 solution enhances the reliability of battery cells by reducing the risk of short circuits and improving the uniformity and density of the insulating layer, thereby enhancing the overall performance and safety of the battery.
Implementation Method 1
the thermoplastic polymer in the second insulating layer on the surface of the transition region changes from a solid state to a flowing state after being heated. The thermoplastic polymer in the flowing state flows to the end face of the first end, and solidifies at the end face after being cooled
Implementation Method 2
the thermoplastic polymer changes from a solid state to a flowing state after being heated. The thermoplastic polymer in the flowing state flows to the end face of the first end, and solidifies at the end face after being cooled
Data Source
AI summary
An electrode sheet, a preparation method, a battery cell, a battery, and an electric device are provided. The electrode sheet includes a current collector having a main body and a tab extending from a first end of the main body in a first direction. The main body includes a coated region and a transition region located between the coated region and the tab. An active material layer is formed on the coated region. A first insulating layer is disposed on the end face of the first end. A second insulating layer is at least partially disposed on the surface of the transition region and includes a thermoplastic polymer. The thermoplastic polymer has a volumetric particle size distribution DV50 of 6-10 μm and a maximum particle size Dmax of 90-110 μm. The electrode sheet improves the reliability of the battery cell.