Variable-Thickness Separator Structure for Lithium Dendrite Blocking
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Solution Overview
Problem
Existing battery technologies face challenges in improving the safety of battery cells, particularly due to lithium dendrite formation which can lead to short circuits and reduced service life, as traditional methods to enhance separator thickness compromise energy density.
Innovation Solution
An electrode assembly with a separation assembly comprising a reinforcing area and a substrate area, where the reinforcing area is thicker than the substrate area, strategically placed between the positive and negative electrode plates to prevent lithium dendrite passage, while maintaining energy density by minimizing the overall separation assembly amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator thickness is increased to prevent lithium dendrite passage, then safety is improved, but energy density deteriorates due to increased separation assembly amount
Solution Approach 1:
The separation assembly features variable thickness with a reinforcing area (greater thickness) positioned at locations where lithium dendrites are most likely to form and penetrate, while other areas maintain smaller thickness. This local differentiation allows enhanced safety at critical positions without proportionally increasing the overall separation assembly amount, thereby preserving energy density.
2Reliability
If the separator thickness is increased to block lithium dendrites, then the risk of short circuit is reduced, but the service life is prolonged at the cost of reduced energy density
Solution Approach 1:
The separation assembly implements localized thickness enhancement only in the reinforcing area where lithium dendrite penetration risk is highest, rather than uniformly increasing thickness throughout. This selective approach extends service life by blocking dendrites at critical positions while minimizing the overall material volume, thus reducing the negative impact on energy density.
3Quantity of substance
If the separation assembly amount is reduced to increase energy density, then energy density is improved, but safety deteriorates due to increased risk of lithium dendrite passage
Solution Approach 1:
The separation assembly uses a variable thickness design where the reinforcing area provides greater thickness specifically at positions prone to lithium dendrite formation, while other areas use smaller thickness. This localized approach maintains adequate safety at critical positions without requiring a proportional increase in overall separation assembly amount, thereby preserving energy density.
Solution Approach 2:
The separation assembly is divided into functionally distinct regions: a reinforcing area with greater thickness for safety-critical positions, and a substrate area with smaller thickness for non-critical positions. This segmentation allows optimized protection where needed while minimizing overall material usage, balancing safety and energy density.
Data Source
AI summary
Provided in the embodiment of the present application are an electrode assembly, a battery cell, a battery, and an electric apparatus. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separation assembly The separation assembly is configured to separate the positive electrode plate from the negative electrode plate. The separation assembly includes a substrate area and a reinforcing area connected to the substrate area. A thickness of the reinforcing area is greater than a thickness of the substrate area. At least part of the reinforcing area is located between the positive electrode plate and negative electrode plate adjacent to each other. The reinforcing area may be configured to correspond to a position where the negative electrode plate is prone to lithium precipitation.