Wound Li-Ion Electrode Geometry for Uniform Low-Temperature Discharge
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Solution Overview
Problem
Conventional lithium ion batteries with winding-type electrode assemblies face challenges in improving energy density due to the large space occupied by current collection components, leading to uneven lithium ion reactions and potential overdischarge issues, especially at low temperatures.
Innovation Solution
A wound electrode assembly with lithium manganese oxide as the main positive active material, featuring a mixture layer forming portion and a non-forming portion at one or both ends, optimized to reduce the ratio of dimensions for improved space efficiency and reaction uniformity, allowing for enhanced energy density and reduced overdischarge risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a winding-type electrode assembly is used, then manufacturing cost is reduced and ease of manufacture is improved, but energy density deteriorates due to large space occupied by current collection components
Solution Approach 1:
The patent changes the geometric parameters of the electrode assembly by controlling the ratio of the first dimension (parallel to winding axis) to the second dimension (orthogonal to winding axis) to be 1.45 or more. This parameter optimization reduces the space occupied by current collection components while maintaining the winding structure, thereby improving energy density without sacrificing ease of manufacture
Solution Approach 2:
The patent optimizes the dimensional ratio along the winding axis direction, utilizing the longitudinal dimension more effectively. By making the first dimension (along winding axis) at least 1.45 times the second dimension, the design redistributes space utilization across dimensions to minimize current collector volume while preserving the manufacturable winding configuration
2Device complexity
If a winding-type electrode assembly is used, then manufacturing simplicity is improved, but reaction uniformity deteriorates leading to overdischarge issues
Solution Approach 1:
The patent addresses reaction uniformity by optimizing the dimensional ratio parameter (first dimension/second dimension ≥ 1.45), which improves lithium ion distribution uniformity across the electrode assembly during charge-discharge cycles, preventing localized overdischarge while maintaining the simple winding structure
Solution Approach 2:
The patent applies local quality improvement by ensuring uniform lithium ion reaction characteristics across different regions of the electrode assembly through the optimized dimensional ratio. This creates more homogeneous local reaction conditions throughout the assembly, preventing localized degradation while preserving overall structural simplicity
Data Source
AI summary
An energy storage device includes a wound electrode assembly containing lithium manganese oxide as a main component in a positive active material, and a case that houses the wound electrode assembly. The wound electrode assembly includes a mixture layer forming portion in which a mixture layer is formed, and a mixture layer non-forming portion located at least at one end in a first direction parallel to a winding axis. In the wound electrode assembly, a ratio of a dimension in the first direction to a dimension in a second direction orthogonal to the first direction in plan view is 1.45 or more.