Dry Electrode Binder Particles for Lithium-Ion Capacity and Adhesion
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Solution Overview
Problem
The existing methods for producing lithium ion secondary battery electrodes, particularly the wet method, require solvent volatilization steps that complicate the process, pose safety and environmental concerns, and necessitate complex parameter control for achieving desired film thickness and composition.
Innovation Solution
The development of an electrode binder comprising ultrahigh molecular weight olefinic polymer fine particles that can be used in a dry method for electrode fabrication, allowing for improved adhesiveness, reduced electrical defects, and enhanced charge/discharge capacity of lithium ion secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the wet method is used for electrode production, then the coating mass and film thickness can be controlled, but the process becomes complicated due to solvent volatilization steps and safety/environmental issues arise
Solution Approach 1:
The invention extracts and eliminates the solvent component from the electrode production process. By using a dry method without solvent, the patent removes the volatilization step and associated complexity while maintaining the ability to control coating mass and film thickness through direct powder compression molding.
Solution Approach 2:
The invention changes the physical state parameter of the binding medium from liquid (solvent-based slurry) to solid (powder form). This parameter change enables the transition from wet coating methods requiring volatilization to dry compression molding, simplifying the process while maintaining manufacturing precision.
2Manufacturing precision
If the wet method is used for electrode production, then the slurry can be coated on current collector, but complex parameter control is required for achieving desired composition
Solution Approach 1:
The invention performs preliminary mixing and size classification of the active material powder before compression molding. By pre-doping the powder with appropriate composition ratios and controlling particle size distribution in advance, the patent achieves desired composition without requiring complex parameter control during the coating process.
Solution Approach 2:
The invention replaces the chemical/viscositic control system of slurry coating with a mechanical compression system. Instead of controlling film thickness through slurry viscosity and coating parameters, the patent uses mechanical compression force and pressure distribution to achieve precise composition and thickness control, simplifying the fabrication process.
3Reliability
If conventional binders are used in dry method, then the electrode can be fabricated without solvent, but the charge/discharge capacity is insufficient
Solution Approach 1:
The invention changes the particle size parameter of the binder from conventional larger sizes to fine particles with specific size distribution (D50: 1-50 μm). This parameter change increases the surface area and contact points of the binder with active material particles, improving adhesiveness while maintaining high charge/discharge capacity through better electrical connectivity.
Solution Approach 2:
The invention uses a composite binder system consisting of ultrahigh molecular weight olefinic polymer fine particles combined with specific particle size distributions. This composite approach provides both strong mechanical adhesion and adequate electrical conductivity, resolving the trade-off between binder strength and battery capacity.
Data Source
AI summary
One embodiment of the present invention relates to an electrode binder, an electrode, a lithium ion secondary battery, or a method for producing the electrode, and the electrode binder includes an ultrahigh molecular weight olefinic polymer fine particle (A) that satisfies the following requirements (i) to (iii):(i) the intrinsic viscosity [η] measured in a decalin solvent at 135° C. is in a range of 5 to 50 dl/g;(ii) the average particle diameter d50 in a mass-based particle size distribution by a Coulter counter method is in a range of 1 to 50 μm; and(iii) 50% by mass or more of the particles passes through a mesh sieve with an opening of 45 μm.