Battery Anode Void Structure for Micro Short Circuit Suppression
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Solution Overview
Problem
Chemically-occurring micro short circuits in non-aqueous electrolyte secondary batteries are a significant issue due to metal fragments trapped in the positive electrode, leading to metal ion migration and deposition, which can cause shorts between the electrodes.
Innovation Solution
Control the size, shape, and amount of voids in the negative electrode active material layer by using void-forming aids like microcapsules to create voids with specific dimensions and distribution, reducing the likelihood of metal deposition towards the positive electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voids are formed in the negative electrode active material layer to prevent metal deposition, then chemically-occurring micro short circuits are decreased, but the electrode structure becomes more complex
Solution Approach 1:
The negative electrode active material layer is designed with controlled voids (porosity) to provide spaces where metal ions can be deposited instead of forming direct contact between electrodes. The voids have specific characteristics: average equivalent circle diameter of 9.6-35.8 μm, average circularity of 0.26 or more, and area percentage of 3.1-30.9%. This porous structure fundamentally changes the electrode from a dense solid to a controlled porous medium that redirects metal deposition pathways.
Solution Approach 2:
The voids act as intermediary spaces between the negative electrode substrate and the positive electrode. Instead of metal ions traveling directly through the electrolyte to form conductive bridges between electrodes, they are diverted into the voids where they can be trapped. The voids serve as a mediating structure that intercepts and contains metal deposition, preventing direct electrode-to-electrode contact.
2Reliability
If the area percentage of voids is increased to better trap metal ions, then micro short circuit prevention improves, but the density of the negative electrode active material layer decreases
Solution Approach 1:
The invention optimizes multiple parameters of the voids simultaneously: size (average equivalent circle diameter: 9.6-35.8 μm), shape (average circularity: 0.26 or more), and quantity (area percentage: 3.1-30.9%). By carefully controlling these parameters, the design achieves effective metal ion trapping while minimizing the impact on overall electrode density. The specific range of 3.1-30.9% area percentage represents an optimized balance between void space for metal trapping and solid material for electrochemical function.
3Reliability
If voids with specific size and shape are created to optimize metal ion trapping, then deposition control improves, but manufacturing precision requirements increase
Solution Approach 1:
The use of porous materials (voids) with specifically controlled characteristics provides a robust mechanism for metal ion trapping. The voids' physical presence and specific dimensions (9.6-35.8 μm diameter, 0.26+ circularity) create predictable pathways and trapping zones that are less sensitive to minor manufacturing variations. The porous structure inherently provides tolerance for dimensional variations while maintaining functional effectiveness.
Solution Approach 2:
By defining specific parameter ranges rather than exact values, the invention creates a manufacturing-friendly specification. The void characteristics are specified as ranges (diameter: 9.6-35.8 μm, circularity: 0.26 or more, area percentage: 3.1-30.9%), which provides manufacturing tolerance while ensuring functional performance. This parametric approach allows for practical manufacturing while achieving reliable metal ion trapping.
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
Significantly decreases chemically-occurring micro short circuits by preventing metal deposition within the voids, thereby maintaining electrode integrity and reducing voltage drops.
Implementation Method 1
The metal ions thus generated are dissolved in the electrolyte solution. The metal ions migrate to the negative electrode.
Implementation Method 2
At the negative electrode, the metal ions are reduced to become solid, and then deposited.
Data Source
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AI summary
A non-aqueous electrolyte secondary battery comprises a positive electrode, a negative electrode, a separator, and an electrolyte solution. At least part of the separator is interposed between the positive electrode and the negative electrode. The negative electrode includes a negative electrode substrate and a negative electrode active material layer. The negative electrode active material layer is placed on a surface of the negative electrode substrate. Voids are formed in the negative electrode active material layer. In a cross section parallel to a thickness direction of the negative electrode active material layer, the voids have an average equivalent circle diameter from 9.6 µm to 35.8 µm, an average circularity of 0.26 or more, and an area percentage from 3.1% to 30.9%.