Dry Electrode Sheet Lamination for Higher Tensile Strength
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Solution Overview
Problem
The manufacturing of lithium secondary battery electrodes faces issues with surface defects and decreased binding force due to solvent evaporation and particle migration, and the dry electrode method lacks sufficient tensile strength, necessitating a method to improve electrode quality and manufacturing processability without drying.
Innovation Solution
A dry electrode sheet manufacturing method involving a calendering process with a calender roll, cutting, and laminating operations to form a sheet with a fibrous binder, which provides improved tensile strength and density without the need for a drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a drying process is used to evaporate solvent from electrode mixture slurry, then the electrode sheet can be formed, but surface defects occur and particle migration causes decreased binding force
Solution Approach 1:
The invention extracts and eliminates the drying process from the electrode manufacturing sequence. By using a dry electrode mixture without solvent, the harmful evaporation step is completely removed, preventing both surface defects and particle migration while maintaining manufacturing efficiency
Solution Approach 2:
The invention changes the fundamental parameter of electrode mixture composition by eliminating solvent entirely. This parameter change transforms the manufacturing approach from wet to dry processing, resolving the contradictions caused by solvent evaporation while enabling new processing methods
2Productivity
If a dry electrode manufacturing method is used without solvent, then the drying process can be omitted, but the electrode sheet lacks sufficient tensile strength and cracks occur
Solution Approach 1:
The invention uses composite material structure by combining dry electrode mixture particles with a specific binder composition. This composite approach provides sufficient tensile strength and cohesion to the electrode sheet while maintaining the dry processing advantage, preventing cracks during handling
Solution Approach 2:
The invention performs preliminary binding action by carefully selecting and preparing the binder material before electrode formation. The binder is pre-configured to provide adequate tensile strength and cohesion, allowing the dry electrode sheet to maintain structural integrity without requiring subsequent drying or additional strengthening steps
3Manufacturing precision
If conventional drying apparatuses are used to control solvent evaporation rate, then uniform drying can be achieved, but the equipment cost and operation time increase significantly
Solution Approach 1:
The invention extracts and eliminates the complex drying apparatus entirely from the manufacturing system. By adopting dry electrode processing, all expensive drying equipment and associated operational complexities are removed, achieving the goal with simpler, more cost-effective equipment
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 method produces a dry electrode sheet with enhanced tensile strength and density, maintaining the sheet shape and improving manufacturing efficiency by eliminating the solvent drying step.
Implementation Method 1
calendering the dry electrode composition with a calender roll and forming a first electrode sheet
Implementation Method 2
a binder, which may be a fiberizable binder
Implementation Method 3
the binder may be at least one selected from the group consisting of polytetrafluoroethylene, polyethylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, and cellulose derivatives
Implementation Method 4
laminating and then calendering the cut first electrode sheet
Data Source
AI summary
A method of manufacturing a dry electrode sheet for a secondary battery includes providing a dry electrode composition comprising an active electrode material and a binder, calendering the dry electrode composition with a calender roll and forming a first electrode sheet, cutting the first electrode sheet into two or more pieces, and laminating and then calendering the cut first electrode sheet.