Cathode Active Material Coating for Durable Dry Battery Electrodes
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Solution Overview
Problem
The manufacturing of lithium secondary batteries faces challenges in achieving uniform drying of electrode active layers, leading to defects like pinholes and cracks, and the use of solvents poses health risks and high processing costs, while dry electrodes struggle with PTFE binder fiberization and electrode durability.
Innovation Solution
A positive electrode active material comprising lithium transition metal oxide particles coated with an amorphous carbon-based layer and a carbon nanotube layer, which improves surface unevenness and conductive paths, facilitating PTFE fiberization and reducing battery resistance, manufactured using a mechanofusion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a drying process is used to remove solvent from electrode mixture, then solvent is removed and electrode is formed, but defects like pinholes and cracks occur and uniform drying is difficult to achieve
Solution Approach 1:
The invention extracts and removes the solvent from the electrode mixture through a drying process, separating the liquid component from the solid electrode materials. This extraction approach allows solvent removal while maintaining electrode structure integrity.
Solution Approach 2:
The invention applies preliminary actions by optimizing the drying process parameters before defects occur. The controlled drying approach prevents pinholes and cracks by managing solvent evaporation rates and temperature profiles in advance.
2Ease of manufacture
If solvent is used in electrode mixture, then particles are dispersed and coating is facilitated, but health risks arise and processing costs increase
Solution Approach 1:
The invention converts the harmful solvent into a beneficial dispersing medium by using it only during the mixing and coating stages, then completely removing it through drying. The solvent serves its useful purpose of particle dispersion without leaving harmful residues in the final product.
Solution Approach 2:
The invention discards the solvent after it has fulfilled its function of particle dispersion and coating facilitation. The drying process eliminates the solvent from the electrode structure, removing health risks while maintaining the manufacturing benefits.
3Strength
If PTFE binder is used in dry electrode, then electrode shape is maintained and materials are bound, but fiberization is difficult to activate and durability is reduced
Solution Approach 1:
The invention changes the physical and chemical parameters of the PTFE binder system, including molecular weight, crystallinity, and processing temperature, to optimize both fiberization activation and electrode durability. These parameter adjustments enable simultaneous achievement of shape maintenance and long-term reliability.
Solution Approach 2:
The invention uses composite material approaches by combining PTFE binder with other binding agents or modifying the PTFE structure through additives and processing methods. This creates a composite binder system that overcomes the limitations of pure PTFE while maintaining shape maintenance capabilities.
4Volume of moving object
If thick film electrode is manufactured using conventional drying, then electrode thickness is achieved, but non-uniform drying occurs and quality deteriorates
Solution Approach 1:
The invention segments the drying process into multiple stages with different temperature and humidity conditions. This segmented approach allows thick film electrodes to dry uniformly by controlling solvent evaporation at different depths and rates throughout the electrode thickness.
Solution Approach 2:
The invention applies periodic action through cyclic drying processes with alternating heating and cooling phases. This periodic treatment ensures uniform moisture removal from thick electrodes while preventing surface defects and maintaining internal structure integrity.
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 solution enhances electrode productivity, durability, and battery performance by activating PTFE fiberization, improving conductive paths, and reducing resistance, thereby extending battery lifespan and output characteristics.
Implementation Method 1
an amorphous carbon-based coating layer which is formed in the form of a coating film on the surface of the lithium transition metal oxide particles; and a carbon nanotube coating layer which is formed on the amorphous carbon-based coating layer
Implementation Method 2
manufactured using a mechanofusion process
Implementation Method 3
when a shearing force is applied under specific conditions, they are pulled out long into fibers, and these fibers play a role of connecting the active material and the active material, and the active material and the conductive material to maintain the electrode shape
Data Source
AI summary
A positive electrode active material for secondary battery includes lithium transition metal oxide particles; an amorphous carbon-based coating layer formed in the form of a coating film on the surface of the lithium transition metal oxide particles; and a carbon nanotube coating layer formed on the amorphous carbon-based coating layer. A method for manufacturing the same and a freestanding film including the same are also provided. Further, a dry positive electrode; and a secondary battery including the dry positive electrode are also provided.