PTFE-Bound Battery Mixture Sheets Without Solvent Viscosity Drift
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Solution Overview
Problem
The production of secondary battery mixtures using lithium-nickel-based composite oxides faces challenges with viscosity changes over time, leading to reduced electrode productivity and performance issues due to the use of solvents that degrade the solid-state electrolyte and limit binder resin compatibility.
Innovation Solution
Employing a fibrillatable PTFE resin as a binder that forms fibrils upon shear stress, eliminating the need for solvents and reducing moisture content, thereby stabilizing the viscosity and enhancing ion conductivity and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a solvent-based binder system is used for lithium-nickel-based composite oxide electrodes, then the mixture can be coated and dried to form electrodes, but the viscosity changes over time leading to reduced productivity and the solvent degrades the solid-state electrolyte
Solution Approach 1:
The invention extracts and eliminates the solvent component from the traditional slurry system. By using a solvent-free binder system with fibrillatable resin and organic liquid, the harmful solvent that causes viscosity changes and electrolyte degradation is removed, while maintaining the coating capability through direct formation of the binder structure.
Solution Approach 2:
The invention changes the physical and chemical parameters of the binder system by using a fibrillatable resin that forms a three-dimensional network structure upon contact with the organic liquid. This parameter change eliminates viscosity instability over time while maintaining manufacturability, resolving the contradiction between ease of manufacture and productivity.
2Ease of manufacture
If conventional binder resins are used with lithium-nickel-based composite oxide, then electrodes can be formed, but the binder resin compatibility is limited and performance issues occur
Solution Approach 1:
The invention uses a composite binder system comprising fibrillatable resin and organic liquid that work synergistically. The fibrillatable resin provides structural integrity through fibril formation, while the organic liquid facilitates the binding process, creating a compatible system specifically optimized for lithium-nickel-based composite oxide electrodes.
Solution Approach 2:
The organic liquid acts as an intermediary between the fibrillatable resin and the lithium-nickel-based composite oxide particles. It facilitates the formation of the binder network and ensures proper adhesion, improving compatibility and reliability of the electrode structure.
3Strength
If polytetrafluoroethylene is fibrillated using high shear treatment with jet mill, then fibrils are formed for binding, but the process complexity increases
Solution Approach 1:
The fibrillatable resin is designed to automatically form fibrils upon contact with the organic liquid during the electrode formation process itself, without requiring separate high shear treatment or jet mill equipment. The resin self-organizes into the desired fibril structure as part of the normal manufacturing process, eliminating the need for complex additional equipment.
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 use of fibrillated PTFE as a binder in secondary battery mixtures improves electrode performance, stability, and ion conductivity, while minimizing solvent usage and electrolyte degradation, resulting in high-strength and high-toughness battery sheets with enhanced handling properties.
Implementation Method 1
a fibrillatable resin is used as the binder and fibrillated to form a secondary battery mixture sheet
Implementation Method 2
a fibrillatable resin that readily forms fibrils when shear stress is applied to fibrillatable resin
Data Source
AI summary
The present disclosure provides a secondary battery mixture that has good properties, a secondary battery mixture sheet containing the mixture, and a secondary battery using the secondary battery sheet. The secondary battery mixture contains a positive electrode active material and a binder, wherein the positive electrode active material is a lithium-nickel-based composite oxide, and the binder is a polytetrafluoroethylene resin.