Method For Manufacturing Positive Electrode Current Collector Coated With Adhesion Enhancement Layer And Positive Electrode Current Collector Coated With Adhesion Enhancement Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face issues with low adhesion strength between the positive electrode active material layer and the current collector, leading to potential detachment, especially with lithium iron phosphate-based materials, and require energy-efficient drying processes for adhesion enhancement layers.
Innovation Solution
A method involving an aqueous slurry with polyvinylidenefluoride-based polymer particles and a conductive material, applied at a specific weight ratio and melting point range, is used to form an adhesion enhancement layer on the current collector, enhancing adhesion strength while maintaining low interfacial resistance and resisting electrolyte dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesion enhancement layer is formed on the current collector to improve adhesion strength, then the adhesion strength between the positive electrode active material layer and the current collector is improved, but the interfacial resistance increases
Solution Approach 1:
The adhesion enhancement layer is formed as a composite material comprising a binder polymer and a conductive material. The binder polymer provides adhesion strength while the conductive material (such as carbon black, acetylene black, or graphite) maintains low interfacial resistance by creating conductive pathways between the current collector and the positive electrode active material layer.
Solution Approach 2:
The adhesion enhancement layer is applied locally only on the current collector surface where adhesion improvement is needed, rather than coating the entire electrode structure. This localized application ensures that the adhesion enhancement function is provided precisely at the current collector interface without unnecessarily increasing interfacial resistance across the entire electrode.
2Strength
If a binder polymer is used to form the adhesion enhancement layer, then the adhesion strength is improved, but the energy required to dry the coated slurry increases
Solution Approach 1:
The binder polymer is selected with specific properties including a glass transition temperature of -50°C to 0°C and a melting point of 50°C to 150°C. These parameter specifications allow the polymer to provide adequate adhesion strength while enabling drying at moderate temperatures, thus reducing the energy required for the drying process compared to using polymers with higher melting points.
3Ease of manufacture
If the positive electrode active material layer is coated directly on the current collector, then the manufacturing process is simple, but the adhesion strength is insufficient leading to detachment
Solution Approach 1:
The adhesion enhancement layer is formed on the current collector before coating the positive electrode active material layer. This preliminary action prepares the current collector surface with enhanced adhesion properties, ensuring that when the active material layer is subsequently coated and dried, it achieves strong adhesion to the current collector without requiring complex manufacturing modifications.
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 improves adhesion strength between the positive electrode active material layer and the current collector, reduces energy consumption in the drying process, and maintains adhesion performance even when exposed to electrolyte solutions, resulting in enhanced lithium secondary battery performance.
Implementation Method 1
drying by thermal treatment at a higher temperature than the melting point of the polyvinylidenefluoride-based polymer particles to form the adhesion enhancement layer
Implementation Method 2
coating the aqueous slurry on at least one surface of a metal current collector and drying by thermal treatment
Data Source
AI summary
A method for manufacturing a positive electrode current collector coated with an adhesion enhancement layer includes preparing an aqueous slurry comprising a first binder polymer comprising polyvinylidene fluoride-based polymer particles having a melting point of 50 to 150° C. and a first conductive material at a weight ratio of 0.5:1 to 8:1; and coating the aqueous slurry on at least one surface of a metal current collector and drying by thermal treatment at higher temperature than the melting point of the polyvinylidene fluoride-based polymer particles to form the adhesion enhancement layer.