Secondary Battery Insulator Thickness Variation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary battery designs face challenges in preventing short circuits between positive and negative electrodes, leading to increased volume and deformation, which compromises energy density and reliability due to the use of insulators that disrupt uniform pressure application.
Innovation Solution
The battery design features a stacked configuration with insulators positioned on inclined or stepped portions of the electrodes, ensuring that the insulators do not increase the overall thickness, allowing for uniform pressure application and maintaining high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulators are arranged to cover boundaries between coated and uncoated portions in a stacked type secondary battery, then short circuit prevention is improved, but the thickness of the battery electrode assembly increases at those positions
Solution Approach 1:
The insulator is designed with non-uniform thickness, having a first thickness at the boundary between coated and uncoated portions and a second thickness at other positions, where the second thickness is smaller than the first thickness. This local variation in thickness provides sufficient insulation where needed while minimizing overall volume increase.
Solution Approach 2:
The insulator's thickness parameter is changed across different positions - thicker at the critical boundary region for short circuit prevention and thinner at other regions to reduce volume. This parameter optimization resolves the contradiction between reliability and volume.
2Reliability
If insulators with uniform thickness are used to cover electrode boundaries, then short circuit prevention is improved, but uniform pressure application deteriorates due to thickness differences
Solution Approach 1:
The insulator exhibits local quality variation in thickness - thicker where insulation is critical and thinner elsewhere. This design maintains sufficient insulation performance while ensuring that the overall thickness variation across the electrode assembly remains within acceptable limits for uniform pressure application.
Solution Approach 2:
By changing the thickness parameter of the insulator across different positions, the invention achieves both adequate short circuit prevention and maintains uniform pressure distribution. The thickness transitions from a first value at boundaries to a second value elsewhere, optimizing both reliability and stability.
3Reliability
If insulators are added to prevent short circuits, then safety is improved, but energy density decreases due to increased volume
Solution Approach 1:
The insulator's thickness parameter is optimized to have a first thickness at boundary regions and a second thickness elsewhere, where the second thickness is smaller. This parameter optimization provides necessary safety insulation while minimizing the volume occupied by the insulator, thereby preserving energy density.
Solution Approach 2:
The insulator is designed with non-uniform thickness distribution, providing sufficient thickness where safety is critical (at boundaries) and reduced thickness elsewhere. This local quality approach ensures safety requirements are met while minimizing overall volume impact on energy density.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6b
AI summary
A secondary battery includes a battery electrode assembly in which positive electrode 1 and negative electrode 6 are stacked alternately with separator 20 interposed therebetween. Positive electrode 1 and negative electrode 6 each have current collector 3, 8 and active material 2, 7. Each surface of current collectors 3, 8 has a coated portion and an uncoated portion of active materials 2, 8. Active material 2, 7 has inclined portions 2a, 7a having decreasing thickness. Insulators 40 are arranged to cover boundaries 4a between the coated portion and the uncoated portion of positive electrode 1. One or both of insulators 40 on both surfaces of positive electrode current collector 3 have one end 40a which is located on inclined surface 2a and which is opposite to inclined portion 7a of one or both of active materials 7 on both surfaces of negative electrode current collector 3, and have other end 40b which is located on uncoated portion of positive electrode 1.