Low-Expansion Die Head for Uniform Electrode Slurry Coating
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Solution Overview
Problem
Existing coating devices for secondary battery electrodes struggle to maintain uniform application thickness of electrode mixture slurry, leading to reduced yield and manufacturing tolerance issues, particularly in high-capacity batteries.
Innovation Solution
The electrode mixture slurry coating device employs a die head with a portion adjacent to the fluid path made of a material with a coefficient of linear expansion of 4.0 ppm/K or less, ensuring uniform application thickness by minimizing thermal expansion variations, and optionally using DLC coating and a shim to prevent wear and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional die head material is used, then the die head structure is simple, but the application thickness of the slurry varies significantly
Solution Approach 1:
The patent applies parameter changes by selecting a die head material with a specific coefficient of linear expansion (4.0 ppm/K or less). This material parameter change ensures that the die head dimensions remain stable under thermal conditions, thereby maintaining uniform slurry application thickness without requiring complex structural modifications.
Solution Approach 2:
The patent employs composite materials by using a die head made of a material with a coefficient of linear expansion of 4.0 ppm/K or less. This material selection represents a composite approach that combines low thermal expansion properties with the necessary mechanical strength and chemical resistance, resolving the contradiction between manufacturing precision and device simplicity.
2Manufacturing precision
If the die head material has high fracture toughness, then the die head is more durable, but the application thickness uniformity decreases
Solution Approach 1:
The patent resolves this contradiction by changing the material parameter to one that simultaneously satisfies both requirements. The selected material has a coefficient of linear expansion of 4.0 ppm/K or less while maintaining adequate fracture toughness, achieving both application thickness uniformity and structural durability through optimized material selection.
3Manufacturing precision
If the die head is made lighter, then the handling is easier, but the application thickness control becomes poorer
Solution Approach 1:
The patent addresses this contradiction by changing the material parameter to one with low thermal expansion (4.0 ppm/K or less). This material selection provides sufficient dimensional stability for precise application thickness control while the patent also notes that this approach can result in a relatively light-weight die head, simultaneously satisfying both requirements.
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 stabilizes the application thickness, improving the yield and productivity of secondary battery manufacturing by reducing variations and enhancing the die head's lifespan.
Implementation Method 1
at least a portion, being adjacent to the fluid path, of the die head is formed of a first material having a coefficient of linear expansion of 4.0 ppm/K or less
Data Source
AI summary
An electrode mixture slurry coating device includes: a transport roller that transports a band-shaped base material; and a die head provided at a position opposed to the transport roller, and that discharges and applies an electrode mixture slurry to the base material being transported. The die head includes a fluid reservoir in which the electrode mixture slurry accumulates, a discharge port for discharging the electrode mixture slurry, and a fluid path that provides communication between the fluid reservoir and the discharge port. At least a portion, being adjacent to the fluid path, of the die head is formed of a first material having a coefficient of linear expansion of 4.0 ppm/K or less, and y<2000/√x holds, where x [ppm/K] is the coefficient of linear expansion of the first material, and y [mm] is a length of the discharge port in a longitudinal direction of the die head.