Solid-State Battery Binder Composition for Soluble Adhesive Slurries
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Solution Overview
Problem
Existing binders for sulfide-based solid-state batteries have low solubility in solvents, limiting their effectiveness in forming electrodes and electrolyte layers, and do not provide adequate adhesion and flexibility.
Innovation Solution
A polymer binder comprising vinylidene fluoride units and specific fluorine-containing monomer units, with a molar ratio of 87/13 to 20/80, is used in a slurry with low-polarity solvents, expanding solvent options and ensuring excellent solubility, adhesion, and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders are used in sulfide-based solid-state batteries, then the battery structure is simple, but the solubility in solvents is low and adhesion is insufficient
Solution Approach 1:
The patent uses a copolymer binder composed of vinylidene fluoride units and fluorine-containing monomer units (formula 1 or 2), creating a composite material structure that combines the solubility benefits of vinylidene fluoride with the adhesion and flexibility benefits of the fluorine-containing units. This composite approach resolves the contradiction by achieving both good solubility in low-polarity solvents and adequate adhesion without requiring complex multi-component systems.
Solution Approach 2:
The patent optimizes the molar ratio of vinylidene fluoride units to fluorine-containing monomer units within the range of 87/13 to 20/80, and controls the glass transition temperature at 25°C or less. These parameter changes enable the binder to achieve both sufficient solubility in low-polarity solvents and adequate adhesion performance, resolving the contradiction between simple structure and functional performance.
2Reliability
If existing binders are used, then the manufacturing process is simple, but the flexibility and adhesion of the electrode are inadequate
Solution Approach 1:
The patent controls the glass transition temperature of the binder at 25°C or less and optimizes the monomer ratio to ensure flexibility while maintaining ease of manufacture. The specific chemical structure with fluorine-containing groups provides inherent flexibility without requiring additional plasticizers or complex processing steps.
Solution Approach 2:
The fluorine-containing monomer units act as intermediaries that bridge the polarity mismatch between the binder and low-polarity solvents, enabling good solubility and uniform slurry formation. This intermediary structure allows the binder to be processed in simple slurry preparations while achieving the desired flexibility and adhesion.
3Reliability
If conventional binders are used, then the solvent selection is limited, but the solubility is insufficient
Solution Approach 1:
The patent designs the binder with a glass transition temperature of 25°C or less and specific fluorine-containing groups that enhance compatibility with low-polarity solvents. This parameter optimization enables the binder to dissolve well in versatile low-polarity solvents such as esters, ethers, and hydrocarbons, resolving the contradiction between achieving good solubility and expanding solvent options.
Solution Approach 2:
The fluorine-containing monomer units provide universal compatibility across multiple classes of low-polarity solvents (esters, ethers, hydrocarbons), making the binder versatile and adaptable to different solvent systems. This multi-functionality resolves the contradiction by enabling good solubility across a wide range of solvent options rather than requiring a single specific 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 binder achieves satisfactory slurry formation for sulfide-based solid-state batteries with improved adhesion and flexibility, enhancing the performance and longevity of the battery.
Implementation Method 1
a binder used in a slurry for a solid-state battery comprising sulfide-based solid electrolyte particles, the binder being a polymer comprising: a vinylidene fluoride unit; and at least one copolymerization unit (A) selected from the group consisting of a monomer unit having a structure represented by formula (1) below and a monomer unit having a structure represented by formula (2) below
Data Source
AI summary
A binder and a slurry suitable for use in the production of an electrode in a sulfide-based solid-state battery. The binder contains sulfide-based solid electrolyte particles, and is a polymer including a vinylidene fluoride unit and at least one copolymerization unit (A) selected from a monomer unit having a structure represented by formula (1) below and a monomer unit having a structure represented by formula (2) below:where Rf1 and Rf2 are each a linear or branched fluorinated alkyl or fluorinated alkoxy group with 1 to 12 carbon atoms, which optionally contains an oxygen atom between carbon-carbon atoms when the number of carbon atoms is 2 or more. The slurry contains sulfide-based solid electrolyte particles, the binder and a solvent. Also disclosed is an electrode including an electrode active material layer formed using the slurry and a lithium-ion secondary solid state battery including the electrode.