Bend-Region Barrier Layer in Electrode Assemblies to Limit Lithium Plating
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Solution Overview
Problem
Lithium-ion batteries face issues with lithium precipitation during charging, which can lead to reduced performance, shortened cycle life, and safety risks due to lithium crystals piercing the separator and causing internal short circuits.
Innovation Solution
An electrode assembly with a barrier layer is introduced between the positive and negative electrode plates in the bend region to block deintercalated lithium ions, preventing them from being intercalated into the negative electrode active material layer and reducing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is added to block lithium ions in the bend region, then lithium precipitation is reduced and safety is improved, but device complexity increases
Solution Approach 1:
The electrode assembly is segmented into different functional regions: a bend region with the barrier layer to prevent lithium precipitation, and a non-bend region without the barrier layer to maintain normal lithium ion transport. This segmentation allows the barrier layer to be selectively applied only where needed (at the bend region between adjacent electrode plates), reducing overall complexity while improving safety.
Solution Approach 2:
The barrier layer acts as an intermediary component between the positive and negative electrode plates in the bend region. It selectively blocks lithium ions from transporting between adjacent electrode plates in the bent area, preventing lithium precipitation while allowing normal operation in non-bend regions.
2Reliability
If the barrier layer blocks lithium ions, then lithium precipitation is reduced, but energy density may be affected
Solution Approach 1:
The barrier layer is applied with local quality - it is positioned specifically in the bend region where lithium precipitation occurs, rather than uniformly across the entire electrode assembly. This localized application ensures safety improvement while minimizing impact on overall energy density by allowing full lithium ion transport capacity in non-bend 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
The barrier layer effectively reduces lithium precipitation, enhancing battery safety and extending the service life by maintaining the balance between safety performance and energy density.
Implementation Method 1
the barrier layer blocks at least part of ions deintercalated from a positive electrode active material layer of the positive electrode plate in the bend region during charging, and the ions blocked by the barrier layer cannot be intercalated into a negative electrode active material layer of the negative electrode plate
Data Source
AI summary
An electrode assembly includes a positive electrode plate and a negative electrode plate wound or stacked to form a bend region, and a barrier layer provided at the bend region. At least part of the barrier layer is located between the positive electrode plate and the negative electrode plate that are adjacent to each other, and is configured to prevent at least part of ions deintercalated from the positive electrode plate from being intercalated into the negative electrode plate in the bend region. A ratio of a thickness of the barrier layer to a porosity of the barrier layer is larger than or equal to 3.5 microns and smaller than or equal to 2000 microns.