Lithium Diffusion Control Layer for Battery Prelithiation
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Solution Overview
Problem
Lithium secondary batteries face issues with lithium loss and increased resistance due to delayed electrolyte injection after cell assembly, leading to reduced battery capacity and cycle life, and existing solutions do not adequately address these problems.
Innovation Solution
A lithium diffusion rate control layer is formed between the negative electrode mixture layer and the lithium layer using atomic layer deposition, controlling lithium diffusion and minimizing resistance, with a thickness of 0.1 to 100 nm, primarily using materials like Al2O3, TiO2, and ZrO2 to prevent lithium loss and side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium layer is directly laminated on the negative electrode layer for prelithiation, then lithium content in the negative electrode is increased to solve irreversible capacity reduction, but lithium diffuses unevenly into the electrode before electrolyte injection causing increased resistance and lithium loss
Solution Approach 1:
The patent introduces a lithium diffusion control layer as an intermediary between the lithium layer and the negative electrode mixture layer. This intermediate layer controls the diffusion rate of lithium, preventing uneven diffusion and excessive resistance while still allowing sufficient lithium to reach the negative electrode for capacity improvement.
Solution Approach 2:
The patent changes the diffusion parameter by introducing a control layer with specific thickness (0.5-5 μm) and material composition. This parameter change regulates the diffusion rate of lithium, balancing between preventing lithium loss and ensuring adequate lithium supply to the negative electrode.
2Object-affected harmful factors
If an anti-lithiation layer is used to prevent fire during prelithiation, then safety is improved, but the layer thickness of 0.5 to 5μm increases resistance and deteriorates battery performance
Solution Approach 1:
The patent optimizes the thickness parameter of the protective layer to 0.5-5 μm, which is sufficient to prevent direct contact fires but thin enough to minimize resistance impact. The layer composition is also optimized to balance safety and performance.
Solution Approach 2:
The anti-lithiation layer serves as a protective intermediary that prevents direct contact between the lithium layer and flammable materials, eliminating fire hazards while maintaining acceptable electrical performance through optimized thickness and material selection.
3Productivity
If time is delayed before electrolyte injection after cell assembly, then manufacturing flexibility is improved, but lithium of the lithium layer diffuses unevenly into the electrode causing increased resistance and lithium loss
Solution Approach 1:
The lithium diffusion control layer acts as a mediator that prevents premature and uneven lithium diffusion during the delayed period before electrolyte injection. This intermediate layer maintains lithium in the lithium layer until electrolyte injection, after which controlled diffusion occurs, preventing lithium loss while allowing manufacturing flexibility.
Solution Approach 2:
The patent prepares the lithium diffusion control layer in advance during cell assembly, creating a protective barrier before the delayed period. This preliminary action prevents lithium loss during the waiting period, allowing flexible scheduling of electrolyte injection without compromising lithium content.
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 lithium diffusion rate control layer effectively reduces lithium loss and side reactions, improving battery cycle characteristics and maintaining low resistance, thereby enhancing the performance and longevity of lithium ion secondary batteries.
Implementation Method 1
lithium of the lithium layer attached to the negative electrode may be unevenly moved into the electrode (solid-diffusion), thereby increasing resistance
Implementation Method 2
a lithium diffusion rate control layer formed on the negative electrode mixture layer by atomic layer deposition
Data Source
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AI summary
A negative electrode for a lithium secondary battery according to the present invention comprises: a current collector; a negative electrode mixture layer disposed on the current collector; a lithium diffusion rate-controlling layer formed on the negative electrode mixture layer by atomic layer deposition; and a lithium layer disposed on the lithium diffusion rate-controlling layer. The present invention provides a method for prelithiating the negative electrode for a lithium secondary battery and a method for manufacturing a lithium secondary battery comprising the negative electrode. The negative electrode according to the present invention includes a lithium diffusion rate-controlling layer between a lithium thin film and a negative electrode mixture layer, and thereby can control the lithium diffusion rate during a prelithiation process and inhibit lithium loss or side reactions of lithium, thus enhancing cycle characteristics. In addition, according to the manufacturing method of the present invention, a lithium secondary battery is manufactured by forming a lithium diffusion rate-controlling layer having a very small thickness by atomic layer deposition, thereby minimizing a resistance increase in the lithium diffusion rate-controlling layer due to the material characteristics thereof.