PVDF Polymer Composition for Low-NMP Electrode Coating
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Solution Overview
Problem
Vinylidene fluoride polymers with low swelling and solubility in N-methyl-2-pyrrolidone (NMP) result in reduced smoothness of electrode surfaces due to sedimentation and swelling, making it difficult to reduce NMP usage and improve productivity.
Innovation Solution
A vinylidene fluoride polymer composition with a melting point of 130°C or higher, specific viscosity ratios, and the presence of a surfactant to prevent sedimentation, allowing for reduced NMP use and smooth electrode formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of NMP is reduced to decrease solvent removal time, then productivity is improved, but the electrode mixture becomes difficult to coat due to increased viscosity
Solution Approach 1:
The patent changes the physical and chemical parameters of the vinylidene fluoride polymer by controlling its melting point (130°C or higher) and crystallinity. This parameter modification allows the polymer to maintain low swelling and solubility in NMP, thereby keeping the electrode mixture viscosity low even with reduced NMP content, which preserves coatability while improving productivity
Solution Approach 2:
The patent creates a composite system by combining vinylidene fluoride polymer with specific additives including dispersants and plasticizers. This composite approach modifies the overall properties of the electrode mixture, enabling reduced NMP content while maintaining proper flow characteristics and coatability
2Productivity
If vinylidene fluoride polymer with reduced solubility in NMP is used to reduce NMP amount, then productivity is improved, but electrode surface smoothness is reduced
Solution Approach 1:
The patent precisely controls the melting point parameter of the vinylidene fluoride polymer (130°C or higher) and its crystallinity to achieve optimal balance. This parameter optimization reduces NMP swelling and solubility while preventing excessive sedimentation, thereby maintaining electrode surface smoothness even with reduced NMP content
Solution Approach 2:
The patent introduces dispersants and plasticizers as intermediary substances that mediate between the vinylidene fluoride polymer and NMP. These additives prevent particle aggregation and sedimentation, maintaining uniform dispersion and smooth electrode surfaces while allowing reduced NMP usage
3Ease of operation
If typical PVDF is used as binding agent, then coatability is ensured, but solvent removal time increases production cost
Solution Approach 1:
The patent modifies the key parameter of the vinylidene fluoride polymer - its melting point - to be 130°C or higher. This parameter change fundamentally alters the polymer's interaction with NMP, reducing swelling and solubility, which enables reduced NMP content while maintaining coatability and reducing solvent removal time
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 composition maintains low viscosity and prevents swelling, enabling reduced NMP usage, improved productivity, and smooth electrode surfaces.
Implementation Method 1
the vinylidene fluoride polymer dispersion is dried for 2 hours in a thermostatic vessel at 130°C with nitrogen circulation
Implementation Method 2
the presence of a surfactant to prevent sedimentation
Implementation Method 3
the crystallinity of the vinylidene fluoride polymer is increased to reduce the swelling and solubility in NMP
Data Source
AI summary
An objective is to provide a vinylidene fluoride polymer composition that is difficult to swell and dissolve in N-methyl-2-pyrrolidone and can form an electrode with a smooth surface. The vinylidene fluoride polymer composition contains a vinylidene fluoride polymer with a melting point of 130°C or higher. When the vinylidene fluoride polymer composition and N-methyl-2-pyrrolidone are mixed to prepare a vinylidene fluoride polymer dispersion with a content of the vinylidene fluoride polymer of 6 mass%, a ratio of a viscosity of the vinylidene fluoride polymer dispersion at 30°C to a viscosity of N-methyl-2-pyrrolidone at 30°C is 20 or less, and when the vinylidene fluoride polymer dispersion is stirred and then allowed to stand for 15 minutes, a rate of change in content of the vinylidene fluoride polymer in an upper 40 volume% area of the vinylidene fluoride polymer dispersion before and after the standing is 2 mass% or less.