Lithium Battery Anode Porosity Gradient for Electrolyte Penetration
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Solution Overview
Problem
Existing lithium secondary battery anodes face challenges with non-uniform porosity, which hinders electrolyte introduction and increases lithium ion diffusion resistance, leading to reduced lifespan and fast charging performance.
Innovation Solution
The anode design features a mixture layer with a lower, middle, and upper portion, each with a porosity of 24% or more, and a porosity difference of 4% or less between the upper and middle portions, ensuring uniform porosity and facilitating electrolyte penetration and lithium ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the anode mixture layer is formed with conventional methods, then the anode can be manufactured, but the porosity is non-uniform across different positions, which hinders electrolyte introduction and increases lithium ion diffusion resistance
Solution Approach 1:
The patent applies local quality by specifying different porosity requirements for different regions of the anode mixture layer. The method controls porosity to be 24% or more in the lower portion (adjacent to current collector), 24% or more in the middle portion, and 24% or more in the upper portion, with specific difference limits between portions. This region-specific porosity control ensures uniform electrolyte distribution and lithium ion diffusion throughout the layer while maintaining manufacturability through controlled processing parameters.
2Ease of operation
If the porosity of the anode mixture layer is increased to facilitate electrolyte introduction, then electrolyte penetration improves, but the structural integrity and mechanical strength may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the porosity parameter within an optimal range (24% or more in each portion with specific differences between portions). This porosity level is sufficient to facilitate electrolyte introduction and lithium ion diffusion while maintaining the structural integrity of the anode mixture layer. The method achieves this balance by controlling processing parameters such as slurry composition, coating conditions, and drying/pressing parameters to attain the target porosity without compromising mechanical strength.
3Speed
If the anode mixture layer has high porosity to improve lithium ion diffusion, then fast charging performance improves, but the density and capacity may be reduced
Solution Approach 1:
The patent applies parameter changes by optimizing the porosity parameter to 24% or more in each portion with controlled differences between portions. This porosity level creates sufficient pathways for rapid lithium ion diffusion to improve fast charging performance while maintaining adequate active material density for high capacity. The method achieves this optimization by controlling the balance between pore formation and active material packing through slurry formulation and processing parameters.
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 design enhances the uniformity of porosity across the anode mixture layer, improving electrolyte introduction and lithium ion diffusion, which results in extended lifespan and superior fast charging performance of the lithium secondary battery.
Implementation Method 1
the porosity of each of the lower portion, the middle portion, and the upper portion is 24% or more, and a difference in porosity between the upper portion and the middle portion is 4% or less
Implementation Method 2
improving electrolyte introduction and lithium ion diffusion
Data Source
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AI summary
Anodes and lithium secondary batteries including the anodes are disclosed. In an embodiment, an anode includes an anode current collector; and an anode mixture layer on at least one surface of the anode current collector. The anode mixture layer includes a lower portion, a middle portion, and an upper portion that are arranged sequentially in a thickness direction from a surface adjacent to the anode current collector to a surface opposite to the anode current collector. Each porosity of the lower portion, the middle portion, and the upper portion is 24% or more, and a difference in porosity between the upper portion and the middle portion is 4% or less.