Electrode Manufacturing via Substrate Stretching and Protective Layer
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Solution Overview
Problem
The existing methods for manufacturing electrodes, such as those for nonaqueous electrolyte secondary batteries, face challenges in achieving high packing density and reliability due to creases and warpage caused by uneven compression, and the active material layer being damaged or separated from the substrate during stretching processes.
Innovation Solution
A method involving the formation of a protective layer on the substrate edges followed by stretching these regions before compression, which prevents creases and warpage, and includes using a binder-rich protective layer to maintain the active material layer's integrity during stretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is compressed at higher pressure to increase packing density, then the volume energy density is improved, but the substrate is rolled and creases/warpage occur due to uneven compression between the active material layer region and exposed substrate regions
Solution Approach 1:
The exposed regions of the substrate are stretched in advance before the active material layer is formed and before compression. This preliminary stretching pre-compensates for the substrate, so that during subsequent compression, both the active material layer region and exposed substrate regions are compressed uniformly, preventing creases and warpage while achieving high packing density
Solution Approach 2:
Different regions of the substrate are treated differently: the exposed regions are stretched to a greater extent than the region where the active material layer will be formed. This local differentiation in stretching degree ensures that during compression, both regions compress uniformly without causing warpage, while the active material layer region achieves the required high packing density
2Manufacturing precision
If the exposed regions of the substrate are stretched before compression to prevent creases, then the flatness is improved, but the active material layer may be damaged or separated from the substrate during stretching
Solution Approach 1:
A protective layer is formed on the substrate in the exposed regions before the stretching step. This protective layer acts as a buffer that prevents direct mechanical stress from damaging the active material layer during subsequent stretching and compression operations, thereby maintaining both flatness and layer integrity
Solution Approach 2:
The protective layer serves as an intermediary between the stretching mechanism and the active material layer. It absorbs and distributes the mechanical stress during stretching, preventing direct contact and potential damage to the active material layer while still allowing the substrate to be stretched sufficiently to prevent creases
Data Source
AI summary
Disclosed is a method for manufacturing a positive electrode including a positive electrode substrate made of aluminum foil and a positive electrode active material layer containing a positive electrode active material on the positive electrode substrate. This method includes the steps of forming the positive electrode active material layer on the positive electrode substrate; forming a protective layer on the positive electrode substrate; stretching an exposed region of the positive electrode substrate after the steps of forming the active material layer and the protective layer; and compressing the positive electrode active material layer after the stretching step.