Layered Battery Electrode Structure for Stable Active Material Orientation
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Solution Overview
Problem
Existing electrode manufacturing processes for batteries often result in the orientation of active materials being disrupted during press work, leading to degraded rate performance.
Innovation Solution
The electrode design incorporates a negative electrode active material layer with a first region and a second region, where the active material and binder are distributed differently to maintain the orientation of high-aspect-ratio active materials and reduce stress during press work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active material is oriented in the negative electrode active material layer to improve rate performance, then ionic conduction is improved, but the state of orientation changes during press work
Solution Approach 1:
The negative electrode active material layer is divided into a first region (near the base material) and a second region (outer surface region). The first region contains high-aspect-ratio active material with binder to maintain orientation, while the second region contains low-aspect-ratio active material to provide cushioning during press work. This segmentation allows different regions to serve different functions, resolving the contradiction between maintaining orientation and withstanding press work.
Solution Approach 2:
Different regions of the negative electrode active material layer are given different properties: the first region has high-aspect-ratio active material and higher binder content for orientation stability, while the second region has low-aspect-ratio active material and lower binder content for cushioning. This local differentiation allows the electrode to simultaneously maintain orientation where needed and absorb press work stress where required.
2Stability of the object's composition
If binder is distributed throughout the negative electrode active material layer to fix active material orientation, then orientation stability is improved, but ionic conduction is inhibited
Solution Approach 1:
The binder distribution is segmented: the first region has higher binder content (area fraction B1) to stabilize active material orientation, while the second region has lower binder content (area fraction B2) to maintain ionic conduction pathways. This segmentation resolves the contradiction between using enough binder to fix orientation and using too little binder to allow ionic conduction.
Solution Approach 2:
The binder concentration is locally optimized: higher binder concentration in the first region provides orientation stability where the high-aspect-ratio active material needs support, while lower binder concentration in the second region preserves ionic conduction channels. This local quality differentiation simultaneously achieves both orientation stability and ionic conduction.
Data Source
AI summary
An electrode for a battery comprises a base material and a negative electrode active material layer. A cross section of the negative electrode active material layer parallel to a thickness direction includes a first region and a second region. In the thickness direction, the first region is interposed between the second region and the base material. The first region includes a first active material and a first binder. The second region includes a second active material and a second binder. Either a set of relationships of “A2<A1” and “B2<B1” or a set of relationships of expressions “A2>A1” and “B2>B1” is satisfied. A1 represents an aspect ratio of the first active material. A2 represents an aspect ratio of the second active material. B1 represents an area fraction of the first binder in the first region. B2 represents an area fraction of the second binder in the second region.