Electrode Coating Gradients for Uniform Li-Ion Cell Aging
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Solution Overview
Problem
Lithium-ion battery cells, particularly cylindrical designs, experience non-uniform degradation due to induced temperature distributions during high-rate operations, leading to reduced capacity and accelerated aging.
Innovation Solution
Induce non-uniformities in electrode design characteristics such as porosity, thickness, and loading by controlling manufacturing processes like line speed, slurry flow rate, and calendaring pressure to counteract non-uniform electrochemical reaction rates, promoting a more uniform reaction rate and reducing fatigue and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-rate operation (DC fast charging) is performed, then charging speed and power are improved, but non-uniform temperature distribution is induced causing increased fatigue and degradation
Solution Approach 1:
The electrode coating is designed with spatially varying properties (porosity, thickness, loading) across different radial positions to compensate for the non-uniform temperature distribution. Regions with higher temperatures have different coating characteristics compared to cooler regions, ensuring uniform electrochemical reaction rates throughout the electrode during high-rate charging operations.
2Power
If non-uniform temperature distribution occurs, then heat generation is improved for power delivery, but electrochemical reaction rate non-uniformity increases causing capacity fade
Solution Approach 1:
The electrode coating parameters (porosity, thickness, loading) are deliberately varied across the radial direction to counteract the temperature non-uniformity. This parameter variation ensures that the product of temperature and coating properties results in relatively uniform electrochemical reaction rates, maintaining both power delivery capability and reaction uniformity during high-rate operation.
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
The method enhances battery performance by decreasing fatigue life and degradation, maintaining capacity during high-rate operations like DC fast charging.
Implementation Method 1
calculating an electrochemical reaction rate in the battery cell; determining at least one non-uniformity in the electrochemical reaction rate; inducing a non-uniformity in at least one electrode design characteristic to counteract the at least one non-uniformity in the electrochemical reaction rate
Data Source
AI summary
A method of reducing non-uniform degradation in a battery cell comprising: determining a likely temperature distribution for the battery cell; determining a temperature profile of the battery cell; calculating an electrochemical reaction rate in the battery cell; determining at least one non-uniformity in the electrochemical reaction rate; inducing a non-uniformity in at least one electrode design characteristic to counteract the at least one non-uniformity in the electrochemical reaction rate; and including at least one electrode having the non-uniformity in at least one electrode design characteristic in the battery cell to drive a more uniform electrochemical reaction rate through the battery cell, which could result in decreased fatigue life, particle stress and degradation of the battery cell during, for example, but not limited to high rate operation.