Diverse Electrode Cell Stack Layout for Uniform Current Distribution
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Solution Overview
Problem
Conventional electrochemical cell stacks, such as lithium-ion batteries, face challenges in achieving uniform current distribution due to varying operating conditions across different cells, leading to non-uniform reaction rates and pressure differences, which can affect the performance and longevity of energy-intensive devices like electric vehicles.
Innovation Solution
The electrochemical cell stack incorporates inner and outer cells with electrodes of different compositions, loadings, thicknesses, and separators, allowing for non-uniform current distribution to accommodate varying operating conditions, with the inner cells having thinner electrodes and lower loadings to handle higher temperatures and pressures, while outer cells have thicker electrodes and higher loadings for lower conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional electrochemical cell stacks use uniform electrodes and separators in all cells, then manufacturing is simpler, but current distribution becomes non-uniform due to varying operating conditions
Solution Approach 1:
The patent applies local quality by making inner cells have different electrode compositions, loadings, and separator specifications compared to outer cells. Specifically, inner cells use electrodes with lower loading (e.g., 1-20% lower) and thinner separators to accommodate higher temperatures and pressures in the stack center, while outer cells use standard specifications. This localized differentiation optimizes current distribution across the stack.
Solution Approach 2:
The patent changes physical parameters of electrodes and separators based on position within the stack. Inner cells have electrodes with reduced loading (1-20% lower than outer cells) and thinner separators (e.g., 1-10% thinner), while outer cells maintain standard electrode loading and separator thickness. These parameter changes compensate for the harsher operating conditions in inner cells and achieve more uniform current distribution.
2Reliability
If inner cells use thinner electrodes and lower loadings to handle higher temperatures and pressures, then current distribution improves, but manufacturing complexity increases
Solution Approach 1:
The patent segments the electrochemical stack into distinct inner and outer cell regions with different specifications. The stack is divided such that central cells (inner cells) have one set of parameters (thinner electrodes, lower loading, thinner separators) while peripheral cells (outer cells) have another set (standard parameters). This segmentation allows each region to be optimized for its specific operating conditions.
Solution Approach 2:
The patent implements local quality by assigning different electrode and separator specifications to different spatial locations within the stack. Inner cells at the hot, high-pressure center use thinner electrodes with 1-20% lower loading and thinner separators, while outer cells at cooler locations use standard specifications. This localized differentiation resolves the complexity issue by creating a systematic, position-based design rule.
3Quantity of substance
If outer cells have thicker electrodes and higher loadings for lower temperature conditions, then energy storage capacity increases, but stress on inner cells increases
Solution Approach 1:
The patent changes electrode loading and separator thickness parameters based on position to balance energy storage and stress distribution. Outer cells use higher electrode loading (1-20% more than inner cells) and standard separator thickness to maximize energy storage in cooler regions. Inner cells use reduced loading (1-20% less) and thinner separators (1-10% thinner) to reduce stress and improve current distribution in high-temperature, high-pressure regions.
Solution Approach 2:
The patent applies local quality by optimizing electrode and separator specifications for local operating conditions. Outer cells with lower temperatures can accommodate higher electrode loading (1-20% more) and standard separator thickness for maximum energy storage. Inner cells with higher temperatures and pressures use reduced loading (1-20% less) and thinner separators (1-10% thinner) to manage thermal and mechanical stress, achieving a balance between energy storage and stress distribution.
Data Source
AI summary
Electrochemical stacks such as lithium-ion battery stacks and methods of assembling the same are disclosed. The stacks may include various electrochemical cells having different attributes. In one variation, the outer electrochemical cells may be different than the inner electrochemical cells. For example, the electrodes of the outer cells and inner cells may have different compositions, loading levels, and/or thicknesses. In a refinement, the separators of the outer cells and inner cells may have different thicknesses or porosities.