Positive Electrode Dry Mixing for High-Density Solid-State Batteries
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Solution Overview
Problem
Existing methods for preparing positive electrodes in secondary batteries face challenges such as reduced solid content in electrode slurries, increased porosity due to solvent use, and limitations in achieving high energy density and mechanical stability.
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 the addition of a conductive agent and positive electrode active material to create a dry mixture, which is then coated onto a current collector and pressed to form the positive electrode.
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
Solution Approach 1:
The patent removes the solvent from the electrode slurry system entirely, extracting the harmful element that caused reduced solid content. By using a dry mixing process instead of a wet process, the solid electrolyte is directly mixed with other solid components without any liquid medium, thereby maintaining high solid content while achieving uniform distribution through mechanical mixing alone.
2Productivity
If drying temperature is increased to improve productivity, then drying speed increases, but crystallization of solid electrolyte occurs and unintended voids are formed
Solution Approach 1:
The patent eliminates the drying step entirely by removing the solvent from the system. Since no solvent is present, there is no drying process required, and consequently no risk of crystallization or void formation associated with high-temperature drying. The electrode slurry is applied in a wet state and the solvent evaporates naturally during subsequent battery assembly processes at lower temperatures.
Solution Approach 2:
The patent performs the mixing and preparation of the electrode slurry in advance with the understanding that no aggressive drying will be needed. The solid electrolyte is pre-mixed with other components in a controlled manner that prevents crystallization, and the slurry is applied to the current collector before any thermal processing occurs, thereby preventing void formation from the outset.
3Quantity of substance
If solid content of slurry is increased to improve energy density, then more active material can be packed, but viscosity becomes too high for suitable electrode preparation
Solution Approach 1:
The patent changes the physical state parameter of the mixing system from liquid-based (wet process) to dry-based (dry process). By eliminating the liquid solvent, the system can accommodate much higher solid content without the viscosity constraints that plague slurry-based processes. The dry powder mixture maintains flowability and processability through mechanical mixing rather than relying on liquid lubrication.
4Quantity of substance
If porosity of active material layer is reduced to increase energy density, then more material can be packed, but mechanical stability may be compromised
Solution Approach 1:
The patent uses a composite material approach by combining the solid electrolyte with other functional components (conductive agents, binders, active materials) in a dry mixture. This composite structure provides both the low porosity needed for high energy density and the mechanical stability needed for structural integrity, as each component contributes different properties that complement each other in the final electrode structure.
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, improves mechanical stability, and increases productivity by eliminating the need for solvents, reducing porosity, and simplifying the preparation process.
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.