Positive Electrode Material Formation for Particle and Impurity Control
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Solution Overview
Problem
The existing methods for forming lithium cobalt oxide in lithium-ion secondary batteries face challenges in controlling the shape, particle diameter, and impurity management of the positive electrode active material, leading to difficulties in achieving high discharge capacity, withstanding high charge and discharge voltages, and maintaining battery longevity.
Innovation Solution
A method involving a reaction between a cobalt aqueous solution and an alkaline aqueous solution to form a cobalt compound, followed by heat treatments with specific temperature ranges to create composite oxides, incorporating additive elements like magnesium and fluorine, and using chelate agents to control particle growth and impurity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a method for forming lithium cobalt oxide is employed as described in Patent Document 1, then high discharge capacity can be achieved, but management of the positive electrode active material becomes difficult and control over shape, particle diameter, and impurity levels is lost
Solution Approach 1:
The patent applies preliminary action by preparing cobalt compound particles with controlled shape and size before the main synthesis reaction. The cobalt compound is formed first with specific morphology (spheroidal or irregular shape, 1-10 μm diameter), then used as a precursor in the lithium cobalt oxide formation reaction. This preliminary preparation enables subsequent precise control over the final product's properties while maintaining high discharge capacity.
2Ease of manufacture
If pre-synthesized lithium cobalt oxide is purchased and used, then manufacturing process is simplified, but impurity management and material quality control become difficult
Solution Approach 1:
The patent uses a cobalt compound as an intermediary substance in the synthesis process. Instead of directly purchasing final lithium cobalt oxide, the method employs cobalt compound particles as a intermediate precursor that can be precisely controlled in terms of purity and properties. This intermediary step allows for better quality control while maintaining manufacturing efficiency, as the cobalt compound serves as a reliable starting material for the subsequent reaction.
3Productivity
If conventional methods are used to form positive electrode active material, then production speed may be maintained, but the material cannot withstand high charge and discharge voltages and deteriorates quickly
Solution Approach 1:
The patent applies local quality by creating a specific surface structure on the lithium cobalt oxide particles. The method produces material with controlled surface characteristics (spheroidal or irregular shape with specific surface area) that enhances voltage resilience. This local structural optimization at the particle level improves overall battery performance and longevity while maintaining production efficiency through the streamlined two-step process.
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 method allows for the precise management of the positive electrode active material, enhancing its discharge capacity, voltage resilience, and reducing deterioration, resulting in a more efficient and long-lasting battery performance.
Implementation Method 1
causing a reaction between a cobalt aqueous solution and an alkaline aqueous solution to form a cobalt compound
Implementation Method 2
mixing the first composite oxide and a compound containing a first additive element and performing a second heat treatment to form a second composite oxide
Data Source
AI summary
A novel method for forming a positive electrode active material is provided. The method for forming a positive electrode active material includes causing a reaction between a cobalt aqueous solution and an alkaline aqueous solution to form a cobalt compound; mixing the cobalt compound and a lithium compound and performing a first heat treatment to form a first composite oxide; mixing the first composite oxide and a compound containing a first additive element and performing a second heat treatment to form a second composite oxide; and mixing the second composite oxide and a compound containing a second additive element and performing a third heat treatment. The first heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1100° C. The second heat treatment is performed at a temperature higher than or equal to 700° C. and lower than or equal to 1000° C. The third heat treatment is performed at a temperature equal to the temperature of the second heat treatment or at a temperature lower than the temperature of the second heat treatment.