Cathode Slurry Composition With Dual-Solvent Binder Dispersion
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Solution Overview
Problem
The development of all-solid-state batteries is hindered by the challenge of achieving high energy density, as existing high-adhesion binders do not dissolve well in solvents compatible with sulfide-based solid electrolytes, leading to difficulties in dispersing cathode active materials and solid electrolytes.
Innovation Solution
A cathode slurry composition using a complex solvent system, comprising a first solvent that dissolves a rubber-based binder with a polar functional group and a second solvent that disperses the cathode active material and solid electrolyte, where the Hansen parameter value δd of the first solvent ranges from 19 to 25 MPa1/2.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a high-adhesion binder is used to thicken the cathode, then adhesion of the mixture-substrate interface is improved, but the binder does not dissolve well in solvents compatible with sulfide-based solid electrolytes
Solution Approach 1:
The patent changes the chemical parameters of the binder by introducing polar functional groups (carboxyl, hydroxyl, or epoxy groups) into the rubber-based binder structure. This modification enables the binder to dissolve in solvents with higher polarity that are compatible with sulfide-based solid electrolytes, while maintaining high adhesion properties. The specific parameter change in the binder's molecular structure resolves the contradiction between adhesion and dissolvability.
2Reliability
If a solvent with low polarity is used to disperse cathode active material and solid electrolyte, then compatibility with sulfide-based solid electrolyte is improved, but high-adhesion binder cannot dissolve
Solution Approach 1:
The patent changes the polarity parameter of the solvent from low polarity to higher polarity range (Hansen parameter δp: 5-15 MPa1/2), which enables both the modified rubber-based binder with polar functional groups to dissolve and maintains compatibility with sulfide-based solid electrolytes. This parameter adjustment in the solvent resolves the contradiction between compatibility and dissolvability.
3Quantity of substance
If cathode thickness is increased to increase energy density, then energy density is improved, but uniform dispersion of cathode active material and solid electrolyte becomes difficult
Solution Approach 1:
The patent uses a composite solvent system comprising multiple components with different Hansen parameters, creating a synergistic effect that enhances the dispersion of cathode active material and solid electrolyte throughout the cathode mixture. This composite approach ensures uniform distribution even in thickened cathodes, resolving the contradiction between energy density and dispersion uniformity.
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 enhances the adhesion between the cathode mixture and the substrate, improves the dispersibility of cathode active materials and solid electrolytes, and reduces electrode resistance, thereby increasing the energy density of all-solid-state batteries.
Implementation Method 1
a first solvent capable of dissolving the rubber-based binder
Implementation Method 2
a second solvent capable of dispersing the cathode active material and the solid electrolyte
Data Source
AI summary
A cathode slurry composition for an all-solid-state battery includes a rubber-based binder containing a polar functional group, a cathode active material, a solid electrolyte, and a complex solvent. The complex solvent contains a first solvent capable of dissolving the rubber-based binder and a second solvent capable of dispersing the cathode active material and the solid electrolyte. A Hansen parameter value δd of the first solvent is in a range from 19 to 25 MPa1/2. A method for preparing the same is provided. A cathode for an all-solid-state battery manufactured from the cathode slurry composition and an all-solid-state battery includes the same.