Lithium-Sulfur Positive Electrode Pressing for High-Solid Slurry Coating
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Solution Overview
Problem
The existing methods for manufacturing positive electrodes for lithium-sulfur batteries face challenges such as slow production speed due to long drying times for low solid concentration slurries, and difficulties in processing high solid concentration slurries due to lack of flowability, which affects the bonding force and surface characteristics of the electrodes.
Innovation Solution
A method involving a pressing process using a roll press is applied to manufacture positive electrodes from slurries with high solid concentrations (50-70 wt.%), which improves the adhesive force and surface characteristics by forming a bridging bond between positive electrode active materials, while reducing the drying time and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a slurry of positive electrode active material with low solid concentration is used, then the coating process is easy to perform, but the drying time is long and production speed is slow
Solution Approach 1:
The patent changes the solid concentration parameter of the slurry from conventional low levels to high levels (50-70 wt%), which fundamentally alters the coating and drying process characteristics. This parameter change enables shorter drying times and higher production speeds while maintaining coating quality through the use of a press during the coating process.
2Productivity
If a slurry of positive electrode active material with high solid concentration is used, then the drying time is reduced and production speed is improved, but the slurry lacks flowability and is difficult to manufacture through existing coating processes
Solution Approach 1:
The patent applies a press to the slurry during the coating process as a preliminary action to ensure proper distribution and adhesion before drying. This preliminary mechanical action compensates for the poor flowability of high solid concentration slurry, enabling successful coating without requiring the slurry to flow freely.
3Strength
If a slurry with high solid concentration is used, then the bonding force between positive electrode active materials is improved, but the surface characteristics and uniformity are affected
Solution Approach 1:
The press applied during coating performs a preliminary compaction action that ensures uniform distribution of the high solid concentration slurry and creates consistent surface characteristics before drying. This preliminary mechanical action prevents surface irregularities that would otherwise result from the poor flowability of the concentrated slurry.
4Reliability
If the drying process time is extended to ensure proper drying of low solid concentration slurry, then the quality is maintained, but the manufacturing cost increases
Solution Approach 1:
The patent changes the solid concentration parameter to high levels (50-70 wt%), which reduces the amount of solvent that needs to be evaporated. This parameter change directly reduces drying time and energy consumption while maintaining electrode quality, thereby reducing manufacturing costs.
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 proposed method enhances the adhesive force and surface smoothness of the positive electrodes, prevents non-uniform growth of the negative electrode and dendrite formation, and improves the production speed and efficiency of the lithium-sulfur battery manufacturing process.
Implementation Method 1
A method involving a pressing process using a roll press is applied to manufacture positive electrodes from slurries with high solid concentrations
Implementation Method 2
forming a bridging bond between positive electrode active materials, while reducing the drying time and cost
Implementation Method 3
The positive electrode can be prepared by first adding a binder and a solvent to the positive electrode active material to prepare a slurry of the positive electrode active material in a fluid form, and then coating the slurry on a current collector and drying it
Data Source
AI summary
Disclosed is a positive electrode for a lithium-sulfur battery, including a current collector; and a positive electrode active material layer on the current collector, wherein the positive electrode active material layer includes a positive electrode active material and a binder, and the positive electrode active material layer has surface properties defined by the following Sa (arithmetic mean surface roughness of the positive electrode) and Sz (maximum height roughness of the positive electrode) ((i) 1 μm≤Sa≤5 μm, (ii) 10 μm≤Sz≤60 μm (wherein Sa is the average value of the distance from the middle surface of the surface irregularity structure of the positive electrode to the highest point and the lowest point of each irregularity part, and Sz means the distance from the lowest point to the highest point of the positive electrode)) and a method for manufacturing the same.