Water-Based Binder for Lithium Battery Positive Electrode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The use of non-aqueous PVDF/NMP systems as electrode binders in lithium secondary batteries leads to environmental contamination, high manufacturing costs, and reduced battery stability due to low adhesive strength and fluoride-lithium reactions, while water-based binders face limitations in active material selection and corrosion issues.
Innovation Solution
A positive electrode for lithium secondary batteries incorporating lithium transition metal complex oxides, active carbon with a specific surface area of 900-1600 m2/g, and a water-based binder, which enhances binding strength, prevents corrosion, and maintains high capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PVDF/NMP non-aqueous system is used as binder, then adhesive strength is improved, but environmental contamination and manufacturing cost increase
Solution Approach 1:
The patent changes the fundamental parameter of the binder system from non-aqueous (PVDF/NMP) to aqueous-based, eliminating organic solvent contamination while maintaining adhesive strength through the synergistic combination of carboxymethyl cellulose and styrene-butadiene rubber binders in controlled ratios
Solution Approach 2:
The patent uses a composite binder system combining carboxymethyl cellulose (aqueous-based) with styrene-butadiene rubber, creating a hybrid material that leverages the environmental benefits of aqueous systems while retaining the high adhesive properties of rubber-based binders
2Strength
If PVDF/NMP non-aqueous system is used as binder, then adhesive strength is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive PVDF/NMP binder system with more economical carboxymethyl cellulose and styrene-butadiene rubber alternatives, reducing material costs while achieving sufficient adhesive performance for battery operation
Solution Approach 2:
The patent changes the binder chemistry from expensive fluoropolymer-based systems to more cost-effective cellulose and rubber-based systems, optimizing the balance between adhesive strength and manufacturing cost
3Strength
If PVDF/NMP non-aqueous system is used as binder, then binding strength is maintained, but battery stability decreases due to fluoride-lithium reactions
Solution Approach 1:
The patent eliminates the harmful fluoride-lithium reaction by removing PVDF containing C-F bonds, converting the stability problem into a solution by using fluorine-free binder materials that are chemically compatible with lithium ions
Solution Approach 2:
The patent changes the chemical composition parameter by eliminating fluorine-containing compounds from the binder system, preventing the formation of LiF and associated thermal runaway issues while maintaining adequate adhesive strength
4Object-affected harmful factors
If water-based binder system is used, then environmental friendliness and cost are improved, but adhesive strength decreases
Solution Approach 1:
The patent creates a composite binder system combining carboxymethyl cellulose (providing aqueous-based environmental benefits) with styrene-butadiene rubber (providing high adhesive strength), achieving both environmental friendliness and sufficient binding performance
Solution Approach 2:
The patent designs a multi-functional binder system where carboxymethyl cellulose provides aqueous compatibility and environmental benefits, while styrene-butadiene rubber contributes adhesive strength, making the single binder formulation accomplish multiple requirements simultaneously
Data Source
AI summary
A positive electrode for a lithium secondary battery is described which includes a lithium transition metal complex oxide including a lithium nickel based complex oxide and/or a lithium cobalt based complex oxide, active carbon having a specific surface area of from about 900 m2/g to about 1600 m2/g, and a water-based binder.