Asymmetric Electrode Assembly for Lithium Dendrite Suppression
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Solution Overview
Problem
Lithium-ion batteries face safety issues due to lithium dendrite formation on electrode surfaces, leading to electrochemical short circuits, which are not effectively addressed by existing technologies.
Innovation Solution
The electrochemical device features a unique electrode assembly with a negative electrode plate and positive electrode plate configuration, where the capacity per unit area of the first negative active material layer is greater than the first positive active material layer, reducing the risk of lithium plating and dendrite formation by optimizing the distribution and specific capacities of active materials on the electrode collectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode plate configuration is used, then manufacturing simplicity is maintained, but lithium dendrite formation occurs leading to safety issues
Solution Approach 1:
The negative electrode plate is segmented into multiple regions with different active material layer configurations. Specifically, it includes a first region with a first negative active material layer, a second region with a second negative active material layer, and a third region with a third negative active material layer. This segmentation allows different regions to have different capacity characteristics, preventing uniform lithium dendrite formation across the entire electrode surface while maintaining overall battery safety.
Solution Approach 2:
Different regions of the negative electrode plate are assigned different local qualities through varying active material layer configurations. The first region has a first capacity per unit area, the second region has a second capacity per unit area, and the third region has a third capacity per unit area, where the second capacity is greater than both the first and third capacities. This local quality variation creates preferential sites for lithium ion insertion that prevent dendrite propagation, thereby improving battery safety without requiring complete structural redesign.
2Reliability
If uniform capacity distribution is used, then manufacturing simplicity is maintained, but lithium plating occurs on electrode surface
Solution Approach 1:
The negative active material layers are configured with different capacity per unit area values in different regions. The second negative active material layer has a greater capacity per unit area than the first and third negative active material layers. This local quality variation ensures that lithium ions are preferentially inserted into the second region during charging, preventing lithium plating on the electrode surface by providing adequate intercalation sites in high-risk areas.
Solution Approach 2:
The capacity per unit area parameter is changed across different regions of the negative electrode plate. By making the second capacity per unit area greater than the first and third capacities, the invention creates a parameter gradient that directs lithium ion flow away from regions prone to plating. This parameter variation is achieved through controlled application of negative active material layers with different thicknesses or compositions in different regions.
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 configuration enhances the safety of lithium-ion batteries by reducing the risk of lithium plating and dendrite formation, thereby preventing short circuits and improving the overall performance and longevity of the battery.
Implementation Method 1
when an identical quantity of lithium ions are deintercalated from a unit area of the first positive active material layer and from a unit area of the second positive active material layer separately, an active material per unit area of the first negative active material layer is more capable of intercalating lithium ions
Implementation Method 2
The first negative active material layer and the second negative active material layer are located on an identical side of the negative current collector
Data Source
AI summary
An electrochemical including an electrode assembly. The electrode assembly includes a negative electrode plate, a positive electrode plate, and a separator. The negative electrode plate includes a negative current collector. The negative current collector includes a first part and a second part. A first negative active material layer is disposed on one side of the first part. A second negative active material layer and a third negative active material layer are disposed on two sides of the second part respectively. The positive electrode plate includes a positive current collector. The positive current collector includes a third part and a fourth part. A first positive active material layer is disposed on the third part. A second positive active material layer is disposed on the fourth part.