Positive Electrode Dry Coating for Low-Porosity Solid Electrolytes
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Solution Overview
Problem
The existing methods for preparing secondary batteries with solid electrolytes face limitations in productivity and mechanical stability due to the use of solvents, which lead to reduced energy density and porosity issues in the active material layer.
Innovation Solution
A method involving the formation of a solid electrolyte by mixing a lithium salt and a polymer in a dry atmosphere, followed by adding a conductive agent and positive electrode active material to create a dry mixture, and applying a shear force to form granules, which are then coated onto a current collector without the use of solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solvent is used to mix the solid electrolyte with electrode slurry, then the solid electrolyte can be uniformly distributed in the electrode, but the solid content of the electrode slurry is reduced and porosity increases
Solution Approach 1:
The invention extracts and eliminates the solvent from the electrode slurry system. By using a dry mixing process without any solvent, the solid electrolyte is directly mixed with the positive electrode active material and conductive agent in a dry state, thereby removing the harmful factor (solvent) that causes reduced solid content and increased porosity.
Solution Approach 2:
The invention changes the physical state parameter of the mixing process from wet (with solvent) to dry (without solvent). This parameter change allows the solid electrolyte to be uniformly distributed through dry mixing, maintaining high solid content and low porosity in the final electrode product.
2Productivity
If the drying temperature is increased to improve productivity, then the drying process is accelerated, but crystallization of the solid electrolyte occurs and unintended voids are formed
Solution Approach 1:
The invention extracts and eliminates the drying process entirely by using a dry mixing method from the beginning. Since no solvent is used, there is no drying required, thus avoiding the harmful effect of high-temperature drying that causes crystallization and void formation while maintaining high productivity.
Solution Approach 2:
The invention performs the mixing of solid electrolyte with electrode materials in a dry state before electrode formation, eliminating the need for subsequent drying. This preliminary dry mixing action prevents the need for high-temperature drying that would cause crystallization and voids, thereby maintaining manufacturing precision.
3Stability of the object's composition
If a solvent is used to prepare the electrode slurry, then the solid electrolyte can be mixed uniformly, but the thickness of the active material layer is excessively reduced and uniform thickness preparation is difficult
Solution Approach 1:
The invention extracts and eliminates the solvent from the slurry preparation process. By using dry mixing instead of wet mixing with solvent, the active material layer maintains its proper thickness without excessive reduction, while still achieving uniform distribution of solid electrolyte through the dry mixing process.
4Quantity of substance
If the solid content of the slurry is increased to improve energy density, then the energy density increases, but the viscosity becomes too high for suitable electrode preparation process
Solution Approach 1:
The invention extracts and eliminates the solvent from the system, thereby removing the viscosity constraint that limits solid content in conventional slurry processes. Without solvent, the dry mixture can achieve very high solid content (essentially 100% solid materials) while remaining processable through dry mixing and coating techniques.
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
This approach improves energy density, productivity, and process safety by eliminating the need for solvents, reducing porosity, and enhancing the uniformity and adhesion of the positive electrode active material layer.
Implementation Method 1
forming a solid electrolyte by mixing a lithium salt and a polymer for a solid electrolyte in a dry atmosphere
Implementation Method 2
forming a dry mixture by stirring after adding a conductive agent and a positive electrode active material to the solid electrolyte in a dry atmosphere
Implementation Method 3
applying a shear force of 20 N to 150 N to the dry mixture
Implementation Method 4
pressing after coating a current collector with the dry mixture
Data Source
AI summary
The present invention relates to a method of preparing a positive electrode which includes forming a solid electrolyte by mixing a lithium salt and a polymer for a solid electrolyte in a dry atmosphere, forming a dry mixture by stirring after adding a conductive agent and a positive electrode active material to the solid electrolyte in a dry atmosphere, and pressing after coating a current collector with the dry mixture.