Electrode Assembly Loading Gradient to Limit Lithium Plating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing secondary batteries face challenges in maintaining an optimal capacity ratio between the negative and positive electrodes, leading to unnecessary increases in negative electrode capacity and lithium precipitation during winding, which affects the battery's output efficiency.
Innovation Solution
The electrode assembly design includes specific loading levels and patterns for positive and negative electrode coating layers, with varying loading levels and non-coating portions to maintain a minimum capacity ratio and minimize lithium precipitation, optimizing the electrode assembly's capacity and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the loading level of positive electrode coating layers is increased uniformly, then the capacity of the positive electrode is improved, but the capacity ratio between negative and positive electrodes becomes unbalanced and lithium precipitation occurs
Solution Approach 1:
The patent applies local quality by differentiating the loading levels of positive electrode coating layers into four distinct regions (first through fourth layers) with progressively decreasing loading levels. The first positive electrode coating layer has the highest loading level, while the fourth has the lowest, creating a gradient distribution that locally optimizes capacity while maintaining overall balance with the negative electrode.
Solution Approach 2:
The patent segments the positive electrode coating into four separate layers with different loading levels rather than using a uniform coating. This segmentation allows each layer to contribute differently to the overall capacity, enabling precise control over the capacity ratio and preventing lithium precipitation by distributing the electrochemical load across multiple zones.
2Quantity of substance
If the loading level of negative electrode coating layer is increased to match positive electrode capacity, then the energy density is improved, but lithium precipitation occurs during winding
Solution Approach 1:
The patent applies preliminary anti-action by pre-adjusting the loading levels of positive electrode coating layers to create a capacity buffer before assembly and winding. The differentiated loading levels (first layer highest, fourth layer lowest) are designed in advance to compensate for capacity imbalances that would otherwise occur during winding, preventing lithium precipitation before it can happen.
Solution Approach 2:
The patent changes the loading level parameter of positive electrode coating layers across different regions, creating a gradient from high to low loading levels. This parameter variation allows the positive electrode to maintain an appropriate capacity ratio with the negative electrode, enabling high energy density while preventing lithium precipitation through optimized electrochemical balance.
3Power
If the capacity ratio of negative to positive electrode is increased to maximize output, then the output capacity is improved, but lithium precipitation occurs
Solution Approach 1:
The patent applies local quality by creating four distinct loading level zones in the positive electrode coating, where each zone (first through fourth layers) has a specific loading level optimized for its location. This local differentiation allows the positive electrode to maintain appropriate capacity ratios across different regions, maximizing output capacity while distributing the electrochemical stress to prevent lithium precipitation.
Solution Approach 2:
The patent introduces dynamics by creating a gradient structure in the positive electrode coating layers, where the loading levels vary systematically from the first layer (highest) to the fourth layer (lowest). This dynamic distribution of loading levels allows the electrode to adapt to different operational conditions and maintains optimal capacity ratios that maximize power output while preventing lithium precipitation.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The present invention relates to an electrode assembly and a secondary battery comprising same, wherein by adjusting at least one of a loading level of a positive electrode coating layer and a loading level of a negative electrode coating layer, the negative electrode coating layer can be prevented from unnecessarily increasing in capacity, and a minimum capacity ratio of a positive electrode versus a negative electrode can be maintained in order to minimize lithium precipitation according to the number of winding turns of an electrode assembly.