Negative Electrode Active Material Layer Gradient Density
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Solution Overview
Problem
Thickening of the active material layer in conventional non-aqueous electrolyte secondary batteries leads to increased electron and ion transfer resistance, deteriorating high-rate output characteristics, which is undesirable for in-vehicle power sources.
Innovation Solution
A negative electrode with a thickened active material layer coated using a coating agent containing a resin and conductive aid, maintaining porosity between 39.0% and 60.0% and density between 0.60 and 1.20 g/cm3, to enhance ion and electronic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the active material layer is increased to improve energy density, then the energy density is improved, but the output characteristics at high rate deteriorate due to increased electron and ion transfer resistance
Solution Approach 1:
The patent applies local quality by creating a layered structure where the active material layer has different properties at different locations. The inner region (near current collector) has higher density (1.8-2.2 g/cm³) for good electrical contact, while the outer region has lower density (1.4-1.8 g/cm³) for better electrolyte penetration and ion transport. This spatial variation in density allows the thick electrode to maintain both high energy density and good high-rate output characteristics.
Solution Approach 2:
The patent changes the density parameter of the active material layer from a uniform value to a gradient distribution. By controlling the density to decrease from the current collector side toward the outer surface, the patent optimizes both electron conduction (requiring high density) and ion transport (requiring low density/porosity), thereby resolving the contradiction between energy density and high-rate power output.
2Quantity of substance
If the density of the active material is increased to improve energy density, then the energy density is improved, but the electrolyte permeability and holding property deteriorate
Solution Approach 1:
The patent applies local quality by creating a layered structure where the active material layer has different properties at different locations. The inner region (near current collector) has higher density (1.8-2.2 g/cm³) for good electrical contact, while the outer region has lower density (1.4-1.8 g/cm³) for better electrolyte penetration and ion transport. This spatial variation in density allows the thick electrode to maintain both high energy density and good high-rate power output.
Solution Approach 2:
The patent changes the density parameter of the active material layer from a uniform value to a gradient distribution. By controlling the density to decrease from the current collector side toward the outer surface, the patent optimizes both electron conduction (requiring high density) and ion transport (requiring low density/porosity), thereby resolving the contradiction between energy density and high-rate power output.
3Reliability
If the porosity of the active material layer is increased to improve electrolyte permeability, then the electrolyte permeability is improved, but the energy density deteriorates
Solution Approach 1:
The patent applies local quality by creating a layered structure where the active material layer has different properties at different locations. The inner region (near current collector) has higher density (1.8-2.2 g/cm³) for good electrical contact, while the outer region has lower density (1.4-1.8 g/cm³) for better electrolyte penetration and ion transport. This spatial variation in density allows the thick electrode to maintain both high energy density and good high-rate power output.
Solution Approach 2:
The patent changes the density parameter of the active material layer from a uniform value to a gradient distribution. By controlling the density to decrease from the current collector side toward the outer surface, the patent optimizes both electron conduction (requiring high density) and ion transport (requiring low density/porosity), thereby resolving the contradiction between energy density and high-rate power output.
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 improves high-rate output characteristics by maintaining high ion and electronic conductivity, ensuring efficient charge/discharge performance in thickened negative electrode layers.
Implementation Method 1
a coating agent containing a coating resin and a conductive aid
Implementation Method 2
a porosity of the negative electrode active material layer is 39.0% to 60.0%
Data Source
AI summary
A negative electrode for non-aqueous electrolyte secondary battery provides a means for improving output characteristics at a high rate. The negative electrode has a negative electrode active material layer having a thickness of 150 to 1500 μm formed on a surface of a current collector. In addition, the negative electrode active material layer includes coated negative electrode active material particles in which at least a part of a surface of a negative electrode active material is coated with a coating agent containing a coating resin and a conductive aid. Furthermore, a porosity of the negative electrode active material layer is 39.0% to 60.0% and a density of the negative electrode active material layer is 0.60 to 1.20 g/cm3.