Cobalt Hydroxide Particles Narrow Particle Size Distribution
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Solution Overview
Problem
Current cobalt hydroxide particles used as precursors for lithium-cobalt composite oxides in non-aqueous electrolyte secondary batteries lack sufficient filling property and uniformity, leading to suboptimal performance in terms of energy density and cycle characteristics.
Innovation Solution
Cobalt hydroxide particles with a narrow particle size distribution and high sphericity are produced through a controlled nucleation and particle growth process using a chlorine-containing cobalt aqueous solution, followed by calcination with a lithium compound to achieve high filling property and coulomb efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cobalt hydroxide particles are produced using conventional continuous processes with controlled pH and temperature, then productivity is improved, but particle size distribution becomes wide and filling property deteriorates
Solution Approach 1:
The continuous crystallization process is segmented into distinct stages: nucleation stage with rapid pH increase to form nuclei, and growth stage with controlled pH to allow uniform particle growth. This segmentation enables both high productivity and narrow particle size distribution by controlling when nucleation occurs versus when growth occurs.
Solution Approach 2:
Ammonium ions are added preliminarily to the reaction system before cobalt salt addition. These ammonium ions act as buffering agents that control pH during the subsequent cobalt hydroxide formation, ensuring uniform nucleation and growth conditions that produce narrow particle size distribution while maintaining continuous production capability.
2Volume of moving object
If particle diameter is enlarged to improve filling property, then energy density increases, but particle sphericity and density uniformity deteriorate
Solution Approach 1:
The crystallization conditions are specifically controlled to promote spherical particle morphology. By maintaining appropriate pH ranges during growth and using ammonium ion buffering, the particles develop rounded, spherical shapes rather than irregular or crystalline forms, maximizing packing efficiency and filling property.
Solution Approach 2:
The pH parameter is dynamically changed and controlled at different stages: rapidly increased during nucleation, then carefully maintained within specific ranges during growth. This parameter control ensures particles achieve optimal size while maintaining spherical shape and uniform density, resolving the contradiction between size enlargement and shape preservation.
3Productivity
If pH value is controlled in the range of 11.0 to 13.5 during continuous crystallization, then production efficiency is improved, but particle denseness and sphericity deteriorate
Solution Approach 1:
The pH control follows a periodic pattern: rapid pH increase during nucleation phase for high productivity, followed by pH maintenance in the 9.5-10.5 range during growth phase for optimal particle quality. This periodic action allows the system to achieve both high production efficiency and excellent particle denseness by applying different pH conditions at different time periods.
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 resulting cobalt hydroxide particles and lithium cobalt composite oxide active materials exhibit enhanced filling density, increased battery capacity, and improved coulomb efficiency, leading to more efficient energy storage and prolonged battery life.
Implementation Method 1
a cobalt hydroxide particle production process comprising: a nucleation step for performing nucleation by controlling a pH value and a particle growth step for growing particles
Implementation Method 2
followed by calcination with a lithium compound to achieve high filling property and coulomb efficiency
Data Source
AI summary
Obtaining cobalt hydroxide particles having a high filling property and a high density. The cobalt hydroxide particles used as a precursor for a positive electrode active material of a non-aqueous electrolyte secondary battery, including spherical secondary particles of flocculated primary particles, wherein average aspect ratio of the secondary particles is 0.7 or more, average particle diameter is 5 to 35 μm, and a value of (d90−d10)/MV indicating a dispersion of a particle size distribution is 0.6 or less, wherein, in sectional observation of the secondary particles, a ratio (N/L) of number (N) of gaps with maximum long diameter 0.3 μm or more recognized in particles of the secondary particles with sectional long diameter 3 μm or more to sectional long diameter (L) of the secondary particles is 1.0 or less, and also, maximum long diameter of the gaps is 15% or less of sectional long diameter of the secondary particles.