Dry Electrode Sheet Calendering for Uniform Solvent-Free Battery Electrodes
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Solution Overview
Problem
Existing methods for preparing lithium secondary battery electrodes face issues such as solvent evaporation defects leading to pinholes or cracks, non-uniform drying, and high manufacturing costs due to the use of expensive drying devices.
Innovation Solution
A method involving a calendering process using a device with specific roll velocity and gap ratios to uniformly distribute electrode active materials, binders, and conductive materials, forming a self-standing dry electrode sheet.
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 mixture layer is formed, but defects such as pinholes or cracks occur and internal and external regions are not uniformly dried
Solution Approach 1:
The invention extracts and eliminates the drying process entirely from the electrode manufacturing process. By using a solvent-free electrode mixture composition, the patent removes the source of evaporation defects (pinholes, cracks, non-uniform drying) while maintaining electrode formation capability through direct calendering of the wet mixture.
Solution Approach 2:
The invention changes the fundamental parameter of solvent content from containing solvent to being completely solvent-free. This parameter change transforms the electrode mixture into a dry or low-moisture composition that can be directly calendered without drying, eliminating all drying-related defects while improving manufacturing precision.
2Manufacturing precision
If a drying device is used to control evaporation rate and ensure uniform drying, then electrode quality improves, but manufacturing cost and operation time increase significantly
Solution Approach 1:
The invention extracts and eliminates the expensive drying device from the manufacturing process by using a solvent-free composition. This removes the need for costly equipment while maintaining uniform electrode formation through direct calendering, thereby improving productivity without sacrificing manufacturing precision.
Solution Approach 2:
The invention replaces expensive, complex drying devices with a simple, cost-effective calendering process. By using a solvent-free composition that can be directly calendered, the patent eliminates the need for costly equipment investment and operation, significantly improving manufacturing efficiency.
3Manufacturing precision
If a drying process is used to form electrode mixture layer, then electrode structure is created, but manufacturing cost and operation time increase
Solution Approach 1:
The invention extracts and eliminates the time-consuming drying process by using a solvent-free electrode mixture composition. The electrode structure is formed directly through calendering of the wet mixture, completely removing the drying time step while maintaining structural integrity.
Solution Approach 2:
The invention performs preliminary mixing of the electrode mixture composition in a dry or low-moisture state before calendering. This preliminary preparation ensures proper material distribution and bonding characteristics, allowing direct calendering to form the electrode structure without subsequent drying time.
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 ensures uniform drying and improved electrode quality by evenly distributing materials, reducing manufacturing costs and time, and enhancing the electrode's tensile strength and conductivity.
Implementation Method 1
a rolling process in which the mixture layer is pressurized to form a predetermined thickness
Implementation Method 2
A temperature of the rolls may be greater than 50° C. and less than 120° C.
Implementation Method 3
the two rolls (Rna and Rnb) adjacent to each other and providing the nth inter-roll gap (Gn) have a velocity (V) ratio of 10% or more to less than 50%
Data Source
AI summary
The present disclosure provides a method for preparing a dry electrode sheet for a secondary battery by allowing a composition for preparing a dry electrode sheet including an electrode active material and a binder to pass through a calendering device, a dry electrode sheet for a secondary battery prepared therefrom and a calendering device used for preparation of a dry electrode sheet for a secondary battery.