Dry-Coated Li-Ion Electrode Binder Without NMP Solvents
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Solution Overview
Problem
There is a need for new binders and electrode compositions for Li-ion batteries that are suitable for processing without the use of organic solvents, as existing binders like PVDF require volatile and toxic solvents for dissolution.
Innovation Solution
A non-fibrillizable binder consisting of a fluoropolymer powder with a specific particle size distribution is used for dry-coated electrodes in Li-ion batteries, allowing for solventless processing and improved mechanical integrity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF binder is used with conventional wet-suspension method, then good bonding capability and adhesion are achieved, but volatile organic solvents (NMP) must be used which are toxic and flammable
Solution Approach 1:
The invention changes the physical state of the binder from dissolved (wet method) to powder form (dry method). The PVDF binder is used as a fine powder with specific particle size distribution (D50: 3-8 μm, D90: 15-25 μm) instead of being dissolved in NMP solvent, eliminating the harmful solvent while maintaining bonding capability through optimized particle characteristics
Solution Approach 2:
The invention extracts and removes the harmful NMP solvent from the electrode manufacturing process. By using a solvent-free dry coating method with powdered PVDF binder, the toxic and flammable solvent is completely eliminated while the binder's essential bonding function is preserved through optimized powder properties
2Object-generated harmful factors
If dry (solvent-free) manufacturing process is used, then elimination of volatile organic compounds and higher energy density are achieved, but binder must be adapted to new manufacturing conditions
Solution Approach 1:
The invention adapts the PVDF binder to dry manufacturing by changing its physical form to powder with specific particle size parameters (D50: 3-8 μm, D90: 15-25 μm). This parameter optimization enables the binder to function effectively in solvent-free conditions, achieving both VOC elimination and maintaining binder compatibility
Solution Approach 2:
The invention creates a composite electrode structure where powdered PVDF binder particles are integrated with active material particles. The specific particle size distribution of the binder powder enables effective coating and bonding in dry conditions, achieving compatibility between the binder and the solvent-free manufacturing process
3Strength
If PVDF layer is formed by heating above melting point, then binding strength is maintained, but thermal activation process increases manufacturing cost
Solution Approach 1:
The invention performs preliminary preparation of the PVDF binder by grinding it to specific particle size parameters (D50: 3-8 μm, D90: 15-25 μm) before coating. This pre-processing enables the binder to achieve effective adhesion and binding strength during or after the coating process itself, eliminating the need for separate thermal activation treatment and reducing manufacturing costs
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 this binder ensures cohesive and mechanically intact electrodes with improved adhesion to the metal substrate, reduced binder content, and lower processing temperatures, enhancing the homogeneity and performance of Li-ion battery electrodes.
Implementation Method 1
a thin PVDF layer can form on the NMC particle surface after heating the PVDF to above its melting point
Data Source
AI summary
The present invention relates generally to the field of electrical energy storage in the lithium storage batteries of Li-ion type. More specifically, the invention relates to a non-fibrillizable binder for a dry-coated electrode for Li-ion battery. Another subject matter of the invention is a process for making an electrode using said binder. The invention also concerns the lithium-ion batteries manufactured by incorporating said electrode.