Negative Electrode Porosity Control for Battery Durability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries for electric vehicles face challenges in maintaining high capacity, high output, and durability due to increased density and porosity issues in the negative electrode active material layer, leading to lithium dendrite formation and electrolyte degradation.
Innovation Solution
The battery design incorporates a negative electrode active material layer with a porosity variation of 6.0% or less, ensuring improved electro-current distribution and reduced side reactions, thereby enhancing durability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density of the negative electrode active material layer is increased to increase capacity, then the capacity increases, but the porosity decreases and permeation of electrolyte solution is inhibited
Solution Approach 1:
The patent applies local quality by creating regions with different porosity characteristics within the negative electrode active material layer. Specifically, it controls porosity to be 30% or more in at least one region while maintaining high overall density, ensuring localized electrolyte permeation pathways that prevent uniform degradation and improve cycle characteristics.
Solution Approach 2:
The patent utilizes porous materials by maintaining high porosity (30% or more) in specific regions of the negative electrode active material layer. This porous structure allows adequate electrolyte solution permeation and lithium ion transport, preventing the inhibition of ion exchange that would otherwise occur in fully dense structures.
2Quantity of substance
If the density of the negative electrode active material layer is increased to increase capacity, then the capacity increases, but reaction becomes non-uniform and lithium dendrites occur
Solution Approach 1:
The patent applies local quality by creating regions with different porosity characteristics within the negative electrode active material layer. Specifically, it controls porosity to be 30% or more in at least one region while maintaining high overall density, ensuring localized electrolyte permeation pathways that prevent uniform degradation and improve cycle characteristics.
Solution Approach 2:
The patent applies parameter changes by controlling the porosity parameter to be 30% or more in specific regions. This parameter control ensures adequate electrolyte penetration and uniform lithium ion distribution, preventing local overcharge/discharge conditions that lead to dendrite formation and non-uniform reactions.
3Quantity of substance
If the area of the battery is increased to increase capacity, then the capacity increases, but the cycle characteristics deteriorate due to porosity variation
Solution Approach 1:
The patent applies local quality by creating regions with different porosity characteristics within the negative electrode active material layer. Specifically, it controls porosity to be 30% or more in at least one region while maintaining high overall density, ensuring localized electrolyte permeation pathways that prevent uniform degradation and improve cycle characteristics.
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 approach results in significantly improved battery durability and capacity retention, particularly in high-capacity, high-density batteries, extending the cruising distance of electric vehicles by maintaining performance even after repetitive charging and discharging.
Implementation Method 1
charge and discharge reactions of a battery occur as ions such as lithium ions are absorbed into and desorbed from an electrode active material
Implementation Method 2
permeation of the electrolyte solution into the negative electrode active material layer is inhibited
Implementation Method 3
the exchange of lithium ions becomes partially difficult
Data Source
Figure 1
Figure 2~3
AI summary
Provided is a non-aqueous electrolyte secondary battery which has improved battery durability in the battery having a high capacity, a high density, and a large area. A non-aqueous electrolyte secondary battery including a power generating element including a positive electrode in which a positive electrode active material layer containing a positive electrode active material is formed on a surface of a positive electrode current collector, a negative electrode in which a negative electrode active material layer containing a negative electrode active material is formed on a surface of a negative electrode current collector, and a separator, a ratio of a rated capacity to a pore volume of the negative electrode active material layer being 1.12 Ah/cc or more, a ratio of a battery area to a rated capacity being 4.0 cm2/Ah or more, and a rated capacity being 30 Ah or more, wherein a variation in porosity in the negative electrode active material layer is 6.0% or less.