Lithium-Ion Cell Packaging Adhesion via Undercoat Treatment
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Solution Overview
Problem
Current packaging materials for lithium ion cells face challenges in maintaining long-term reliability due to corrosion and adhesion issues between the aluminum foil and base material layers, particularly in humid environments, and existing chemical conversion treatments are costly and environmentally hazardous.
Innovation Solution
A laminate structure comprising an adhesive layer, an undercoat treated layer with crosslinking resins, a rare earth element oxide, and phosphoric acid or phosphate, which enhances adhesion without the need for chemical conversion treatments, ensuring high thermal and electrolytic solution resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical conversion treatment is used to improve adhesion between aluminum foil and base material, then adhesion is enhanced, but manufacturing cost increases and environmental harm occurs
Solution Approach 1:
The invention extracts and eliminates the chemical conversion treatment step from the manufacturing process. Instead of using chromate or other chemical conversion treatments, the patent applies a primer coating directly to the aluminum foil surface, followed by lamination with the base material layer, thereby removing the harmful chemical treatment while maintaining adhesion.
Solution Approach 2:
The invention introduces a primer coating as an intermediary layer between the aluminum foil and the base material. This primer layer serves as a mediator that provides adequate adhesion without requiring chemical conversion treatment of the aluminum foil, thus resolving the contradiction between adhesion strength and manufacturing simplicity.
2Reliability
If moisture removal storage is performed to prevent corrosion, then reliability is improved, but lifting between layers occurs due to residual stress
Solution Approach 1:
The invention performs preliminary moisture removal from the base material layer before lamination, and incorporates moisture-absorbing agents in the primer coating and interlayer. This preliminary action prevents moisture-related corrosion while avoiding the need for prolonged high-temperature storage that would cause lifting.
Solution Approach 2:
The invention changes the moisture control approach from high-temperature prolonged storage to low-temperature rapid drying combined with moisture-absorbing agents in the coating layers. This parameter change achieves corrosion protection without inducing thermal stress that causes lifting.
3Strength
If electrolytic solution permeates into sealant layer, then adhesion is maintained initially, but laminate strength decreases over time due to corrosion
Solution Approach 1:
The invention introduces an adhesion promoter layer as an intermediary between the sealant layer and the aluminum foil. This adhesion promoter acts as a barrier that prevents electrolytic solution from penetrating into the sealant layer while maintaining strong adhesion, thus preserving long-term laminate strength.
Solution Approach 2:
The invention uses composite material structure with multiple functional layers including primer coating, adhesion promoter, and sealant layer. Each layer is designed with specific properties to resist electrolytic solution penetration while maintaining adhesion, achieving both initial strength and long-term durability.
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 improved adhesion and long-term reliability between the base material and aluminum foil layers, preventing corrosion and leakage, while being environmentally friendly and cost-effective.
Implementation Method 1
a crosslinking resin formed of (A1) a resin having two or more nitrogen-containing functional groups and (A2) a resin having a reactive functional group capable of reaction with the nitrogen-containing functional groups
Implementation Method 2
an undercoat treated layer, an aluminum foil layer, a corrosion inhibition treatment layer
Data Source
Figure 1~2
Figure 3~4
AI summary
A packaging material for lithium ion cell is comprised of a laminate obtained by successively laminating, on one surface of a base material, an adhesive layer, an undercoat treated layer, an aluminum foil layer, a corrosion inhibition treatment layer, an adhesive resin layer and a sealant layer. The undercoat treated layer contains the following components (A), (B), and (C). A total amount of the components (B) and (C) is at 200 to 12000 parts by mass per 100 parts by mass of the component (A). (A) A crosslinking resin formed of a resin (A1) having two or more nitrogen-containing functional groups and a resin (A2) having a reactive functional group capable of reaction with the nitrogen-containing functional groups. (B) A rare earth element oxide. (C) Phosphoric acid or a phosphate salt.