Segmented Negative Electrode Film Layer for Silicon Battery Cycling
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving high energy density while maintaining good rate performance and cycling performance.
Innovation Solution
The secondary battery incorporates a negative electrode plate with a specific structure, comprising a negative electrode current collector and a negative electrode film layer. This film layer is divided into two regions: the first region contains a first active material with a high proportion of primary carbon-based particles, and the second region contains a second active material with a high proportion of secondary carbon-based particles. This configuration optimizes ion and electron transport, enhancing both rate and cycling performance while maintaining high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode film layer uses a uniform composition throughout, then the manufacturing process is simple, but the rate performance and cycling performance cannot be optimized while maintaining high energy density
Solution Approach 1:
The negative electrode film layer is divided into a first region (near the current collector) and a second region (farther from the current collector), with each region having different active material compositions. This segmentation allows optimization of ion transport and electron transport in different zones, improving both rate performance and cycling performance while maintaining high energy density.
Solution Approach 2:
Different regions of the negative electrode film layer are assigned different material compositions: the first region contains active material optimized for electron transport and structural stability, while the second region contains active material optimized for ion transport and capacity. This local quality differentiation enables each region to perform its specific function optimally, resolving the contradiction between reliability and device complexity.
2Quantity of substance
If the negative electrode uses high proportion of silicon-based material for high energy density, then the energy density increases, but the cycling performance deteriorates due to volume expansion
Solution Approach 1:
Silicon-based material is concentrated in the second region where it can contribute to high energy density, while the first region near the current collector uses carbon-based material with excellent structural stability. This local quality differentiation allows the silicon-based material to deliver high capacity without suffering from volume expansion issues, as it is positioned away from the current collector where expansion would cause most damage.
Solution Approach 2:
The negative electrode film layer uses a composite structure combining carbon-based material and silicon-based material in different regions. The carbon-based material in the first region provides structural stability and electron conductivity, while the silicon-based material in the second region provides high capacity. This composite material approach enables the battery to achieve high energy density while maintaining good cycling performance.
3Quantity of substance
If the negative electrode film layer has high compacted density for high energy density, then the energy density increases, but the ion transport performance deteriorates
Solution Approach 1:
The first region near the current collector is designed with higher compacted density to ensure good electron transport and structural stability, while the second region farther from the current collector is designed with lower compacted density to facilitate ion transport. This local quality differentiation in density allows the battery to achieve high overall energy density while maintaining excellent ion transport performance in the region where ions are actively transported.
Data Source
AI summary
A secondary battery and an electric apparatus are disclosed. The secondary battery includes a negative electrode plate including a negative electrode current collector and a negative electrode film layer with a thickness of H; a first surface away from the negative electrode current collector; and a second surface opposite the first surface. A first region of the negative electrode film layer includes a first active material with a thickness range from the second surface of the negative electrode film layer to 0.3H. The first active material includes a first carbon-based material and a first silicon-based material. The first carbon-based material includes primary particles. The first silicon-based material includes secondary particles formed by aggregating the primary particles. A second region of the negative electrode film layer includes a second active material and has a thickness range from the first surface of the negative electrode film layer to 0.3H.