Solid-State Battery Binder Composition for High-Temperature Cycling
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Solution Overview
Problem
Conventional binder compositions for all-solid-state secondary batteries do not adequately enhance output characteristics and high-temperature cycle characteristics, necessitating the development of a more effective binder solution.
Innovation Solution
A binder composition comprising a polymer with a nitrile group-containing monomer unit and an aliphatic conjugated diene monomer unit, within specific proportion ranges, and having a Mooney viscosity of 65 or more, is used to form a solid electrolyte-containing layer, along with a solvent like xylene or butyl butyrate, to improve adhesiveness and flexural resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional binder composition containing a polymer with nitrile group-containing polymerization unit is used, then the battery can be formed with basic binding function, but the output characteristics and high-temperature cycle characteristics are not sufficiently improved
Solution Approach 1:
The patent applies parameter changes by precisely controlling the nitrile group-containing polymerization unit content within 2-30 mass% range and the iodine value within 0-30 mg/100mg range. These specific parameter ranges optimize the binder's performance to simultaneously achieve good adhesion, flexural resistance, and high-temperature cycle characteristics without excessive formulation complexity
Solution Approach 2:
The patent uses composite materials by combining the nitrile group-containing polymer with specific additives including conductive agents and solid electrolytes in the slurry composition. This composite approach enhances output characteristics and high-temperature cycle performance while maintaining manageable formulation complexity through standardized component selection
2Power
If the polymer has high iodine value to improve output characteristics, then the binder performance is enhanced, but the manufacturing precision of the solid electrolyte-containing layer becomes more difficult to control
Solution Approach 1:
The patent applies parameter changes by limiting the iodine value to a specific range of 0-30 mg/100mg. This parameter control ensures the polymer has sufficient binding capability and adhesion while maintaining manageable viscosity and processability during slurry preparation and layer formation, thus balancing output characteristics with manufacturing precision
Solution Approach 2:
The patent applies partial action by using moderate iodine values (not excessively high) within the 0-30 mg/100mg range. This partial approach provides sufficient binder performance for good adhesion and flexural resistance without the diminishing returns and processing difficulties associated with very high iodine values, thereby maintaining layer formation precision
Data Source
AI summary
Provided is a binder composition for an all-solid-state secondary battery with which it is possible to form a solid electrolyte-containing layer that can cause an all-solid-state secondary battery to display excellent output characteristics and high-temperature cycle characteristics. The binder composition contains a polymer A that includes a nitrile group-containing monomer unit and an aliphatic conjugated diene monomer unit. The proportional content of the nitrile group-containing monomer unit in the polymer A is not less than 5 mass % and not more than 30 mass %, and the proportional content of the aliphatic conjugated diene monomer unit in the polymer A is not less than 40 mass % and not more than 95 mass %. The polymer A has a Mooney viscosity (ML1+4, 100° C.) of 65 or more.