Wound Nonaqueous Battery Electrodes for High-Rate Deterioration Control
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries experience high-rate deterioration due to the long moving path of the electrolytic solution, leading to salt concentration unevenness and increased resistance, particularly in large-size batteries with extended electrode widths.
Innovation Solution
A nonaqueous electrolyte secondary battery design with a wound electrode body configuration where the negative electrode active material layer has a length of 200 mm or more, an infiltration speed of 0.02 μL/s to 0.05 μL/s, and a distance of 0 mm to 5 mm between the positive and negative electrode active material layers, ensuring a nonaqueous electrolyte solution ratio of 130% or less in the fully charged state, which helps in reducing high-rate deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the electrode width is increased to create large-size batteries, then the battery capacity is improved, but the moving path of the electrolytic solution becomes long causing high-rate deterioration
Solution Approach 1:
The battery is divided into multiple battery modules, each with its own wound electrode body. The electrolytic solution moves independently within each compact module rather than traversing the entire large battery, effectively segmenting the long moving path into shorter segments while maintaining high capacity through parallel module configuration.
Solution Approach 2:
The electrode body uses a wound configuration that transforms the two-dimensional electrode layout into a three-dimensional compact structure. This winding arrangement reduces the electrolytic solution's moving path length by creating multiple overlapping active material layers, allowing the solution to access different electrode regions through vertical movement rather than horizontal traversal.
2Volume of stationary object
If the moving path of the electrolytic solution is long, then the battery size can be large, but salt concentration unevenness increases leading to high-rate deterioration
Solution Approach 1:
By dividing the battery into multiple modules with compact electrode bodies, the electrolytic solution's travel distance in each module is limited. This segmentation prevents excessive salt concentration depletion that would occur in a single large battery, maintaining more uniform salt distribution across all electrode regions.
Solution Approach 2:
The wound electrode body configuration creates dynamic electrolyte distribution pathways where the electrolytic solution can efficiently penetrate multiple electrode layers through the winding structure. This dynamic arrangement ensures better salt concentration uniformity compared to flat electrode configurations.
3Quantity of substance
If the moving path of the electrolytic solution is long, then the battery can accommodate more active material, but resistance increases causing high-rate deterioration
Solution Approach 1:
The battery is segmented into multiple modules, each with compact electrode bodies that minimize electrolytic solution resistance. By distributing the active material across multiple modules rather than one large battery, the total resistance is reduced while maintaining equivalent or higher capacity through parallel connection of modules.
Solution Approach 2:
The wound electrode configuration utilizes three-dimensional space efficiently, creating multiple active material layers that are vertically stacked through winding. This allows the electrolytic solution to access large quantities of active material through short vertical paths rather than long horizontal paths, reducing resistance while accommodating more active material.
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 effectively suppresses high-rate deterioration by minimizing salt concentration unevenness and maintaining optimal electrolyte distribution, enhancing the battery's high-rate characteristics and cycle performance.
Implementation Method 1
an infiltration speed of the nonaqueous electrolytic solution in the negative electrode active material layer is 0.02 μL/s or more and 0.05 μL/s or less
Data Source
AI summary
In a nonaqueous electrolyte secondary battery disclosed herein, a length of a negative electrode active material layer in a winding axis direction of a wound electrode body is 200 mm or more, an infiltration speed of a nonaqueous electrolytic solution in the negative electrode active material layer is 0.02 μL/s to 0.05 μL/s, a distance between an end portion of a positive electrode active material layer and an end portion of the negative electrode active material layer is more than 0 mm and 5 mm or less in the winding axis direction, and, in a fully charged state, a ratio of the nonaqueous electrolytic solution to a total void volume of the positive electrode active layer and the negative electrode active layer in the wound electrode body is 130% or less.