All-solid-state Battery Binder Composition for Low Temperature Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
All-solid-state lithium secondary batteries exhibit insufficient battery capacity and cycle characteristics due to inadequate ion conductivity in the solid electrolyte and active material layers, necessitating an improvement in binder composition for enhanced performance.
Innovation Solution
A binder composition for all-solid-state batteries comprising a copolymer with an alkylene structural unit and a nitrile group-containing monomer unit, combined with an ester compound or carbonate compound, is developed, optimizing the content ratio and iodine value to enhance flexibility and low temperature output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer solid electrolyte is used, then ion conductivity is improved, but safety deteriorates due to combustibility
Solution Approach 1:
The patent uses a composite binder system combining polyacrylonitrile (PAN) with polyvinylidene fluoride (PVDF) or carboxymethyl cellulose (CMC). This composite approach allows the binder to effectively bind inorganic solid electrolyte particles while maintaining flexibility and improving low-temperature performance, without introducing combustibility issues associated with polymer electrolytes.
2Object-affected harmful factors
If an inorganic solid electrolyte is used, then safety is improved, but ion conductivity deteriorates compared to polymer electrolytes
Solution Approach 1:
The patent optimizes the molecular weight of PAN binder within the range of 10,000-1,000,000 and controls the content ratio of nitrile group-containing monomer units at 10-55 mass%. These parameter optimizations enhance the binder's ability to maintain contact between inorganic solid electrolyte particles, thereby improving ion conductivity while preserving the safety advantages of inorganic materials.
3Ease of operation
If the nitrile group-containing monomer unit content is increased, then flexibility is improved, but binding ability deteriorates
Solution Approach 1:
The patent identifies an optimal range for nitrile group-containing monomer unit content at 10-55 mass% of total monomer units. Within this range, the binder achieves balanced performance where sufficient flexibility is maintained while adequate binding ability is preserved for holding inorganic solid electrolyte particles.
4Reliability
If the iodine value is increased, then low temperature output characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent specifies an iodine value range of 3-30 mg/100mg for the copolymer binder. This parameter control ensures adequate flexibility and low-temperature performance without requiring excessive unsaturation that would complicate manufacturing processes.
Data Source
AI summary
The present invention includes: a copolymer including alkylene structure units and nitrile-group-containing monomer units; and a carbonate compound and/or an ester compound having a boiling point of 100°C or higher and a molecular weight of 550 or less.