Grooved Thick Battery Electrodes for Crack-Resistant Coating Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Secondary batteries face issues with mechanical strength and flexibility due to thick electrode coatings, leading to cracks during production and handling, particularly when bent, and existing methods to improve flexibility, such as forming concavities/convexities, are ineffective in ensuring proper spreadability and may damage the current collector.
Innovation Solution
A method involving the use of a moisture powder with a pendular or funicular state, forming grooves orthogonal to the transport direction on the coating film before drying, using a gas-phase-controlled moisture powder with specific gravity ratios and controlled porosity, to enhance flexibility and minimize cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the electrode active material layer is made thicker to increase capacity, then the mechanical strength of the electrode increases, but the flexibility becomes insufficient and cracks tend to occur
Solution Approach 1:
The coating film is formed with a gas phase remaining inside, creating a porous structure that provides internal void space. This porous architecture allows the thick coating film to compress and deform more easily during bending and winding operations, significantly improving flexibility while maintaining mechanical strength through the overall film structure.
Solution Approach 2:
The invention changes the physical state parameters of the coating film by controlling the retention of gas phase and setting specific moisture content ranges (5-20 wt%). These parameter changes transform the coating film from a dense, rigid structure to a more compliant structure with improved flexibility, allowing thick films to bend without cracking.
2Shape
If a mold is pressed on a dried coating film to form grooves, then the desired concave-convex shape is formed, but the coating film has poor spreadability and the current collector may be damaged
Solution Approach 1:
The grooves are formed on the coating film before the drying step, while the coating film still contains moisture and has not yet become rigid. This preliminary action allows the coating film to be more pliable and easier to deform into the desired grooved shape without requiring excessive force that could damage the current collector.
Solution Approach 2:
The invention utilizes the parameter change of the coating film during the drying process. By forming grooves when the moisture content is higher (before complete drying), the coating film has softer, more adaptable properties that improve spreadability and make groove formation easier without damaging underlying structures.
3Stability of the object's composition
If the coating film is dried completely before forming grooves, then the electrode structure is stable, but the flexibility is insufficient and cracks occur during bending
Solution Approach 1:
The coating film maintains a porous structure with retained gas phase after drying, creating internal voids that act as cushioning spaces. This porous architecture allows the dried and structurally stable coating film to still exhibit flexibility by compressing the porous structure during bending, preventing cracks while maintaining compositional stability.
Solution Approach 2:
The grooves are formed before the drying step, when the coating film is still pliable. This preliminary groove formation ensures that the shape is established while the material is more compliant, and then the drying process stabilizes this pre-formed structure, resulting in a stable yet flexible final product.
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
The method effectively improves the flexibility of the electrode coating, reducing cracks during production and enhancing the quality of the electrode, thereby minimizing capacity loss and short-circuit risks in secondary batteries.
Implementation Method 1
a moisture powder formed of agglomerated particles containing at least an electrode active material, a binder resin, and a solvent is prepared, with a solid phase, a liquid phase, and a gas phase in at least 50 number % or more of the agglomerated particles forming a pendular state or a funicular state
Implementation Method 2
a moisture powder formed of agglomerated particles containing at least an electrode active material, a binder resin, and a solvent is prepared, with a solid phase, a liquid phase, and a gas phase in at least 50 number % or more of the agglomerated particles forming a pendular state or a funicular state
Implementation Method 3
a coating film composed of the moisture powder is formed on the electrode current collector by using the moisture powder, with a gas phase of the coating film being remained
Data Source
AI summary
A method of producing an electrode disclosed here includes a step in which a moisture powder formed of agglomerated particles; a step in which a coating film composed of the moisture powder is formed on an electrode current collector by using the moisture powder, with a gas phase of the coating film being remained, so that the average film thickness of the coating film is 50 μm or more; a step in which the coating film on the electrode current collector is transported, concavo-convex transfer is performed by using a roll mold, and thus a plurality of grooves extending in a direction orthogonal to a transport direction are formed on a surface part of the coating film so that a depth of the groove satisfies ( 9/10×t1)>t2, and a step in which the coating film formed on the electrode current collector is dried to form an electrode active material layer.