Cathode Active Material Composition for Low-Viscosity Battery Slurry
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Solution Overview
Problem
The dispersion of cathode active material powder in secondary batteries is poor, leading to high slurry viscosity and defects such as cracks, stripes, and uneven weight during electrode plate preparation.
Innovation Solution
A cathode active material composition with a core-shell structure, including a core of Li1+xMn1−yAyP1−zRzO4 coated with multiple layers and a dispersant polymer, improves dispersion and reduces slurry viscosity, comprising a crystalline pyrophosphate, phosphate, and carbon coating layers, along with a hydrogenated nitrile butadiene rubber dispersant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cathode active material powder is used with large specific surface area and small particles, then energy density is improved, but dispersion becomes difficult and slurry viscosity increases
Solution Approach 1:
The patent introduces a dispersant as an intermediary substance to facilitate the dispersion of cathode active material powder in the slurry. The dispersant reduces particle-particle interactions and improves wetting, enabling better dispersion of fine particles without increasing viscosity excessively.
Solution Approach 2:
The patent modifies the slurry composition parameters by adding specific dispersants and adjusting the ratio of components. This changes the rheological properties of the slurry, reducing viscosity and improving flow characteristics while maintaining high solid content with fine particles.
2Use of energy by moving object
If cathode active material powder with small particles is used, then energy density is improved, but coating defects such as cracks, stripes, and pinholes increase
Solution Approach 1:
The dispersant acts as a mediator between the fine particles and the binding agents, ensuring uniform distribution and adhesion. This prevents coating defects by maintaining particle separation and promoting even deposition on the current collector.
Solution Approach 2:
The patent performs preliminary dispersion treatment of the cathode active material powder before slurry preparation. This pre-dispersion step prevents particle aggregation, ensuring uniform particle distribution in the slurry and eliminating coating defects during the electrode fabrication process.
3Productivity
If solid content of slurry is increased, then productivity is improved, but viscosity increases and dispersion becomes poorer
Solution Approach 1:
The patent changes the chemical composition parameters of the slurry by incorporating specific dispersants and adjusting the solvent-to-solids ratio. This allows achieving high solid content (improved productivity) while maintaining manageable viscosity through modified interfacial properties and reduced particle aggregation.
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 solution enhances the processing performance and battery performance by reducing manganese exsolution, improving cycling and safety performance, and maintaining electrical neutrality to minimize defects and heterogeneous phases.
Implementation Method 1
the dispersant includes a polymer
Implementation Method 2
the first coating layer includes a crystalline pyrophosphate MP2O7 and/or Mb(P2O7)c... the second coating includes a crystalline phosphate XPO4
Data Source
AI summary
Provided are a cathode active material composition, a cathode plate, a secondary battery, a battery module, a battery pack, and an electric device. In particular, the present application provides a cathode active material composition, including a cathode active material and a dispersant. The cathode active material composition of the present application can improve the poor dispersion of the cathode active material powder and the high viscosity of the slurry during the preparation of the cathode slurry, and further improve flexibility of the cathode plate.