Patterned Binder Coating for Lithium Ion Battery Electrodes
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Solution Overview
Problem
Conventional lithium ion secondary battery manufacturing methods face challenges in achieving high production efficiency, reduced size, and increased capacity due to issues like active material and binder detachment during drying, leading to reduced electrode service life and inefficient solvent use.
Innovation Solution
A method involving pattern coating of a binder on a collector to create coated and uncoated sections, allowing for the deposition of a mix layer with active material and binder, which reduces penetration resistance and maintains high peel strength by eliminating the need for separate drying processes and solvent evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder solution is applied over the entire collector surface, then the bonding strength between collector and active material is improved, but the penetration resistance increases due to the insulating binder film
Solution Approach 1:
The collector surface is divided into coated sections with binder and uncoated sections without binder. This segmentation allows the binder to provide bonding strength only where needed, while leaving other areas open for direct contact between active material and collector, thus reducing penetration resistance while maintaining adequate bonding strength.
Solution Approach 2:
Different regions of the collector surface are given different properties: coated sections have binder for bonding, while uncoated sections have direct metal surface for low resistance contact. This local differentiation optimizes both bonding strength and penetration resistance by placing each material property where it is most needed.
2Manufacturing precision
If conventional coating method with solvent evaporation is used, then the paste can be applied in thin-film form, but the active material and binder detach during drying process
Solution Approach 1:
The harmful drying process that causes detachment is completely removed from the manufacturing method. Instead of applying paste and evaporating solvent, the invention uses direct deposition of powder mixture onto binder-coated sections, eliminating the drying step that causes active material and binder to detach.
Solution Approach 2:
The thermal drying process is replaced with a mechanical deposition and pressing process. The powder mixture is deposited and then pressed into the binder layer, using mechanical pressure instead of thermal energy to achieve proper adhesion, thereby avoiding the detachment problem caused by heat-induced solvent evaporation.
3Strength
If separate drying processes are required for first layer and second layer, then the bonding strength is improved, but the drying equipment size increases and production efficiency decreases
Solution Approach 1:
The coating and bonding processes are merged into a single step. The binder is applied to the collector, and the active material powder is deposited and pressed simultaneously, achieving both coating and bonding in one operation rather than requiring separate drying processes for multiple layers.
Solution Approach 2:
The binder is applied in advance to the collector surface in a patterned manner, creating prepared sections that will receive the active material. This preliminary action allows the subsequent deposition and pressing to proceed efficiently without requiring separate drying steps, improving production speed while maintaining bonding strength.
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
This method enhances production efficiency, reduces penetration resistance, and maintains high peel strength, enabling the production of lithium ion secondary batteries with improved performance and reduced costs.
Implementation Method 1
an intaglio gravure roll incised with a plurality of groove-shaped depressions having intersections where the grooves intersect with each other, a binder coating liquid supplied to the groove-shaped depressions shrinks to the intersections
Implementation Method 2
a binder coating liquid supplied to the groove-shaped depressions shrinks to the intersections
Implementation Method 3
the deposited layer of the binder solution and powder component on the collector is heated and pressurized by rollers
Data Source
AI summary
A method for manufacturing a lithium ion secondary battery having electrodes in which a mix layer including a first binder and one of a positive electrode active material and a negative electrode active material is formed via a second binder on a collector. The method includes: performing pattern coating of the second binder on the surface of the collector and regularly forming binder-coated sections and uncoated sections; and feeding a powder of mix particles on the binder-coated sections and the uncoated sections so as to form the mix layer on the collector.