Lithium Cathode Washing for Low-Viscosity Slurry Coating
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Solution Overview
Problem
High amounts of residual lithium species in lithium-ion battery cathode active materials can lead to increased viscosity and gelation of the cathode slurry, making it difficult to coat onto current collectors and resulting in poor cell performance.
Innovation Solution
A washing process is employed to reduce the amount of residual lithium species in the cathode active material, involving exposure to a liquid that dissolves the residual lithium, followed by separation and drying to produce a washed cathode material with lower residual lithium content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cathode active materials with residual lithium species are used, then the material can be easily prepared, but the cathode slurry viscosity increases and gelation occurs, making coating difficult
Solution Approach 1:
The patent applies preliminary action by performing a washing process on the cathode active material before slurry preparation. This pre-treatment removes residual lithium species (LiOH and Li2CO3) from the material surface, preventing subsequent slurry gelation and coating difficulties. The washing step is conducted ahead of time to eliminate harmful residues that would otherwise interfere with later processing steps.
Solution Approach 2:
The patent converts the harmful effect of residual lithium species into a benefit by using these residues as indicators for necessary processing. The presence of LiOH and Li2CO3 residues, which normally cause gelation, is transformed into an opportunity to apply a washing treatment that improves overall cathode performance. The harmful residues become a focal point for quality improvement through targeted removal.
2Productivity
If cathode active material with residual lithium species is used, then the material can be directly processed, but the cell performance deteriorates
Solution Approach 1:
The washing process is implemented as a preliminary action before cathode fabrication to remove residual lithium species. This pre-treatment ensures that the material is properly prepared, preventing subsequent performance issues while maintaining efficient processing. The step is integrated into the workflow to ensure both productivity and reliability.
Solution Approach 2:
The residual lithium species, which normally degrade cell performance, are converted into a beneficial processing control point. By identifying and removing these residues through washing, the patent transforms a performance-destroying element into an opportunity for quality enhancement, ensuring both high productivity and reliable cell performance.
3Ease of operation
If washing process is applied to remove residual lithium species, then the cathode slurry processability improves, but additional processing steps are required
Solution Approach 1:
The patent applies the extraction principle by removing residual lithium species (LiOH and Li2CO3) from the cathode active material through a washing process. This extraction of harmful components simplifies the overall processing by preventing gelation and coating failures, making the slurry preparation more reliable despite adding a washing step.
Solution Approach 2:
The washing process changes the chemical composition parameter of the cathode active material by removing residual lithium species. This parameter change improves slurry rheology and coating performance. The additional processing step is justified by the significant improvement in processability and final product quality.
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 washing process effectively reduces the residual lithium species in the cathode active material, improving the processability of the cathode slurry and enhancing the electrochemical performance of the lithium-ion battery.
Implementation Method 1
exposing the lithium-based cathode material to a liquid, such as where at least a portion of the residual lithium species dissolves in the liquid
Implementation Method 2
The separating process may use any desirable techniques. Example separating techniques include, but are not limited to, one or more of a filtration process, a centrifuging process, or a decanting process.
Implementation Method 3
The separating process may use any desirable techniques. Example separating techniques include, but are not limited to, one or more of a filtration process, a centrifuging process, or a decanting process.
Implementation Method 4
drying the lithium-based cathode material
Data Source
AI summary
Techniques for processing lithium-ion cathode active materials, such as cathode active materials comprising lithium-based materials, such as lithium metal oxide materials (e.g., lithium transition metal oxide materials) are provided. The techniques process the lithium-ion cathode active materials after an initial preparation step to remove residual lithium species, such as lithium hydroxide and/or lithium carbonate, present in the lithium-ion cathode active materials. Cathode materials comprising low residual lithium species are also described, as well as cathodes and batteries comprising such cathode materials.