Battery-Grade Cobalt Tetroxide with High Tap Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing cobalt tetroxide result in low tap density, particle bursting, and uneven distribution of Li, affecting battery performance due to loose core-shell structures and high calcination temperatures.
Innovation Solution
A method involving controlled coprecipitation and calcination of cobalt oxyhydroxide, adjusting pH and flow rates to achieve a 2-4 μm particle size, followed by low and high temperature zones for sintering, to produce a compact cobalt tetroxide with high tap density and specific surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt carbonate is sintered to release CO2, then cobalt tetroxide is obtained, but particle bursting occurs due to rapid gas release
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor from cobalt carbonate (49.6% Co content) to cobalt oxyhydroxide (higher Co content), which fundamentally alters the decomposition behavior during sintering. This parameter change eliminates rapid CO2 release and associated particle bursting, achieving consistent 2-4 μm particle sizes.
Solution Approach 2:
The patent converts the harmful rapid CO2 release from cobalt carbonate decomposition into a beneficial controlled water molecule release from cobalt oxyhydroxide decomposition. Water molecules are flexible and do not cause particle bursting, thus converting a harmful gas release mechanism into a beneficial one that maintains particle integrity.
2Manufacturing precision
If sintering temperature is strictly controlled, then particle bursting is reduced, but production efficiency decreases
Solution Approach 1:
The patent changes the precursor material parameters from cobalt carbonate to cobalt oxyhydroxide, which has different thermal decomposition characteristics. This allows sintering at higher temperatures (900-1100°C) without particle bursting, thus improving both productivity and particle size consistency simultaneously.
3Shape
If core-shell structure precursor is used, then particle morphology is formed, but Li distribution becomes uneven requiring higher calcination temperature
Solution Approach 1:
The patent performs preliminary homogeneous mixing of Li source with cobalt oxyhydroxide before calcination, ensuring uniform Li distribution throughout the particle structure. This preliminary action eliminates the need for higher calcination temperatures to achieve uniform distribution, maintaining both morphology and reducing energy consumption.
4Quantity of substance
If cobalt carbonate with low Co content is used, then CO2 release occurs during sintering, but tap density remains low
Solution Approach 1:
The patent changes the precursor from cobalt carbonate (49.6% Co) to cobalt oxyhydroxide (higher Co content), increasing the effective cobalt content. This parameter change reduces the total material volume needed and eliminates excessive gas release, thereby improving tap density and reducing energy consumption associated with handling and processing.
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 cobalt tetroxide with improved tap density and stability, reducing particle bursting and environmental impact while lowering energy consumption.
Implementation Method 1
adding a cobalt salt solution and an alkaline solution by parallel flows at certain feed rates respectively to a reactor with a base solution and an air flow, controlling pH value of a system at 10-11 by adjusting flow rate of the alkaline solution for coprecipitation reaction
Implementation Method 2
adding a cobalt salt solution and an alkaline solution by parallel flows at certain feed rates respectively to a reactor with a base solution and an air flow
Implementation Method 3
calcining the dried cobalt oxyhydroxide obtained in step 2 through a low temperature zone and a high temperature zone in sequence
Implementation Method 4
calcining the dried cobalt oxyhydroxide obtained in step 2 through a low temperature zone and a high temperature zone in sequence, thus obtaining 2-4 μm battery-grade cobalt tetroxide
Data Source
AI summary
The present invention discloses a preparation method for 2-4 μm battery-grade cobalt tetroxide, comprises following steps: 1) adding a cobalt salt solution and an alkaline solution by parallel flows to a reactor with a base solution and an air flow, controlling pH value of a system by adjusting flow rate of the alkaline solution for coprecipitation reaction at a certain stirring rate, decreasing the pH value of the reaction system and increasing flow rate of the cobalt salt solution after the reaction solutions begin to overflow; 2) aging and drying the cobalt oxyhydroxide slurry in sequence; 3) calcining the dried cobalt oxyhydroxide. By adopting this method, tap density of the battery-grade cobalt tetroxide obtained is much higher than that of cobalt tetroxide with a same particle size specification prepared by the prior art.