Battery Electrode Assembly Barrier Layer for Bend-Region 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, blocking deintercalated ions and preventing them from being intercalated into the negative electrode active material layer, thereby reducing lithium precipitation and enhancing safety and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a barrier layer is added between positive and negative electrode plates in the bend region, then lithium precipitation is reduced and safety is improved, but device complexity increases
Solution Approach 1:
The electrode assembly is divided into different regions: a bend region with the barrier layer and a non-bend region without the barrier layer. This segmentation allows the barrier layer to be selectively applied only where needed (in the bend region where lithium precipitation occurs), rather than throughout the entire electrode assembly, thus improving safety while minimizing added complexity
Solution Approach 2:
The barrier layer is applied locally only in the bend region between adjacent positive and negative electrode plates, rather than uniformly across the entire electrode assembly. This local application targets the specific area where lithium precipitation occurs during charging, improving safety without unnecessarily increasing overall device complexity
2Reliability
If a barrier layer is added to block ions, then lithium precipitation is reduced, but energy density decreases
Solution Approach 1:
The barrier layer is segmented to occupy only the bend region between adjacent electrode plates, allowing ion transport in the non-bend region to remain unaffected. This ensures that energy density is maintained in areas where the barrier layer is not present, while still achieving lithium precipitation prevention in the critical bend region
Solution Approach 2:
The barrier layer's ion-blocking property is applied locally only in the bend region, while the rest of the electrode assembly maintains full ion permeability. This localized approach prevents lithium precipitation where it occurs most frequently without significantly impacting the overall energy density of the battery
3Duration of action of stationary object
If the barrier layer blocks deintercalated ions, then lithium precipitation is reduced and service life is extended, but charging efficiency may be affected
Solution Approach 1:
The barrier layer is segmented to block ions only in the bend region, while leaving the non-bend regions open for efficient ion transport. This segmentation ensures that the majority of ion transport pathways remain unobstructed, maintaining charging efficiency while preventing lithium precipitation in the vulnerable bend region over extended service life
Solution Approach 2:
The ion-blocking function is localized to the bend region where lithium precipitation occurs, while the rest of the electrode assembly maintains high ion conductivity. This localized quality control extends service life by preventing degradation in the bend region without significantly impeding overall charging efficiency
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, improving the safety and service life of lithium-ion batteries by maintaining the balance between safety performance and energy density.
Implementation Method 1
The barrier layer is provided between the positive electrode plate and the negative electrode plate that are adjacent to each other, so that 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
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.