Secondary Battery Aluminum Pouch Film for HF and Moisture Barrier
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Solution Overview
Problem
Aluminum pouch films for secondary batteries face challenges in maintaining long-term reliability and safety under high temperature and high humidity environments due to issues with oxygen and moisture transmission, as well as the generation and transmission of corrosive HF gas, which can lead to corrosion and damage.
Innovation Solution
An aluminum pouch film structure that includes an aluminum film layer, an outer resin layer, and an inner resin layer comprising polyolefin, ethylene vinyl alcohol copolymer (EVOH), and an ionic polymer (ionomer) resin, which enhances oxygen and moisture barrier properties and adhesion, while preventing HF gas transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an aluminum film layer is used in the pouch structure, then adhesion between pouches and protection of the battery cell is improved, but the aluminum film layer is susceptible to corrosion by HF gas generated from electrolyte solution reactions, leading to pouch damage and reduced reliability
Solution Approach 1:
An inner resin layer is introduced as an intermediary between the aluminum film layer and the electrolyte solution. This layer acts as a barrier that prevents direct contact between HF gas (generated from electrolyte solution reactions) and the aluminum film, thereby eliminating the corrosion pathway while preserving the adhesion function of the aluminum layer.
Solution Approach 2:
The pouch structure is designed as a composite material system consisting of multiple layers with distinct functions: the aluminum film layer provides adhesion and mechanical strength, while the inner resin layer provides chemical resistance and HF gas barrier properties. This composite structure allows each material to perform its optimal function without suffering from its individual limitations.
2Ease of manufacture
If the inner resin layer uses only polyolefin resin, then ease of manufacture and adhesion are maintained, but oxygen and moisture transmission occurs, allowing HF gas generation and compromising safety
Solution Approach 1:
The inner resin layer is designed as a composite material combining polyolefin resin (for ease of manufacture and adhesion) with EVOH (for oxygen and moisture barrier properties). This composite structure achieves both processing ease and harmful factor prevention without compromising either aspect.
Solution Approach 2:
Different regions of the inner resin layer have different functional qualities: the polyolefin component provides manufacturing ease and adhesion properties, while the EVOH component locally provides oxygen and moisture barrier functionality. Each material is placed where its specific properties are most needed.
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 proposed film structure significantly improves durability and safety by suppressing HF gas generation and transmission, maintaining long-term reliability under harsh conditions.
Implementation Method 1
inner resin layer that is excellent in performance of preventing oxygen and moisture transmission
Implementation Method 2
inner resin layer that is excellent in performance of preventing oxygen and moisture transmission
Implementation Method 3
performance of preventing HF gas transmission
Implementation Method 4
an inner resin layer is formed by a polyolefin such as polyethylene (PE), casted polypropylene (cPP) or polypropylene (PP) or a copolymer thereof in order for adhesion between a lower surface of the upper pouch and an upper surface of the lower pouch
Implementation Method 5
a functional polymer film layer such as a polyethylene terephthalate (PET) resin, a polyethylene naphthalate (PEN) resin, a nylon resin or a liquid crystal polymer (LCP) resin is laminated as an outer resin layer in order to protect the battery cell from external impact
Implementation Method 6
The aluminum film layer exposed to an electrolyte solution as above may be corroded by causing a chemical reaction with the electrolyte liquid, oxygen or moisture
Data Source
AI summary
An aluminum pouch film for a secondary battery is disclosed. The aluminum pouch film contains an aluminum film layer; an outer resin layer laminated on one surface of the aluminum film layer; and an inner resin layer laminated on the other surface of the aluminum film layer. The inner resin layer contains a polyolefin resin, an ethylene vinyl alcohol copolymer (EVOH) and an ionomer resin.