Lithium Battery Electrode Extrusion Lamination Without NMP Solvents
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Solution Overview
Problem
Current methods for manufacturing lithium battery electrodes using organic solvents like N-methyl-2-pyrrolidone pose health and environmental risks, and result in electrode damage during solvent evaporation, necessitating the development of solvent-free or reduced-solvent processes for sustainable and cost-effective production.
Innovation Solution
A continuous process involving a surface-modified metal foil coated with a composition containing a semi-crystalline partially fluorinated polymer, a liquid medium with a high boiling point, and an electro-active compound, which is extruded and laminated to form a solvent-free electrode suitable for lithium batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic solvents like NMP are used to dissolve fluoropolymer binders and homogenize electrode components, then the electrode components can be properly bound together, but this causes health and environmental risks and requires solvent recycling
Solution Approach 1:
The invention extracts and eliminates the harmful organic solvent (NMP) from the electrode manufacturing process by using a water-based slurry formulation. The fluoropolymer binder is dispersed in water instead of dissolved in organic solvent, achieving binder functionality without the harmful extraction step that requires recycling infrastructure.
Solution Approach 2:
The invention changes the fundamental parameter of the liquid medium from organic solvent to water-based slurry. This parameter change transforms the manufacturing process from solvent-based to water-based, eliminating health and environmental risks while maintaining electrode structural integrity through proper slurry formulation and processing conditions.
2Strength
If high content of solvents is used in thick electrodes to ensure proper binding, then the electro-active material particles can be bound together, but this damages the electrode during solvent evaporation causing crack formation
Solution Approach 1:
The invention extracts the problematic evaporation step by using water as the liquid medium instead of organic solvent. Water can be removed by drying without the rapid phase change that causes cracking, and the water-based slurry allows for controlled drying processes that maintain electrode integrity while achieving proper binding strength.
Solution Approach 2:
The invention changes the liquid medium parameter from organic solvent to water, which fundamentally alters the drying behavior. Water's higher heat capacity and lower volatility compared to organic solvents enable controlled moisture removal that prevents crack formation in thick electrodes while maintaining adequate binder strength.
3Reliability
If traditional solvent casting process is used to manufacture electrodes, then good electrochemical performance can be achieved, but this requires expensive solvent recycling infrastructure and creates environmental burden
Solution Approach 1:
The invention extracts and eliminates the need for solvent recycling infrastructure by replacing organic solvents with water-based slurry. The water can be evaporated or separated without requiring complex recycling systems, thereby maintaining electrode performance while dramatically simplifying the manufacturing infrastructure.
Solution Approach 2:
The invention adopts a disposable water-based approach where water serves as a temporary carrier that is easily removed by evaporation or drying. This eliminates the need for expensive, long-lived solvent recycling infrastructure, as water can be discarded after serving its binding function during manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process produces high-performance electrodes with reduced environmental impact and eliminates the need for solvent recycling, maintaining electrochemical performance comparable to traditional methods.
Implementation Method 1
The polymer binder should properly bind the electro-active material particles together and to the metal collector so that these particles can chemically withstand large volume expansion and contraction during charging and discharging cycles
Implementation Method 2
providing an electrode-forming composition (C) comprising: from 0.5 wt. % to less than 20 wt. % of at least one semi-crystalline partially fluorinated polymer (F)... from 2 wt. % to less than 40 wt. % of at least one liquid medium (L) characterized by a boiling point higher than 100° C.
Implementation Method 3
extruding the mixed composition (C) obtained in step (iii) through a die opening at temperature comprised between 50 and 130° C. to provide a sheet of composition (C)
Implementation Method 4
laminating the sheet of composition (C) obtained in step (iv) to provide a sheet having a thickness in the range of from 50 to 300 microns
Implementation Method 5
depositing the sheet of composition (C) obtained in step (iv) or in step (v) onto at least one side of the surface-modified metal foil (M) provided in step (i), thereby providing an assembly comprising a surface-modified metal foil (F) having at least part of at least one side that is coated with a layer (L1) consisting of said composition (C)
Implementation Method 6
providing a surface-modified metal foil (M) having at least one side that is at least partially chemically modified
Data Source
AI summary
The present invention pertains to a continuous process for the manufacture of an electrode, to the electrode obtained therefrom and to an electrochemical device comprising said electrode.