Layered Battery Electrode Structure for Low Resistance Cycling
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Solution Overview
Problem
Existing lithium ion secondary batteries face issues with increased resistance and deteriorated cycle characteristics when using single crystal electrode active materials, and when mixing single and polycrystalline materials, current is concentrated on the polycrystalline material leading to local deterioration.
Innovation Solution
The electrode active material layer is structured with a first layer containing single crystal lithium transition metal composite oxide as the main component and a second layer containing polycrystalline lithium transition metal composite oxide as the main component, optimizing the distribution of Li migration and stability to reduce resistance and improve cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single crystal electrode active material is used, then cycle characteristics are improved, but resistance increases
Solution Approach 1:
The electrode active material layer is divided into two distinct layers: a first layer containing single crystal electrode active material (for improved cycle characteristics) and a second layer containing polycrystalline electrode active material (for reduced resistance). This segmentation allows each layer to contribute its advantageous properties independently, resolving the contradiction between cycle characteristics and resistance.
Solution Approach 2:
Different regions of the electrode active material layer are assigned different material properties: the first layer (closer to the current collector) uses single crystal material with superior cycle characteristics, while the second layer (closer to the electrolyte) uses polycrystalline material with lower resistance. This local differentiation optimizes overall electrode performance by addressing both contradictory requirements in their respective zones.
2Object-affected harmful factors
If single crystal and polycrystalline electrode active materials are mixed, then resistance is reduced, but current concentrates on polycrystalline material causing local deterioration
Solution Approach 1:
Rather than mixing single crystal and polycrystalline materials in a homogeneous layer, the invention segments them into two distinct layers. The first layer contains single crystal material and the second layer contains polycrystalline material, preventing current concentration issues while maintaining the benefits of both material types.
Solution Approach 2:
The invention transitions from a horizontal mixing approach (comparing mixed materials in the same layer) to a vertical stratification approach (stacking different material types in sequential layers). This dimensional change allows both material types to coexist without current concentration problems, as the layered structure directs current flow through both layers sequentially.
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 layered structure achieves both reduced resistance and improved cycle characteristics by leveraging the stability and reactivity of single crystal materials in the first layer and the lower resistance of polycrystalline materials in the second layer.
Implementation Method 1
optimizing the distribution of Li migration and stability to reduce resistance and improve cycle characteristics
Data Source
AI summary
In this disclosure, a battery is provided. The electrode includes an electrode current collector and an electrode active material layer, wherein the electrode active material layer includes a single crystal electrode active material and a polycrystalline electrode active material, and the single crystal electrode active material and the polycrystalline electrode active material are each a lithium transition metal composite oxide, and the electrode active material layer includes a first layer including a first surface opposite to the electrode current collector and a second layer including a second surface on the electrode current collector side, wherein the first layer includes the single crystal electrode active material as a main component of the electrode active material, and the second layer includes the polycrystalline electrode active material as a main component of the electrode active material.