Layered Composite Electrode for Uniform Lithium Supplementation
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Solution Overview
Problem
Current lithium supplementation methods for lithium-ion batteries result in non-uniform distribution of lithium elements, leading to over-supplementation in some areas and insufficient supplementation in others, which affects battery performance and lifetime, and can cause side reactions due to direct mixing of lithium supplement agents with active materials.
Innovation Solution
A composite electrode structure is designed with n-layer active substance layers and n-1-layer lithium supplement layers alternately stacked, where the porosity of lithium supplement layers increases gradually away from the current collector, enhancing lithium ion diffusion and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium supplement agent is mixed with active material of electrode, then lithium supplementation is achieved, but side reactions occur and uniformity is poor
Solution Approach 1:
The electrode is divided into multiple thin layers (n-layer active substance layers and n-1-layer lithium supplement layers) stacked alternately. This segmentation allows lithium supplement layers to be distributed throughout the electrode thickness, providing uniform lithium supplementation while preventing direct contact between lithium supplement agent and active material, thus avoiding side reactions.
Solution Approach 2:
The lithium supplement layers act as intermediary structures between the current collector and the active substance layers. These intermediary layers provide a controlled interface for lithium ion diffusion without allowing direct mixing between lithium supplement agent and active material, preventing harmful side reactions while ensuring adequate lithium supplementation.
2Quantity of substance
If conventional lithium supplementation method is used, then lithium ions are added to compensate capacity loss, but infiltration rate is slow and uniformity is poor
Solution Approach 1:
By dividing the electrode into multiple thin alternating layers, the diffusion distance for lithium ions is significantly reduced. Each lithium supplement layer is positioned close to active substance layers, creating multiple short diffusion paths throughout the electrode, thereby dramatically increasing the infiltration rate and uniformity of lithium ion distribution.
Solution Approach 2:
The invention transitions from conventional two-dimensional mixing of lithium supplement agent with active material to a three-dimensional layered structure. This dimensional change creates multiple interfaces and shortens the diffusion path from the surface to the interior of the electrode, enabling faster and more uniform lithium ion infiltration throughout the entire electrode volume.
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
This structure improves lithium supplementation rate and efficiency, ensures uniform distribution, and reduces initial capacity loss, thereby increasing energy density and cycle performance.
Implementation Method 1
the diffusion path of the lithium ions is shorter, and the diffusion rate of the lithium ions can be accelerated
Implementation Method 2
porosity of the n-1-layer lithium supplement layers gradually increases along a direction away from the current collector
Data Source
AI summary
A composite electrode, a manufacturing method thereof, and a lithium-ion battery are provided. The composite electrode includes a current collector; and a composite material layer disposed on at least one side surface of the current collector. The composite material layer comprises n-layer active substance layers and n-1-layer lithium supplement layers that are stacked at intervals, in which n is greater than or equal to 3 and n is an integer. A side of the composite material layer which is adjacent to the current collector is one of the n-layer active substance layers. Porosity of the n-1-layer lithium supplement layers gradually increases along a direction away from the current collector.