Lithium Nickel Composite Oxide Cathode Material Manufacturing
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Solution Overview
Problem
Lithium nickel composite oxide cathode active materials for non-aqueous electrolyte secondary batteries face issues with thermal stability, cycling characteristics, and impurity-related problems, such as lithium carbonate decomposition and proton exchange leading to reduced electrical conductivity and particle strength, which affect battery performance and durability.
Innovation Solution
A manufacturing method involving the formation of a slurry with lithium nickel composite oxide, followed by washing and heat treatment in an oxygen atmosphere at specific temperatures to form a layered hexagonal structure with a coating layer, ensuring lithium supplementation and improved particle strength and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If heat treatment is performed in an air atmosphere to remove moisture, then moisture content is reduced, but lithium reacts with carbon in the air to form lithium carbonate, worsening the impurity problem
Solution Approach 1:
The patent applies inert atmosphere by conducting heat treatment in a nitrogen atmosphere instead of air atmosphere. This prevents lithium from reacting with carbon in the air to form lithium carbonate, while still effectively removing moisture from the cathode active material. The nitrogen atmosphere serves as an inert environment that allows moisture removal without causing harmful chemical reactions.
2Object-generated harmful factors
If heat treatment is performed in a non-carbon or vacuum atmosphere to prevent lithium carbonate formation, then impurity generation is suppressed, but lithium undergoes proton exchange with hydrogen ions in washing solution, worsening electrical conductivity
Solution Approach 1:
The patent uses nitrogen atmosphere as an inert environment that achieves both objectives: preventing lithium carbonate formation by excluding carbon-containing air, and preventing proton exchange by providing a barrier between the material and hydrogen ions in the washing solution. The nitrogen atmosphere thus protects the material while maintaining electrical conductivity.
3Loss of substance
If washing with water is performed to remove lithium salt impurities, then impurity removal is improved, but particle strength decreases causing cracks during electrode formation, worsening manufacturing quality
Solution Approach 1:
The patent applies parameter changes by controlling the pH value of the washing solution to be 5.0 or less. This specific parameter change optimizes the washing process to effectively remove lithium salt impurities while minimizing damage to particle strength. The controlled low pH environment enables selective impurity removal without excessive weakening of the cathode active material particles.
4Loss of substance
If washing with water is performed to remove impurities, then purity is improved, but cracks occur during rolling pressure application, worsening electrode density
Solution Approach 1:
The patent uses parameter changes by controlling the pH value to 5.0 or less during washing. This parameter optimization removes impurities effectively while preserving particle integrity, preventing cracks during subsequent rolling pressure application in electrode formation. The controlled pH ensures both purity improvement and manufacturing precision are maintained.
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 produces a cathode active material with enhanced charging and discharging capacity, output characteristics, and weather resistance, while maintaining low cathode resistance and allowing for industrial-scale production.
Implementation Method 1
perform heat treatment in an oxygen atmosphere at a temperature of no less than 120° C. and no greater than 550° C. By performing heat treatment under such conditions, it is possible to remove water through condensation and evaporation
Implementation Method 2
when heat treatment is performed in an air atmosphere, the lithium that exists on the surface of the lithium nickel composite oxide reacts with carbon in the air and becomes lithium carbonate
Data Source
AI summary
The purpose of the present invention is to easily provide at low cost, a cathode active material for non-aqueous electrolyte secondary batteries, which exhibits high particle strength and high weather resistance, while enabling achievement of excellent charge and discharge capacity and excellent output characteristics in cases where the cathode active material is used as a cathode material of a non-aqueous electrolyte secondary battery. A slurry of from 500 g/L to 2000 g/L is formed by adding water to a powder of a lithium nickel composite oxide represented by the general formula (A): LizNi1-x-yCoxMyO2, where 0.10≤x≤0.20, 0≤y≤0.10, 0.97≤z≤1.20, and M represents at least one element selected from among Mn, V, Mg, Mo, Nb, Ti and Al); the slurry is washed with water by stirring; and after filtration, the resulting material is subjected to a heat treatment at a temperature of from 120° C. to 550° C. (inclusive) in an oxygen atmosphere having an oxygen concentration of 80% by volume or more.