Composite Current Collector Coating for Battery Delamination Resistance
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Solution Overview
Problem
Current collectors in secondary batteries face issues such as delamination and reduced energy density due to low adhesion between metal and polymer layers, leading to poor cycle and storage performance, especially at high temperatures and after long cycles.
Innovation Solution
A composite current collector with an organic support layer, an intermediate coating composed of a resin composition with specific adhesion properties, and a conductive layer, where the adhesion of the second resin to both the support and conductive layers is higher than the first resin, enhancing interface bonding and electrolyte resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal current collector is used with large thickness to avoid fracture, then mechanical strength is improved, but gravimetric energy density deteriorates
Solution Approach 1:
The patent uses a composite current collector structure consisting of a metal foil layer and a polymer layer. The metal foil provides mechanical strength and electrical conductivity, while the polymer layer reduces overall density and prevents through-thickness cracking. This composite approach allows the current collector to maintain adequate mechanical strength with reduced thickness, thereby improving gravimetric energy density.
2Weight of moving object
If a composite current collector with metal polymer film is used to reduce density, then gravimetric energy density is improved, but adhesion between metal and polymer layers deteriorates
Solution Approach 1:
The patent modifies the surface properties of the metal foil layer through surface treatment processes such as roughening or chemical treatment. This changes the surface parameters to enhance mechanical interlocking and chemical bonding with the polymer layer, thereby improving adhesion while maintaining the low-density composite structure.
Solution Approach 2:
The patent introduces an intermediate coating layer between the metal foil and polymer layers. This intermediate layer serves as a mediator that improves interfacial adhesion by providing compatible surface properties for both metal and polymer, preventing delamination during battery cycling and storage.
3Weight of moving object
If the thickness of metal current collector is reduced to improve energy density, then gravimetric energy density is improved, but mechanical strength and resistance to fracture deteriorate
Solution Approach 1:
The patent employs a composite structure where a thin metal foil layer is combined with a polymer layer. The metal foil provides electrical conductivity and partial mechanical strength, while the polymer layer prevents through-thickness cracking and reduces density. This allows the current collector to be thinner without sacrificing fracture resistance, thereby improving gravimetric energy density.
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 reduces delamination, maintains good electrical conductivity, and significantly improves the gravimetric energy density and cycle performance of secondary batteries by balancing adhesion and electrolyte resistance.
Implementation Method 1
the adhesion of the first resin to the organic support layer is less than the adhesion of the second resin to the organic support layer; the adhesion of the first resin to the conductive layer is less than the adhesion of the second resin to the conductive layer
Data Source
AI summary
A current collector includes: an organic support layer; a conductive layer; an intermediate coating disposed between the organic support layer and the conductive layer, wherein the intermediate coating includes a resin composition at least including a first resin and a second resin; the adhesion of the first resin to the organic support layer is less than the adhesion of the second resin to the organic support layer; the adhesion of the first resin to the conductive layer is less than the adhesion of the second resin to the conductive layer.