Dry Positive Electrode Coating for Loading and Porosity Control
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Solution Overview
Problem
The existing methods for manufacturing lithium-sulfur secondary battery positive electrodes face challenges such as reduced energy density due to the use of binders and conductive materials, high costs, and complexity in the dry process, particularly in adjusting loading and porosity, and potential damage to materials during fiberization.
Innovation Solution
An apparatus and method that utilize a dry process without a binder, featuring a feeding part for powder and a shaping part with pre-shaping, roll-pressing, and bonding rolls to form a positive electrode layer on a current collector, allowing independent adjustment of loading and porosity, and incorporating a recovery unit for reusing remaining powder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a wet process is used to manufacture the positive electrode, then the coating process is simple and can be easily implemented, but the loading amount of the positive electrode active material is reduced due to the electrically conductive material and binder used in preparing the slurry, resulting in reduced energy density
Solution Approach 1:
The invention extracts and eliminates the binder from the electrode manufacturing process. By using a dry process without binder, the patent removes the harmful component that reduces active material loading, thereby increasing energy density while maintaining manufacturing feasibility through alternative processing methods
Solution Approach 2:
The invention changes the physical state parameter from wet (slurry-based) to dry (powder-based) processing. This parameter change eliminates the need for binder and solvent, allowing higher loading amounts of active material while simplifying the manufacturing process by removing drying steps
2Ease of manufacture
If a wet process is used to manufacture the positive electrode, then the coating process is straightforward, but additional costs are incurred due to mixing, coating, and drying processes, and remaining moisture in the positive electrode causes problems
Solution Approach 1:
The invention extracts and eliminates the drying process from the manufacturing sequence by using a dry process approach. This removes the source of moisture problems and reduces overall process complexity while maintaining ease of manufacture through simplified material application
Solution Approach 2:
The invention implements a continuous dry coating process that eliminates the intermittent drying steps required in wet processes. This continuous action approach reduces process complexity and eliminates moisture-related issues while maintaining manufacturing efficiency
3Quantity of substance
If a dry process is used to manufacture the positive electrode, then the binder-free approach can maintain high energy density, but the fiberization of the binder is essential which limits the type and content of usable binder and complicates the process
Solution Approach 1:
The invention extracts and eliminates the binder entirely from the system. By removing the binder component completely rather than attempting to fiberize it, the patent simplifies the process by eliminating pre-mixing and milling operations while maintaining high energy density through direct powder coating
Solution Approach 2:
The invention segments the manufacturing process into independent steps: powder preparation, direct coating, and sintering. This segmentation eliminates the need for binder fiberization and complex pre-mixing, allowing flexible selection of materials while maintaining process simplicity and high energy density
4Quantity of substance
If a dry process is used to manufacture the positive electrode, then binder-free manufacturing can increase energy density, but the high shear force applied during fiberization of the binder may crush the positive electrode active material and electrically conductive material
Solution Approach 1:
The invention extracts and eliminates the binder fiberization step that causes material damage. By removing the binder entirely and using a direct powder coating approach, the patent prevents crushing of the active material and conductive material while maintaining high energy density
Solution Approach 2:
The invention performs preliminary preparation of the powder mixture before coating, ensuring proper distribution of active material and conductive material without requiring high-shear fiberization. This preliminary action protects material integrity while achieving the desired composition for high energy density
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 enables efficient production of lithium secondary battery positive electrodes with controlled loading and porosity, reducing costs and complexity, and preventing material damage, while maintaining high energy density without the need for binders.
Implementation Method 1
a sintering unit for sintering the positive electrode material layer formed on one surface of the positive electrode current collector
Implementation Method 2
a press unit for pressing the positive electrode material layer formed on one surface of the positive electrode current collector, wherein the press unit comprises: a press roll that rotates about a press roll axis
Data Source
AI summary
An apparatus and method for manufacturing a positive electrode for a lithium secondary battery are provided. The apparatus and the method are effective in controlling a loading amount and a porosity of a positive electrode by manufacturing the same by a dry process comprising a step of feeding a positive electrode material in the form of a powder on a positive electrode current collector and a step of pre-shaping, roll-pressing, and bonding.