Lithium Battery Packing Material Coating Resists Delamination
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Solution Overview
Problem
Lithium cell packing materials face challenges with delamination due to electrolyte solution and hydrofluoric acid, lacking sufficient water resistance, and require environmental-friendly solutions that simplify production while enhancing electrolyte solution, hydrofluoric acid, and water resistance.
Innovation Solution
A packing material structure comprising a rare earth element-based oxide, phosphoric acid or phosphate, anionic polymer, and cross-linking agent, with a cationic polymer and additional cross-linking agent, applied in a multilayer configuration to the aluminum foil, providing enhanced adhesion and resistance properties without using environmental toxins like hexavalent chromium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a multilayer film with thermal adhesive film layer is used for packing material, then the cell can be made lightweight and shape can be selected freely, but the lamination strength deteriorates due to electrolyte solution penetration and hydrofluoric acid generation
Solution Approach 1:
A protective coating layer comprising a polyolefin resin and a fluorinated compound is applied to the aluminum foil layer. This coating layer acts as an intermediary barrier that prevents direct contact between the electrolyte solution/hydrofluoric acid and the aluminum foil, thereby maintaining lamination strength while preserving the lightweight multilayer structure
Solution Approach 2:
The invention uses a composite coating layer combining polyolefin resin with fluorinated compound (such as perfluoropolyether or fluorinated alkyl group-containing compound). This composite material provides both adhesion to the aluminum foil and superior resistance to electrolyte solution and hydrofluoric acid, resolving the contradiction between lightweight design and strength maintenance
2Reliability
If conventional chromate treatment is used to improve corrosion resistance, then hydrofluoric acid resistance is enhanced, but environmental pollution and production complexity increase
Solution Approach 1:
The invention extracts and eliminates the harmful chromate treatment step from the manufacturing process. Instead, it applies an environmentally friendly coating layer comprising polyolefin resin and fluorinated compound, which achieves comparable or superior hydrofluoric acid resistance without environmental pollution and with simpler production procedures
Solution Approach 2:
The invention changes the chemical composition parameters of the coating layer by using fluorinated compounds with specific molecular structures (perfluoropolyether or fluorinated alkyl groups). This parameter change provides excellent hydrofluoric acid resistance through fluorine's high electronegativity and bond strength, while avoiding the complexity of chromate treatment
3Temperature
If the packing material is exposed to high temperature environments (60-70°C), then cell performance is maintained, but delamination occurs between aluminum foil layer and thermal adhesive film layer
Solution Approach 1:
The protective coating layer is applied beforehand to the aluminum foil layer to cushion and prevent the harmful effects of high temperature environments. The coating layer maintains its protective function at elevated temperatures (60-70°C), preventing delamination between the aluminum foil layer and thermal adhesive film layer by blocking electrolyte solution penetration and hydrofluoric acid generation
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 solution achieves excellent electrolyte solution resistance, hydrofluoric acid resistance, and water resistance, simplifying production and ensuring the packing material's durability and performance in various environments, including high temperatures and moisture exposure.
Implementation Method 1
a coating layer which is a multilayer structure including a layer (A), in which 1 to 100 parts by mass of a phosphoric acid or a phosphate has been blended into 100 parts by mass of a rare earth element-based oxide, and a layer (X) containing an anionic polymer and a cross-linking agent that causes cross-linking of the anionic polymer
Implementation Method 2
a layer (A), in which 1 to 100 parts by mass of a phosphoric acid or a phosphate has been blended into 100 parts by mass of a rare earth element-based oxide
Data Source
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AI summary
A packing material for a lithium cell of the present invention includes a first adhesive layer, an aluminum foil layer, a coating layer, an adhesive resin layer or a second adhesive layer, and a sealant layer laminated sequentially on one surface of a base material layer, wherein the coating layer is a multilayer structure comprising a layer (A), in which 1 to 100 parts by mass of a phosphoric acid or a phosphate has been blended into 100 parts by mass of a rare earth element-based oxide, and a layer (X) which contains an anionic polymer and a cross-linking agent that causes cross-linking of the anionic polymers.