Binder for all-solid-state batteries, method for manufacturing the same, electrode for all-solid-state batteries containing said binder, and all-solid-state battery comprising said electrode

Sulfur-Crosslinked 3D Network Rubber Binder Compatible with Sulfide Electrolytes for All-Solid-State Batteries

This technology forms a 3D network structure through covalent bonding between carbon and sulfur within polymer chains. By mixing polymers containing unsaturated carbon double bonds with sulfur donors, vulcanization accelerators, and activators (ZnO, stearic acid) and applying heat treatment, the binder achieves superior mechanical properties and compatibility with sulfide-based solid electrolytes.

Conventional rubber-based binders often suffer from delamination from the substrate or electrode cracking during the drying process, and they fail to sufficiently suppress the expansion and contraction of active materials. Standard crosslinking methods also have limitations, as they can cause polar interactions that damage sulfide-based solid electrolytes.

This technology utilizes a vulcanization system that introduces sulfur into unsaturated polymers, such as butadiene rubber, to create a covalent-bond-based 3D network. By maintaining a Raman intensity ratio of polysulfide to disulfide bonds between 1.1 and 3.1, the structure prevents damage to the solid electrolyte while enhancing electrode durability and oxidation stability. Applicable to the manufacturing of cathode/anode mixtures and solid electrolyte sheets for sulfide-based all-solid-state batteries, it allows for the use of existing rubber processing materials and non-polar solvents while reducing cracking and peeling in large-area electrodes.

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Key Features:

• Binder composition comprising 100 parts by weight of a polymer with unsaturated carbon double bonds and 1 to 30 parts by weight of a sulfur donor
• Vulcanization additives including 0.5 to 4 parts by weight of a vulcanization accelerator, 3 to 10 parts by weight of a ZnO-based primary activator, and 1 to 4 parts by weight of a stearic acid secondary activator
• Binder for all-solid-state batteries featuring a 3D network structure formed by carbon-sulfur covalent bonds via heat treatment
• Crosslinked structure with a Raman intensity ratio of polysulfide to disulfide bond peaks between 1.1 and 3.1

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This invention was developed with support from the Ministry of Science and ICT for the development of core technologies for R2R-type high-ionic-conductivity functional solid-state electrolyte membranes.

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