Polymer-Film Current Collector With Thin Metal Layers for Battery Flexibility
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Solution Overview
Problem
The continuing desire for thinner and lighter energy storage devices poses challenges for the use of traditional metal foils as current collectors, as they are heavy and inflexible, and polymer-based current collectors with plated metal layers have poor thermal reliability and adhesion issues.
Innovation Solution
A current collector is developed comprising a polymer film with an electrically conductive filler and two thin metal layers, each 3 μm or less in thickness, which provides improved adhesion and thermal reliability, and achieves a mid-discharge voltage at least 20% lower than untreated copper foil in lithium-ion battery tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metal foils are used as current collectors, then high electrical conductivity is achieved, but weight and flexibility are compromised
Solution Approach 1:
The current collector uses a composite structure consisting of a polymer film substrate combined with thin metal layers (copper or aluminum) deposited on its surfaces. This composite design achieves high electrical conductivity through the metal layers while the polymer film provides lightweight and flexible properties, resolving the contradiction between conductivity and weight.
Solution Approach 2:
The invention replaces traditional thick metal foils with thin metal layers (1-5 μm) deposited on a polymer film. This thin-film structure maintains electrical conductivity while dramatically reducing weight and improving flexibility, enabling the current collector to bend and conform to different shapes without breaking.
2Weight of moving object
If polymer-based current collectors with plated metal layers are used, then weight and flexibility are improved, but adhesion and thermal reliability deteriorate
Solution Approach 1:
The patent applies surface treatment to the polymer film before depositing metal layers to enhance adhesion. This preliminary action modifies the polymer surface properties (such as creating roughness or chemical groups) to ensure strong bonding between the polymer substrate and metal layers, preventing delamination during battery operation.
Solution Approach 2:
The invention introduces an intermediate layer between the polymer film and metal layers to improve interfacial adhesion. This intermediate layer acts as a mediator that chemically or physically bonds to both the polymer substrate and metal coating, ensuring strong attachment and thermal reliability of the composite structure.
3Ease of operation
If thin metal layers are used on polymer films, then flexibility and weight are improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical lamination or bonding methods with physical vapor deposition (PVD) or chemical vapor deposition (CVD) techniques to deposit metal layers on polymer films. This substitution enables precise control of thin layer thickness and uniform coverage, simplifying the manufacturing process while achieving the desired flexibility and performance.
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 current collector achieves enhanced mechanical flexibility and reduced weight while maintaining high electrical conductivity, thus supporting the development of thinner and lighter energy storage devices with improved performance.
Implementation Method 1
The polymer film includes an electrically conductive filler and has a surface resistivity of 1 Megaohm/square or less
Implementation Method 2
a first metal layer adhered to the polymer film, and a second metal layer adhered to the polymer film
Data Source
AI summary
In a first aspect, a current collector includes a polymer film, a first metal layer adhered to the polymer film, and a second metal layer adhered to the polymer film on a side opposite the first metal layer. The polymer film includes an electrically conductive filler and has a surface resistivity of 1 Megaohm/square or less. The first and second metal layers each have a thickness of 3 μm or less. The current collector has a mid-discharge voltage that is at least 20% lower when compared to an untreated battery-grade copper foil, based on a standard lithium-ion battery half-cell test at a temperature of 25° C. and discharge rate of 2 C or greater.