Lithium Battery Packaging Material Coating Resists Acid
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Solution Overview
Problem
Current lithium cell packing materials face challenges with delamination due to electrolyte solution and hydrofluoric acid exposure, lacking sufficient water resistance and hydrofluoric acid resistance, which is critical for portable and large-scale applications, and existing chemical conversion treatments are environmentally undesirable and costly.
Innovation Solution
A packing material with a multilayer structure comprising a rare earth element-based oxide, phosphoric acid or phosphate, and a cationic polymer with a cross-linking agent, applied as a coating layer on an aluminum foil, enhancing adhesion and resistance without the need for hexavalent chromium, simplifying production and improving environmental sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If multilayer film with thermal adhesive film layer is used for packing material, then the packing material becomes lightweight and allows free shape selection, but the lamination strength deteriorates due to electrolyte solution penetration and hydrofluoric acid generation
Solution Approach 1:
A coating layer is introduced as an intermediary between the aluminum foil layer and the thermal adhesive film layer. This coating layer acts as a protective barrier that prevents electrolyte solution penetration and hydrofluoric acid generation, thereby maintaining lamination strength while preserving the lightweight特性 of the multilayer film structure
Solution Approach 2:
The invention uses a composite structure combining multiple materials: aluminum foil layer, coating layer with specific composition, and thermal adhesive film layer. This composite material approach creates a packing material that is both lightweight and has enhanced resistance to electrolyte solution and hydrofluoric acid, resolving the contradiction between weight and strength
2Reliability
If conventional chemical conversion treatments are used to improve resistance, then electrolyte solution resistance and hydrofluoric acid resistance are enhanced, but environmental sustainability deteriorates due to use of hexavalent chromium
Solution Approach 1:
The invention extracts and removes hexavalent chromium from the chemical conversion treatment process. Instead, it uses an environmentally friendly coating layer with a specific composition that provides the same protective function against electrolyte solution and hydrofluoric acid without the harmful environmental effects
Solution Approach 2:
The invention changes the chemical composition parameters of the coating layer to achieve the desired resistance properties. By adjusting the composition of the coating layer, it provides electrolyte solution and hydrofluoric acid resistance equivalent to conventional treatments but without using hexavalent chromium, thus improving environmental sustainability
3Ease of manufacture
If existing packing material structures are used, then production is maintained at current complexity levels, but water resistance and hydrofluoric acid resistance are insufficient for portable and large-scale applications
Solution Approach 1:
The coating layer is applied in advance to the aluminum foil layer before final assembly. This preliminary action ensures that the protective barrier is already in place, providing water resistance and hydrofluoric acid resistance from the outset without adding significant complexity to the manufacturing process
Solution Approach 2:
The coating layer serves multiple functions simultaneously: it provides water resistance, hydrofluoric acid resistance, and maintains adhesion between layers. This multi-functionality allows the packing material to meet the requirements for both portable and large-scale applications without significantly increasing production complexity
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 provides excellent electrolyte solution resistance, hydrofluoric acid resistance, and water resistance, ensuring the integrity of lithium cells under various conditions while avoiding environmental toxins and reducing production complexity.
Implementation Method 1
a cross-linking agent that causes cross-linking of the cationic polymers
Implementation Method 2
these salts generate hydrofluoric acid via a hydrolysis reaction with moisture
Data Source
Figure 1~2
Figure 3
Figure 4~5
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 onto one surface of a base material layer, wherein the coating layer includes 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.