Dual-Density Negative Electrode Layout for Battery Capacity and Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face a challenge in increasing capacity while maintaining input-output properties, as higher electrode coating weights can lead to longer ion-diffusion pathways and degradation of performance.
Innovation Solution
A negative electrode with a dual-density active material layer, comprising a first high-density region and a second low-density region, where the density of the second region is at least 7% less than the first region, and the volume ratio of the second region is between 7% and 50%, with a grid or columnar structure and a shortest distance of 50 µm or less between second regions, to optimize ion diffusion and prevent performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the coating weight of the negative electrode active material layer is increased to enhance capacity, then the battery capacity increases, but the ion-diffusion pathways become longer and input-output properties are degraded
Solution Approach 1:
The negative electrode active material layer is designed with spatially varying density: a first region with higher density (2.4-2.8 g/cm³) and a second region with lower density (2.0-2.4 g/cm³). This local quality variation allows the high-density region to provide high capacity while the low-density region maintains short ion-diffusion pathways, thus resolving the contradiction between capacity and input-output properties
Solution Approach 2:
The negative electrode active material layer is segmented into two distinct regions with different density characteristics. The first region (higher density) and second region (lower density) are distributed throughout the layer, creating a heterogeneous structure that simultaneously achieves high capacity storage and efficient ion transport
2Quantity of substance
If the negative electrode active material layer is formed solely of a high density region, then capacity can be increased, but ion-diffusion pathways become long causing degradation of input-output properties
Solution Approach 1:
By creating local low-density regions within the high-density matrix, the patent provides localized pathways for rapid ion diffusion while maintaining overall high capacity. The low-density second region acts as an ion-transport highway that reduces the effective diffusion length
3Power
If the negative electrode active material layer is formed solely of a low density region, then input-output properties can be enhanced, but it becomes difficult to enhance capacity
Solution Approach 1:
The patent segments the electrode layer into functional zones: low-density regions optimized for ion transport and high-density regions optimized for capacity. This segmentation allows each region to perform its specialized function, achieving both high power and high capacity
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 configuration enhances the capacity of the battery while maintaining or improving input-output properties by ensuring shorter ion-diffusion pathways and efficient ion movement, as demonstrated by higher CC charging ratios in test batteries with optimal volume ratios and shortest distances between second regions.
Implementation Method 1
ion-diffusion pathways for lithium ions and the like included in the electrolyte solution may become longer
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A negative electrode (10) comprising a negative electrode current collector (11) and a negative electrode active material layer (12) including a negative electrode active material, wherein the negative electrode active material layer (12) includes a first region (13) and a second region (14), a density of the second region (14) is at least 7% less than a density of the first region (13), and a volume ratio of the second region (14) to the negative electrode active material layer (12) is more than 7% and not more than 50%.