Solid-State Battery Cathode Binder System for Adhesion and Dispersibility
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Solution Overview
Problem
Sulfide-based solid electrolytes in all-solid-state batteries face challenges with poor dispersibility and adhesion when using non-polar solvents, leading to inadequate performance in terms of ionic conductivity and energy density.
Innovation Solution
A positive electrode comprising a combination of two binders with different molecular weights, one long-chain and one short-chain binder with a thiol group, is used to enhance dispersibility and adhesion in a solvent-free process, ensuring superior adhesive strength and high-rate discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide-based solid electrolytes are used in all-solid-state batteries, then ionic conductivity and energy density are improved, but dispersibility and adhesion deteriorate due to side reactions with polar solvents
Solution Approach 1:
The patent introduces a non-polar solvent as an intermediary medium to process sulfide-based solid electrolytes. This solvent acts as a mediator that prevents direct contact between the sulfide electrolyte and polar solvents, thereby avoiding side reactions while enabling effective dispersing and binding of electrode components during manufacturing
Solution Approach 2:
The patent changes the solvent parameter from polar to non-polar type. By selecting binders and solvents with appropriate polarity characteristics (non-polar), the patent creates compatible processing conditions for sulfide-based solid electrolytes, improving dispersibility and adhesion without compromising ionic conductivity
2Reliability
If sulfide-based solid electrolytes are used in all-solid-state batteries, then energy density is improved, but adhesive strength deteriorates due to poor interfacial adhesion
Solution Approach 1:
The patent changes the molecular weight parameter of binders to optimize adhesion. By using a combination of high molecular weight binder (≥300,000 g/mol) and low molecular weight binder (≤50,000 g/mol), the patent achieves both mechanical strength and interfacial adhesion necessary for maintaining energy density performance
Solution Approach 2:
The patent employs a composite binder system combining two different binder materials with complementary properties. The high molecular weight binder provides structural framework and mechanical strength, while the low molecular weight binder enhances interfacial adhesion to sulfide electrolyte particles, collectively improving adhesive strength without sacrificing energy density
3Ease of manufacture
If conventional single binder system is used, then manufacturing is simpler, but dispersibility and adhesive strength are insufficient
Solution Approach 1:
The patent segments the binder function into two distinct components with different molecular weights. This segmentation allows each binder to perform its specialized function - the high molecular weight binder for structural integrity and the low molecular weight binder for interfacial bonding - thereby achieving superior adhesive strength while maintaining manufacturability through established coating processes
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 electrode exhibits improved dispersibility, adhesive strength, and capacity retention, resulting in enhanced performance of all-solid-state batteries.
Implementation Method 1
the second binder includes a thiol group
Data Source
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AI summary
The present invention relates to a positive electrode, a manufacturing method therefor, and an all-solid-state battery including same, wherein the positive electrode includes a positive electrode active material layer, the positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, and a binder, the binder includes a first binder having a weight average molecular weight of 300,000 g/mol or more and a second binder having a weight average molecular weight of 50,000 g/mol or less, and the second binder includes a thiol group. According to the present invention, it is possible to provide: the positive electrode having excellent adhesion between interfaces and/or between components in the positive electrode active material layer as well as excellent dispersibility, and having excellent high-rate discharge efficiency at 1.0C and capacity retention across cycles; a manufacturing method for the positive electrode; and an all-solid-state battery having excellent performance by including the positive electrode.