Lithium Ion Battery Electrode Design for Metal Deposition Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries face issues with reliability and capacity due to metal lithium deposition at the border parts between electrode active material applied and non-applied regions, leading to reduced performance and durability.
Innovation Solution
A lithium ion secondary battery element design featuring a positive electrode with a positive electrode active material layer that includes both a flat and a thin part, with an insulating member covering parts of the thin and non-applied regions, and a negative electrode with a similar structure, where the charging capacity ratios between these regions are optimized to prevent metal lithium deposition and enhance battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode active material is applied more thickly to increase battery capacity, then the battery capacity increases, but metal lithium deposition occurs more frequently at the border part between the electrode active material applied part and non-applied part
Solution Approach 1:
The positive electrode active material layer is divided into two distinct regions: a flat part with uniform thickness and a thin part with gradually decreasing thickness toward the border. This segmentation allows the thin part to reduce lithium ion flux at the border region, preventing metal lithium deposition while the flat part maintains high capacity
Solution Approach 2:
Different regions of the positive electrode active material layer are given different thickness characteristics to serve different functions. The flat part provides high capacity in the central region, while the thin part suppresses lithium deposition at the border region. This local differentiation resolves the contradiction between capacity and reliability
2Reliability
If the charging capacity ratio A/C is increased at the outer edge part to prevent metal lithium deposition, then metal lithium deposition is suppressed, but the overall battery capacity is reduced
Solution Approach 1:
The charging capacity ratio is optimized differently for different regions: at the outer edge part, the ratio A E /C E is set to 1.10-1.34 to suppress lithium deposition, while at the central part, the ratio A C /C C is set to 1.03-1.08 to maximize capacity. This local optimization resolves the contradiction between reliability and capacity
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A lithium ion secondary battery element includes: a positive electrode that includes a positive electrode current collector including a positive electrode active material applied part where a positive electrode active material is applied to form a positive electrode active material layer, and including a positive electrode active material non-applied part where the positive electrode active material is not applied, the positive electrode active material layer including a positive electrode active material layer flat part and a positive electrode active material layer thin part that is thinner than the positive electrode active material layer flat part, and the positive electrode further including an insulating member that covers at least a part of the positive electrode active material layer thin part and at least a part of the positive electrode active material non-applied part; a separator; and a negative electrode that includes a negative electrode current collector including a negative electrode active material applied part where a negative electrode active material is applied to form a negative electrode active material layer, and including a negative electrode active material non-applied part where the negative electrode active material is not applied, wherein: the positive electrode, the separator, and the negative electrode are stacked in this order; and the positive electrode active material non-applied part and the negative electrode active material non-applied part face each other through the separator.