Cathode Precursor Seed Recycling for Uniform Particle Size
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Solution Overview
Problem
Existing methods for preparing positive electrode active material precursors face challenges in achieving uniform particle size distribution and reproducibility, particularly due to deviations in residence time and reaction time in continuous stirring tank reactors, and simultaneous seed formation and growth in batch reactors, leading to non-uniform particle sizes and quality dispersion.
Innovation Solution
A method involving a reactor connected to a continuous grinder is used to form and reintroduce positive electrode active material precursor seeds, allowing simultaneous formation and grinding to achieve uniform particle size distribution, with specific conditions for pH, temperature, and discharge rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuous stirring tank reactor is used to prepare positive electrode active material precursor, then productivity is improved by continuous introduction of raw materials and simultaneous discharge of precursor, but particle size distribution becomes non-uniform due to deviation in residence time and reaction time
Solution Approach 1:
The patent divides the particle formation process into two distinct stages: (1) seed formation stage where small uniform seeds are formed first, and (2) particle growth stage where seeds grow into final particles. This segmentation allows each stage to be optimized independently, with the seed formation stage controlling nucleation for uniform size distribution and the growth stage controlling final particle size, thereby resolving the contradiction between productivity and particle size uniformity.
Solution Approach 2:
The patent performs preliminary seed formation before particle growth by controlling the reaction conditions to form small uniform seeds first. These pre-formed seeds serve as nuclei for subsequent particle growth, ensuring that all particles start from a uniform size basis. This preliminary action of seed formation resolves the particle size distribution issue while maintaining continuous production capability.
2Manufacturing precision
If a batch reactor is used to prepare positive electrode active material precursor, then particle size distribution becomes uniform by controlling reaction conditions, but quality reproducibility deteriorates due to simultaneous seed formation and growth making it difficult to reproduce the same particle characteristics
Solution Approach 1:
The patent segments the batch reactor process into distinct seed formation and growth stages with different controlled conditions. By separating these stages temporally and controlling each independently, the process becomes more reproducible. The seed formation stage establishes uniform nuclei, and the subsequent growth stage develops them into final particles, making the overall process more controllable and reproducible across batches.
Solution Approach 2:
The patent implements a continuous process where seed formation and particle growth occur in sequence without interruption. The continuous introduction of raw materials and continuous discharge of precursor maintain steady-state conditions throughout the process, eliminating the start-stop nature of batch operations. This continuity ensures consistent reaction conditions and improves quality reproducibility while maintaining uniform particle size distribution.
3Productivity
If the reactor size is increased for mass-production through batch reactor, then productivity is improved, but quality dispersion increases because the stirrer rotation becomes faster and incomplete facilities cause seed quality dispersion
Solution Approach 1:
The patent separates seed formation and particle growth into distinct stages, allowing each to be optimized for its specific function. The seed formation stage focuses on creating uniform nuclei under controlled conditions, while the growth stage handles the bulk material development. This segmentation allows the use of appropriately sized reactors for each stage, avoiding the quality dispersion issues that arise from using oversized reactors for seed formation.
Solution Approach 2:
The patent performs preliminary seed formation in a controlled manner before scaling up to larger reactors for particle growth. By establishing uniform seeds first in controlled conditions and then using these seeds as starting material for larger-scale production, the process maintains seed quality uniformity even when producing large quantities. This preliminary action of seed formation protects against quality dispersion in mass-production.
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 a positive electrode active material precursor with narrow and uniform particle size distribution, enhancing production efficiency and quality reproducibility, and improves the sphericity and uniformity of the particles.
Implementation Method 1
introducing the positive electrode active material precursor seed discharged from the reactor into the continuous grinder
Implementation Method 2
raw materials are added and co-precipitated
Data Source
AI summary
A method for preparing a positive electrode active material precursor having a narrow particle size distribution in a reproducible manner. The method utilizes a reaction device in which a reactor and a continuous grinder are connected. The method includes the steps of: (S1) introducing a reaction solution including a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into the reactor to form and discharge a positive electrode active material precursor seed; and (S2) introducing the positive electrode active material precursor seed discharged from the reactor into the continuous grinder, and discharging and re-introducing the positive electrode active material precursor seed into the reactor. Steps (S1) and (S2) are carried out simultaneously.