Electrode Porosity Uniformity via Segmented Pressing
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Solution Overview
Problem
Electrodes for electrochemical devices often exhibit non-uniform porosity along their thickness direction due to uneven pressure distribution during the pressing process, leading to poor electrolyte impregnation and ion transport, which affects battery performance and lifespan.
Innovation Solution
A method involving the use of two types of electrode slurries with different particle sizes and structures, where the second slurry with smaller, primary particles is applied on top of the first slurry with larger, secondary particles, followed by partial removal of the surface layer after pressing, to achieve uniform porosity throughout the electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the electrode surface is pressurized more severely during the pressing process, then the thickness uniformity is improved, but the porosity near the electrode surface decreases
Solution Approach 1:
The pressing process is segmented into two distinct stages: a first pressing process that applies higher pressure to achieve thickness uniformity, and a second pressing process that applies lower pressure to preserve porosity. This segmentation allows each pressing stage to serve a specific function, resolving the contradiction between thickness uniformity and porosity uniformity.
Solution Approach 2:
The first pressing process is performed as a preliminary action to establish thickness uniformity before the second pressing process. By pre-establishing the thickness foundation, the subsequent second pressing can focus on maintaining porosity without compromising thickness uniformity, thus resolving the contradiction.
2Manufacturing precision
If the electrode surface is pressurized more severely during the pressing process, then the thickness uniformity is improved, but the electrolyte impregnation becomes difficult
Solution Approach 1:
The pressing process is divided into two stages with different pressure levels. The first stage ensures thickness uniformity, while the second stage maintains sufficient porosity for electrolyte impregnation. This segmentation resolves the contradiction between thickness uniformity and electrolyte impregnation.
Solution Approach 2:
The pressure parameter is changed between two pressing stages: high pressure in the first stage for thickness uniformity, and low pressure in the second stage for porosity preservation. This parameter change enables both thickness uniformity and electrolyte impregnation to be achieved.
3Quantity of substance
If the electrode density is increased, then the energy density is improved, but the porosity uniformity deteriorates
Solution Approach 1:
The two-stage pressing process segments the density control: the first stage increases overall density for energy density, while the second stage carefully controls the pressing to maintain porosity uniformity. This segmentation allows high energy density without sacrificing porosity uniformity.
Solution Approach 2:
The pressure parameter is optimized in two stages: high pressure to achieve high density and energy density, followed by a lower pressure stage to maintain porosity uniformity. This parameter change strategy resolves the contradiction between energy density and porosity uniformity.
Data Source
Figure 1~2a
Figure 2b~2e
Figure 3~6
AI summary
The present disclosure relates to an electrode for an electrochemical device and a method for manufacturing the same. More particularly, the present disclosure relates to an electrode having a small difference in porosity along the thickness direction of the electrode, and a method for manufacturing the same.