Cobalt Hydroxide Synthesis via Ammonium Citrate Dispersant
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Solution Overview
Problem
Cobalt hydroxide synthesized by chemical methods tends to form colloids or flocci, is difficult to filter, prone to agglomeration during drying, and easily oxidizes, leading to reduced yield and performance issues in lithium cobalt oxide batteries.
Innovation Solution
A synthesis method involving stirring and heating ammonium citrate with a cobalt salt and mixed alkali liquor under a protective atmosphere, followed by alkali-leaching and detergent washing to produce cobalt hydroxide with high purity, regular particles, uniform size distribution, and large specific surface area, preventing agglomeration and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt hydroxide is synthesized by chemical method, then cobalt hydroxide is produced, but it forms colloids or flocci and has low surface activity
Solution Approach 1:
The patent introduces ammonium citrate as an intermediary substance during the synthesis process. This mediator prevents direct agglomeration of cobalt hydroxide particles by forming stable complexes, thereby maintaining high surface activity while enabling efficient production of cobalt hydroxide.
2Ease of manufacture
If cobalt hydroxide slurry is filtered, then filtration is achieved, but small-grained slurry is difficult to filter and requires a lot of water
Solution Approach 1:
The patent changes the physical and chemical parameters of the cobalt hydroxide particles through controlled synthesis conditions and the use of ammonium citrate. This results in particles with optimized size distribution and surface properties that facilitate easier filtration with reduced water requirements.
3Loss of time
If cobalt hydroxide is dried, then drying is achieved, but product is prone to agglomeration and is not easily dried
Solution Approach 1:
The patent applies preliminary action by introducing protective measures during the synthesis stage. The ammonium citrate forms a protective layer around the cobalt hydroxide particles before drying occurs, preventing agglomeration during the subsequent drying process and enabling faster, more efficient drying.
4Productivity
If cobalt hydroxide is processed, then processing is achieved, but it is easily oxidized into cobalt oxyhydroxide, resulting in reduced yield
Solution Approach 1:
The patent creates an inert protective atmosphere during the synthesis and processing of cobalt hydroxide using ammonium citrate. This inert environment prevents oxidation of cobalt hydroxide into cobalt oxyhydroxide, thereby maintaining high yield while enabling efficient 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 results in cobalt hydroxide with improved surface activity, reduced sulfur content, and enhanced processability, leading to increased battery capacity and stability by preventing agglomeration and oxidation during the drying process.
Implementation Method 1
the ammonium citrate solution can serve as a dispersant for the entire reaction process to prevent the agglomeration of particles during the reaction process
Implementation Method 2
The alkali-leaching and detergent-washing can reduce an S content in cobalt hydroxide
Implementation Method 3
washing a resulting slurry with a detergent
Implementation Method 4
cobalt hydroxide has high reaction activity and is easily oxidized into cobalt oxyhydroxide
Data Source
AI summary
The present disclosure belongs to the technical field of metal oxide materials, and discloses a synthesis method of cobalt hydroxide and cobalt hydroxide. The synthesis method includes: (1) stirring and heating ammonium citrate, introducing a protective gas, adding a cobalt salt and a mixed alkali liquor to allow a reaction, and adjusting a pH to obtain a cobalt hydroxide slurry; and (2) subjecting the cobalt hydroxide slurry to alkali-leaching, filtering, and slurrying a resulting filter residue; and washing a resulting slurry with a detergent, and drying the resulting slurry to obtain the cobalt hydroxide. In the present disclosure, ammonium citrate is used as a base solution, and a cobalt solution and a mixed alkali liquor are added to synthesize a cobalt hydroxide slurry in one step under a protective atmosphere.