Lithium Compound Magnetic Separation for Battery Purity
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Solution Overview
Problem
Current methods for producing positive active materials for nonaqueous electrolyte secondary batteries are inefficient in reducing the amount of magnetically attractable substances, leading to prolonged processing times and increased production costs due to the need for extensive magnetic separation and drying steps.
Innovation Solution
A lithium compound with reduced magnetically attractable substances is used, obtained by mixing it with a transition metal composite hydroxide or oxide, and subjected to magnetic separation with a magnetized screen, reducing the amount of magnetically attractable substances to 0.0007 mass % or less, thereby shortening the production time and preventing micro-shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extensive magnetic separation and drying steps are performed to reduce magnetically attractable substances, then the amount of magnetically attractable substances is reduced, but the processing time and production cost increase
Solution Approach 1:
The patent applies preliminary action by controlling the amount of magnetically attractable substances in the lithium compound before mixing with the metal compound. This preventive measure reduces the need for extensive subsequent magnetic separation steps, thereby shortening processing time while maintaining the required level of purity in the positive active material
Solution Approach 2:
The patent extracts and removes magnetically attractable substances from the lithium compound through magnetic separation before the mixing step. This early extraction prevents these substances from being incorporated into the final positive active material, reducing the need for prolonged processing later
2Manufacturing precision
If extensive magnetic separation and drying steps are performed to reduce magnetically attractable substances, then the amount of magnetically attractable substances is reduced, but the production cost increases
Solution Approach 1:
The patent applies preliminary action by controlling the amount of magnetically attractable substances in the lithium compound before mixing with the metal compound. This preventive measure reduces the need for extensive subsequent magnetic separation steps, thereby shortening processing time while maintaining the required level of purity in the positive active material
Solution Approach 2:
The patent extracts and removes magnetically attractable substances from the lithium compound through magnetic separation before the mixing step. This early extraction prevents these substances from being incorporated into the final positive active material, reducing the need for prolonged processing later
3Productivity
If metal powder is present in the positive active material, then the production process is simpler, but micro-shorting occurs and battery capacity is lowered
Solution Approach 1:
The patent extracts and removes magnetically attractable metal powders from the lithium compound before mixing with the metal compound. This extraction prevents metal powder contamination in the final positive active material, eliminating micro-shorting risks while maintaining production efficiency
Solution Approach 2:
The patent applies preliminary action by controlling the amount of magnetically attractable substances in the lithium compound before mixing with the metal compound. This preventive measure reduces the need for extensive subsequent magnetic separation steps, thereby shortening processing time while maintaining the required level of purity in the positive active material
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
The method effectively reduces the amount of magnetically attractable substances in the positive active material to 0.02 mass ppm or less, preventing micro-shorting and under voltage failures while significantly reducing production time and costs.
Implementation Method 1
when water, and a magnet having a magnetic flux density of 0.9 tesla are added to and mixed with the lithium compound, and then the mixture is stirred for 30 minutes, the amount of magnetically attractable substances to be captured by the magnet is 0.0007 mass % or less
Data Source
AI summary
A lithium compound with which a positive active material containing a decreased amount of magnetically attractable substances can be easily obtained while shortening the total time for production of a positive electrode for a nonaqueous electrolyte secondary battery. The lithium compound is used for producing a positive active material for a nonaqueous electrolyte secondary battery, with which a lithium transition metal composite oxide can be obtained by mixing the lithium compound with a transition metal composite hydroxide or the like obtained by crystallization reaction. A positive active material in which the amount of magnetically attractable substances contained is 0.02 mass ppm or less can be easily obtained while shortening the total time for production of the positive active material.