Pouch Battery Cell Edge Sealing Against Moisture Penetration
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Solution Overview
Problem
Pouch-shaped battery cells face issues with humidity penetration and electrolyte leakage due to the permeability of their laminate sheet structure, which can lead to reduced lifespan and stability.
Innovation Solution
A metal piece is mounted in the sealed portions of the battery cell's laminate sheet structure to create a secondary sealed portion, preventing humidity penetration and electrolyte leakage by welding it to the metal layer, thereby enhancing the battery's humidity resistance and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laminate sheet structure is used for the battery case, then the battery cell achieves a pouch-shaped form with low manufacturing cost and lightweight properties, but the laminate sheet exhibits permeability to humidity and electrolyte, leading to penetration and leakage issues
Solution Approach 1:
The battery case uses a multi-layer laminate sheet structure comprising an outer resin layer (oriented nylon), a metal barrier layer (aluminum), and an inner resin layer (cast polypropylene). This composite structure combines the advantages of different materials: the resin layers provide flexibility and sealing, while the metal layer provides barrier properties against humidity and electrolyte penetration, thereby resolving the contradiction between ease of manufacture and reliability.
2Stability of the object's composition
If the inner resin layers are thermally bonded to seal the battery cell, then the battery case achieves a sealed structure, but the thermal bonding process creates potential pathways for humidity penetration and electrolyte leakage
Solution Approach 1:
The sealing structure is segmented into multiple functional layers: the thermal bonding of inner resin layers provides basic sealing, while the metal barrier layer positioned between them provides an additional impermeable barrier. This segmentation ensures that even if thermal bonding creates micro-pathways, the metal layer blocks humidity and electrolyte penetration, resolving the contradiction between sealing integrity and penetration prevention.
3Weight of stationary object
If the battery case is made thinner to reduce size and weight, then the battery cell achieves miniaturization, but the thinner laminate sheet becomes more susceptible to permeability and structural weakness
Solution Approach 1:
The multi-layer laminate structure provides high strength-to-weight ratio. The thin oriented nylon outer layer provides flexibility and low weight, while the aluminum metal layer provides rigid barrier properties and structural reinforcement. This composite construction allows the battery case to be thin and lightweight while maintaining structural strength and resistance to permeability.
4Reliability
If a single-layer metal barrier is used to prevent penetration, then the battery case achieves good barrier properties, but the manufacturing cost increases and the flexibility decreases
Solution Approach 1:
Instead of using a single thick metal layer, the invention uses a thin metal barrier layer sandwiched between two resin layers. This composite structure achieves effective penetration prevention through the metal layer's impermeability, while the thin construction and resin bonding keep manufacturing complexity and cost low, and maintain flexibility for pouch-shaped battery formation.
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 effectively prevents humidity from entering the battery cell and prevents electrolyte leakage, improving the battery's reliability and durability while also reinforcing the outer edges of the laminate sheet, leading to increased strength and stability.
Implementation Method 1
a metal piece for preventing the penetration of humidity into the first space from an outside is mounted in at least one of the second spaces
Implementation Method 2
a battery case includes thermally bondable portions thermally bonded to each other to constitute a first sealed portion of the battery cell
Data Source
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AI summary
Disclosed herein is a battery cell including a battery case, wherein the battery case includes thermally bondable portions thermally bonded to each other to constitute a first sealed portion of the battery cell, a first space for receiving an electrode assembly, and second spaces defined outside the thermally bondable portions, the second spaces constituting the outer edges of the battery case together with the thermally bondable portions, and wherein a metal piece for preventing the penetration of humidity into the first space from the outside is mounted in at least one of the second spaces.