Battery Cell Electrode Capacity Layout for Matched Fading Rates
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Solution Overview
Problem
Capacity fading in battery cells is accelerated due to uneven active lithium loss across different electrode assemblies, particularly those closer to the middle of the housing experiencing higher operating temperatures and intensified side reactions.
Innovation Solution
The battery cell design includes a housing with a cavity divided into regions, where the capacity of electrode assemblies in the second region is greater than those in the first region, ensuring a matched fading rate and reducing current density and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode assemblies are uniformly distributed in the housing, then the structure is simple and easy to manufacture, but the temperature distribution becomes uneven causing accelerated capacity fading in the middle region
Solution Approach 1:
The patent applies local quality by differentiating the capacity of electrode assemblies based on their position in the housing. Middle electrode assemblies have higher capacity than end electrode assemblies, creating non-uniform local properties that compensate for the uneven temperature distribution and side reaction intensity across different regions of the battery cell.
2Reliability
If electrode assemblies are arranged with higher capacity in the middle region, then the fading rate is matched across regions, but the device complexity increases due to non-uniform capacity distribution
Solution Approach 1:
The patent changes the capacity parameter of electrode assemblies based on their spatial position. By adjusting the capacity values (Cap1 for end regions, Cap2 for middle region where Cap2 > Cap1), the system compensates for position-dependent degradation effects, achieving uniform fading rates across all electrode assemblies despite their different thermal environments.
3Ease of manufacture
If all electrode assemblies have the same capacity, then the manufacturing process is simplified, but the current density becomes uneven leading to excessive heat generation in the middle region
Solution Approach 1:
The patent implements local quality by assigning different capacity values to electrode assemblies in different spatial regions. The middle electrode assemblies have higher capacity (Cap2) compared to end electrode assemblies (Cap1), which locally adjusts the current density distribution to reduce heat generation in the thermally sensitive middle region while maintaining manufacturing feasibility.
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 design slows down overall capacity fading and increases the service life of the battery cell by matching the fading rates of electrode assemblies and reducing temperature differences and heat generation.
Implementation Method 1
an equivalent rate of the electrode assembly in the second region is lower during charge and discharge, that is, the current density is lower, and the resulting heat is lower, thereby further reducing the temperature difference between the electrode assembly in the first region and the electrode assembly in the second region
Implementation Method 2
the side reaction at an electrode interface of the electrode assembly in the second region is intenser. Consequently, the loss of active lithium in the electrode assembly in the second region is heavier, and the capacity fading is faster
Data Source
AI summary
A battery cell, a battery, and an electrical device are disclosed. The battery cell includes a housing and at least 3 electrode assemblies. A cavity is defined in the housing. The cavity includes a first region and a second region. The first region is closer to the housing than the second region. The at least 3 electrode assemblies are disposed in the cavity. A capacity of a single electrode assembly located in the first region is Cap1, a capacity of a single electrode assembly located in the second region is Cap2, and Cap2 is greater than Cap1. By controlling Cap2 to be greater than Cap1, the electrode assembly in the second region contains more active lithium than the electrode assembly in the first region.