Layered Battery Electrode Structure for Thick High-Density Coatings
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in achieving high capacity density while maintaining excellent input/output characteristics and cycle durability, particularly due to issues with electrode active material layer thickness and interfacial adhesion between the electrode and current collector.
Innovation Solution
The battery design incorporates a first electrode active material layer with a binder in a crystallized state on a current collector, paired with a second electrode active material layer without a binder in a crystallized state, enhancing adhesion and allowing for increased thickness without cracking, thus improving cycle durability and capacity density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density of the active material in the active material layer is increased, then the energy density of the battery is improved, but the electrolyte is not sufficiently permeated and held, causing deterioration in input-output characteristics and cycle durability
Solution Approach 1:
The invention applies different binder contents to different layers: the first layer (adjacent to current collector) contains binder in crystallized state for strong adhesion, while the second layer (outer layer) contains no binder in crystallized state for high electrolyte permeability. This local differentiation resolves the contradiction between high active material density and sufficient electrolyte penetration.
Solution Approach 2:
The invention uses a composite structure with two distinct electrode active material layers having different compositions and properties. The first layer provides mechanical support and adhesion with binder, while the second layer optimizes electrochemical performance without binder interference, creating a composite system that balances energy density and cycle durability.
2Quantity of substance
If the electrode active material layer is thickened to increase volume energy density, then the capacity density is improved, but cracks are generated in the layer during drying, causing deterioration in battery characteristics
Solution Approach 1:
The binder in crystallized state is localized in the first layer adjacent to the current collector, providing mechanical reinforcement exactly where needed to prevent crack generation during drying and handling. The second layer remains free of crystallized binder, maintaining thickness without compromising structural integrity.
Solution Approach 2:
The first layer with binder in crystallized state is formed beforehand to provide a robust foundation and stress-distributing structure before the second layer is added. This preliminary reinforcement prevents crack propagation throughout the entire thickened electrode active material layer during subsequent drying and processing.
3Quantity of substance
If an electrode active material layer is made without binder to increase capacity density, then the volume energy density is improved, but interfacial adhesion between the layer and current collector becomes insufficient, causing poor cycle durability
Solution Approach 1:
The invention strategically places binder in crystallized state only in the first layer adjacent to the current collector, providing localized adhesion enhancement exactly at the critical interface. The second layer remains binder-free to maximize capacity density, while the first layer's binder ensures sufficient interfacial bonding.
Solution Approach 2:
The electrode active material layer is segmented into two functional layers: the first layer handles adhesion to the current collector with binder, while the second layer handles electrochemical performance without binder. This segmentation allows each layer to optimize its specific function without compromise.
4Quantity of substance
If the binder content in the electrode active material layer is reduced to increase battery capacity per unit volume, then the capacity density is improved, but adhesion between the active material and current collector deteriorates
Solution Approach 1:
The binder in crystallized state is concentrated in the first layer adjacent to the current collector, providing localized adhesion strength exactly where the interface with the current collector requires it. The second layer has reduced or no binder content, maximizing capacity density in the volume that contributes most to electrochemical performance.
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 configuration effectively reduces contact resistance and enhances the battery's energy density and cycle durability, enabling better performance under varying pressure conditions, including those encountered in vehicle applications.
Implementation Method 1
a first electrode active material layer including a first electrode active material and a binder in a crystallized state
Implementation Method 2
This configuration effectively reduces contact resistance and enhances the battery's energy density
Data Source
AI summary
An electrode for a non-aqueous electrolyte secondary battery, includes a current collector; a first electrode active material layer including a first electrode active material, arranged on a surface of the current collector; and a second electrode active material layer including a second electrode active material, arranged on a surface of the first electrode active material layer. The first electrode active material layer includes a binder in a crystallized state, and the second electrode active material layer does not include a binder. A thickness of the second electrode active material layer is 150 μm or more, and a total of a thickness of the first electrode active material layer and the thickness of the second electrode active material layer is 250 μm or more. A ratio of the thickness of the first electrode active material layer to the thickness of the second electrode active material layer is 0.108 or less.