Dry Positive Electrode Coating for Low-Porosity Solid Electrolytes
Find Innovative SolutionsGenerate Solutions
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 reduce energy density and increase porosity, making it difficult to achieve uniform active material layers and high solid content in the electrodes.
Innovation Solution
A method involving the formation of a solid electrolyte by mixing a lithium salt and polymer in a dry atmosphere, followed by adding a conductive agent and positive electrode active material to create a dry mixture, which is then coated and pressed onto a current collector without using a solvent, thereby improving productivity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a solvent is used to mix solid electrolyte with electrode slurry, then the solid electrolyte can be uniformly distributed, 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 preparation process. By using a dry mixing process without solvent, the patent achieves uniform distribution of solid electrolyte while maintaining high solid content and reducing porosity in the final electrode product.
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 enables the solid electrolyte to be uniformly distributed through dry mixing, thereby increasing solid content and reducing porosity while maintaining compositional uniformity.
2Productivity
If drying temperature is increased to improve productivity, then drying speed increases, but crystallization of solid electrolyte occurs and voids are formed
Solution Approach 1:
The invention extracts and eliminates the drying step entirely by using a dry mixing process from the beginning. Since no solvent is used, there is no drying required, thus avoiding crystallization and void formation while maintaining productivity through the elimination of the drying process.
Solution Approach 2:
The invention performs the mixing of solid electrolyte with electrode materials in advance in a dry state, before any potential drying step. This preliminary dry mixing ensures uniform distribution without requiring subsequent high-temperature drying that would cause crystallization and void formation.
3Ease of manufacture
If solvent is used to prepare electrode slurry, then mixing is easier, but thickness of active material layer is reduced and uniform thickness is difficult to achieve
Solution Approach 1:
The invention extracts and eliminates the solvent from the mixing process. By using dry mixing, it maintains ease of manufacture through simple mechanical mixing while achieving uniform thickness of the active material layer, as confirmed by experimental data showing thickness variation of less than 5 micrometers.
4Quantity of substance
If solid content of slurry is increased to improve energy density, then viscosity becomes too high for suitable electrode preparation, but productivity is reduced
Solution Approach 1:
The invention extracts and eliminates the solvent from the slurry preparation process. By using a dry mixing process, it achieves high solid content (100% solid content since no solvent is present) while maintaining suitable processing characteristics and high productivity, as the dry mixture can be directly coated and pressed without viscosity limitations.
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 enhances energy density and productivity by eliminating the need for a solvent, reducing porosity, and improving process safety, while allowing for uniform thickness and loading 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
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.