PVDF Binder Slurry Solvent System Without NMP Toxicity
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Solution Overview
Problem
Current binder compositions for electrical storage devices, such as batteries, rely on N-methyl-2-pyrrolidone (NMP) as a solvent, which is toxic and poses health and environmental concerns, necessitating the development of alternative solvent systems that maintain adhesion, interconnectivity, and durability while being environmentally friendly.
Innovation Solution
A binder composition comprising a fluoropolymer with a solvent system consisting of a trialkyl phosphate and a co-solvent with lactone or sulfoxide/sulfone functional groups, where the trialkyl phosphate and co-solvent comprise at least 50% of the solvent system, enhancing adhesion and interconnectivity without using NMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMP is used as a solvent for PVDF binder, then adhesion and interconnectivity of electrode materials are improved, but health and environmental safety deteriorate due to toxicity
Solution Approach 1:
The patent changes the chemical composition parameters of the solvent system by replacing NMP with a mixture of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC). This parameter change maintains the necessary adhesion and interconnectivity properties while eliminating the toxicity associated with NMP, thus resolving the contradiction between reliability and harmful factors.
Solution Approach 2:
The patent employs a composite solvent system combining DMC and EMC in specific proportions (70:30 to 30:70 weight ratio). This composite approach leverages the complementary properties of both solvents to achieve the desired adhesion and interconnectivity without the toxic effects of NMP, effectively resolving the technical contradiction.
2Object-affected harmful factors
If alternative solvents are used to replace NMP, then health and environmental safety are improved, but adhesion and interconnectivity properties deteriorate
Solution Approach 1:
The patent optimizes the concentration parameters of DMC and EMC in the solvent system to achieve the desired adhesion and interconnectivity. By carefully adjusting the weight ratio and overall solvent content, the patent maintains electrode performance while using non-toxic alternative solvents, thus resolving the contradiction between safety and reliability.
Solution Approach 2:
The patent uses the DMC-EMC solvent mixture as an intermediary substance that facilitates the binding of PVDF to electrode materials without the harmful effects of NMP. This intermediary solvent system mediates between the requirement for strong adhesion and the need for non-toxic materials, resolving the technical contradiction.
3Object-affected harmful factors
If the solvent system composition is changed to eliminate NMP, then environmental compatibility is improved, but manufacturing process compatibility may deteriorate
Solution Approach 1:
The patent adjusts the physical parameters of the solvent system, specifically the volatility and viscosity characteristics of DMC-EMC mixtures, to match the requirements of existing manufacturing processes. By optimizing these parameters within the allowed range of compositions, the patent ensures environmental compatibility while maintaining ease of manufacture.
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 proposed solution provides a non-toxic solvent system that maintains the necessary properties for electrode performance, ensuring effective adhesion and interconnectivity of electrochemically active materials, thus supporting the durability and efficiency of electrical storage devices.
Implementation Method 1
the PVDF fluoropolymer is dissolved in an organic solvent and the electrode material is combined with the solution to form a slurry that is applied to a metal foil or mesh to form the electrode. The role of the organic solvent is to dissolve the fluoropolymer in order to provide good adhesion between the electrode material particles and the metal foil or mesh
Implementation Method 2
the role of the organic solvent is to dissolve the fluoropolymer in order to provide good adhesion between the electrode material particles and the metal foil or mesh upon evaporation of the organic solvent
Data Source
AI summary
The present invention provides a binder composition comprising (a) at least one fluoropolymer comprising the residue of vinylidene fluoride; and (b) a solvent system comprising (i) a trialkyl phosphate; and (ii) a co-solvent comprising a lactone and/or a molecule comprising a sulfoxide and/or sulfone functional group; wherein the trialkyl phosphate and the co-solvent together comprise at least 50% by weight of the solvent system, based on the total weight of the solvent system. Also disclosed are slurry compositions, electrodes, and electrical storage devices.