Lead-Insulating Film for Battery Heat-Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium batteries face issues with short-circuiting due to the melting of heat-sealable and lead-insulating films during the heat-sealing process, causing contact between metal leads and the barrier layer, which compromises the integrity of the battery package.
Innovation Solution
A lead-insulating film with a heat-resistant base film and paired resin layers, including a polyolefin resin layer and an acid-modified polyolefin resin layer, is used to prevent contact between the barrier layer and metal leads by maintaining insulation under heat and pressure, ensuring stable sealing of the battery module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer acid-modified polyethylene resin film is used as lead-insulating film, then bonding capability to leads is improved, but heat resistance deteriorates causing film melting during heat-sealing
Solution Approach 1:
The lead-insulating film is divided into three distinct layers: a heat-resistant base film layer (PET, PEN, PPS, or TPX) that maintains structural integrity at high temperatures, and two resin layers (polyolefin resin on the heat-sealable layer side, acid-modified polyolefin resin on the lead side) that provide bonding capabilities. This segmentation allows each layer to specialize in one function, resolving the contradiction between heat resistance and bonding capability.
Solution Approach 2:
The invention uses a composite structure combining heat-resistant base film material with resin materials that have good bonding properties. The base film provides thermal stability while the resin layers provide adhesion to both the heat-sealable layer and the lead, creating a composite material system that achieves both heat resistance and bonding capability simultaneously.
2Reliability
If heat-sealing temperature is increased to ensure proper sealing, then sealing reliability is improved, but risk of film melting and short-circuiting increases
Solution Approach 1:
The heat-resistant base film layer is placed beforehand between the heat-sealable layer and the lead to cushion and prevent short-circuiting. This layer acts as a thermal barrier and physical spacer that maintains insulation even when the heat-sealable layer melts during high-temperature sealing, preventing harmful contact between the lead and barrier layer.
Solution Approach 2:
The lead-insulating film serves as an intermediary element between the heat-sealable layer and the lead. It mediates the heat-sealing process by allowing thermal energy transfer for bonding while preventing direct contact between the melting heat-sealable layer and the conductive lead, thus enabling reliable sealing without short-circuiting.
3Ease of manufacture
If acid-modified polyolefin resin is used for heat-sealable layer, then bonding to metal leads is improved, but manufacturing cost and workability deteriorate
Solution Approach 1:
The acid-modified polyolefin resin is applied locally only where needed - specifically in the resin layer adjacent to the lead - rather than throughout the entire heat-sealable layer. This localized application provides bonding capability at the critical interface while using more economical materials for the rest of the structure, reducing overall manufacturing cost.
Solution Approach 2:
The invention uses a more economical polyolefin resin for the heat-sealable layer instead of expensive acid-modified polyolefin resin throughout. The acid-modified resin is reserved only for the thin layer that actually contacts the lead, effectively using cheaper materials where possible while maintaining necessary performance characteristics.
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 short-circuiting and ensures the battery module is sealed without leakage, maintaining the integrity of the package and preventing corrosion of the barrier layer.
Implementation Method 1
A lead-insulating film with a heat-resistant base film and paired resin layers, including a polyolefin resin layer and an acid-modified polyolefin resin layer, is used to prevent contact between the barrier layer and metal leads by maintaining insulation under heat and pressure
Implementation Method 2
a peripheral part of the package is heat-sealed
Data Source
AI summary
A lithium battery (1) has a battery module (2), a battery package (5) for holding the battery module (2) therein, and leads (4) extending from the battery module (2) and projecting outside from the battery package (5). The battery package (5) is formed from a laminated sheet (10), and a peripheral part (9) of the battery package (5) is heat-sealed. Lead-insulating films (6) are interposed between the peripheral part (9) of the package (5) and the leads (4). Each of the lead-insulating films includes a heat-resistant base film (22), a polyolefin resin layer (21) formed on one of the surfaces of the base film (22) on the side of the laminated sheet (10), and an acid-modified polyolefin resin layer (23) formed on the other surface of the base film (22) on the side of the lead (4).