Dual-Separator Electrode Assembly for Safer Battery Bending
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Solution Overview
Problem
Battery cell safety is compromised due to lithium plating and separator damage during the bending process, leading to short circuits and potential thermal runaway, which affects the service life and reliability of battery cells.
Innovation Solution
An electrode assembly with a dual separator system, where a second separator is laminated with the first separator in the bending region to prevent lithium dendrites and burrs from piercing, ensuring ion permeability and reducing the risk of short circuits, while the second separator's greater thickness and porosity enhance its protective capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single separator is used in the electrode assembly, then the device complexity is low and manufacturing is simple, but the reliability is insufficient due to risk of short circuits from lithium dendrite piercing
Solution Approach 1:
The separator is divided into multiple segments: a first separator and a second separator arranged in sequence between the positive and negative electrode sheets. This segmentation allows each separator layer to provide independent protection against lithium dendrite piercing, significantly improving reliability without requiring a complete redesign of the entire battery structure
Solution Approach 2:
The first and second separators are pre-installed in the electrode assembly before battery operation. This preliminary protective action ensures that lithium dendrites are blocked before they can cause short circuits, addressing the reliability issue proactively rather than reactively
2Reliability
If separator thickness is increased to prevent piercing, then the reliability improves, but the ion permeability may be reduced affecting battery performance
Solution Approach 1:
The total separator thickness requirement is segmented across multiple layers. Each separator layer can be optimized with appropriate thickness and porosity characteristics, allowing the cumulative structure to provide both mechanical strength for piercing resistance and sufficient ion transmission pathways to maintain performance
Solution Approach 2:
The first and second separators can be made from different materials or have different structural characteristics, creating a composite separator system. This allows optimization of each layer for specific functions: one layer for mechanical strength and another for ion permeability, resolving the contradiction between durability and performance
3Reliability
If the bending region is reinforced with additional separators, then the safety in bending regions improves, but the manufacturing complexity increases
Solution Approach 1:
The first and second separators are specifically positioned to provide reinforcement in the bending region where lithium plating and separator damage are most likely to occur. This localized quality enhancement targets the critical vulnerability area without requiring additional separators throughout the entire electrode assembly, minimizing manufacturing complexity while maximizing safety where needed
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 dual separator system effectively reduces the risk of short circuits and improves the safety and service life of the electrode assembly by preventing lithium plating and separator damage, ensuring reliable ion passage and maintaining battery performance.
Implementation Method 1
Both the first separator and the second separator are capable of allowing ions to permeate through
Implementation Method 2
it is difficult for the lithium dendrites or burrs to pierce the first separator and the second separator at the same time
Data Source
AI summary
An electrode assembly includes a first electrode sheet, a second electrode sheet, and a first separator. The first electrode sheet and second electrode sheet are of opposite polarities, the first separator is configured to separate the first electrode sheet and the second electrode sheet. The first electrode sheet, the second electrode sheet, and the first separator are wound in a winding direction. The electrode assembly has a bending region. The bending region is provided with a second separator that is laminated with the first separator and configured to separate the first electrode sheet and the second electrode sheet adjacent to each other. At least part of ions deintercalated from the first electrode sheet are able to pass through the first separator and the second separator and be intercalated in the second electrode sheet.