HNBR Cathode Binder Composition for Room-Temperature GVL Processing
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Solution Overview
Problem
Existing cathode binders like PVDF are unsafe, heavy, and require toxic solvents like NMP, while alternatives in γ-valerolactone face solubility issues and high processing temperatures.
Innovation Solution
A polymer composed of monomer units from 1,3-butadiene and acrylonitrile, optionally with methacrylic acid, which is soluble in γ-valerolactone at room temperature, providing safe and efficient cathode binder solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF is used as cathode binder, then good electrochemical stability is achieved, but safety deteriorates due to fluorine corrosion and hydrogen fluoride formation
Solution Approach 1:
The patent removes fluorine-containing monomer units from the polymer composition entirely, replacing PVDF with a fluorine-free polymer made from 1,3-butadiene and acrylonitrile. This extraction of the harmful fluorine element eliminates corrosion issues and hydrogen fluoride formation while maintaining binder functionality through alternative polymer chemistry.
Solution Approach 2:
The patent employs a composite polymer system combining 1,3-butadiene and acrylonitrile monomer units in specific ratios (65-95 wt% butadiene, 5-35 wt% acrylonitrile). This composite approach creates a binder material that achieves both mechanical adhesion properties and electrochemical stability without relying on fluorinated polymers, resolving the safety-reliability contradiction.
2Reliability
If PVDF is used as cathode binder, then good binding performance is achieved, but weight increases due to high density
Solution Approach 1:
The patent fundamentally changes the density parameter of the binder material by substituting PVDF (high density) with a hydrocarbon-based polymer composed of 1,3-butadiene and acrylonitrile (lower density). This parameter change in material composition reduces the overall battery weight while preserving essential binding functions through optimized polymer structure and monomer ratios.
3Object-affected harmful factors
If γ-valerolactone is used as solvent, then non-toxic and green processing is achieved, but PVDF solubility deteriorates requiring high temperatures
Solution Approach 1:
The patent changes the chemical structure parameter of the binder polymer to be compatible with γ-valerolactone solvent. By using 1,3-butadiene and acrylonitrile-based polymers instead of PVDF, the material achieves appropriate solubility parameters that allow effective dissolution in γ-valerolactone at manageable temperatures, enabling non-toxic processing without extreme thermal conditions.
4Object-affected harmful factors
If γ-valerolactone is used as solvent, then non-toxic processing is achieved, but gel formation deteriorates when cooling solutions
Solution Approach 1:
The patent adjusts the polymer composition parameters (specific monomer ratios of 1,3-butadiene and acrylonitrile) to control the solution's thermal and rheological properties. This composition optimization prevents gel formation during cooling by ensuring appropriate glass transition temperature and chain flexibility, maintaining solution stability throughout the processing temperature range while using non-toxic γ-valerolactone solvent.
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 polymer offers high electrochemical stability, safety, and reduced density, enabling efficient cathode preparation with non-toxic solvents and maintaining capacity retention in battery cells.
Implementation Method 1
the polymer is soluble in γ-valerolactone at room temperature
Data Source
AI summary
The invention relates to a polymer comprising or essentially consisting of monomer units derived from 1,3-butadiene, acrylonitrile and optionally, methacrylic acid, wherein the weight content of monomer units derived from 1,3-butadiene is at most 65 wt.-%, relative to the total weight of the polymer. The polymer is useful for manufacturing a cathode for a battery cell. The invention further relates to a cathode of a battery cell comprising the polymer as well as to a composition comprising the polymer and γ-valerolactone.