Nickel Composite Hydroxide Crystallization for Uniform Cathode Precursors
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Solution Overview
Problem
Current lithium ion secondary batteries face challenges in achieving high performance due to non-uniform particle size distribution in cathode materials, leading to increased cathode resistance and reduced battery output, with existing manufacturing methods struggling to produce materials with suitable particle size and structure for optimal performance.
Innovation Solution
A nickel composite hydroxide with a controlled particle size distribution is synthesized through a method involving a nucleation process and a particle growth process, where the pH is carefully managed, and the atmosphere is controlled to produce secondary particles with a narrow size distribution and a specific structure, allowing for the formation of either dense or hollow cathode active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cathode material with large particle size is used, then manufacturing is easier, but reaction area with electrolyte is insufficient and reaction resistance increases
Solution Approach 1:
The cathode material particles are segmented into smaller secondary particles (5-15 μm) composed of aggregated primary particles. This segmentation increases the total reaction surface area while maintaining manufacturability through controlled particle formation processes that create uniform secondary particle structures.
Solution Approach 2:
The invention applies local quality by creating a specific particle structure where secondary particles have a controlled size distribution (d90/d10 ≤ 2.0) and internal morphology. The local particle size is optimized to ensure sufficient reaction area at the particle level while maintaining overall particle integrity for easy handling and manufacturing.
2Ease of manufacture
If cathode material with wide particle size distribution is used, then manufacturing is easier, but voltage applied to particles is not uniform and capacity decreases
Solution Approach 1:
The invention changes the particle size distribution parameters by controlling the d90/d10 ratio to be 2.0 or less. This parameter control ensures uniform voltage application across particles during charging and discharging, preventing selective deterioration of minute particles while maintaining ease of manufacture through scalable production processes.
Solution Approach 2:
The manufacturing process incorporates feedback control by monitoring and adjusting particle formation conditions to achieve the target particle size distribution. The d90/d10 ratio serves as a key feedback parameter to ensure uniform particle sizes are achieved consistently in production, linking manufacturing ease with particle uniformity.
3Power
If particle size is reduced to increase reaction area, then output improves, but particle size uniformity becomes harder to control
Solution Approach 1:
The invention transitions from controlling only particle size to controlling the relationship between d90 and d10 values (d90/d10 ratio). This dimensional change in the control parameter space allows optimization of particle size for high output (5-15 μm secondary particles) while simultaneously maintaining uniformity through the ratio constraint, resolving the trade-off between power and manufacturing precision.
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 cathode active material exhibits improved uniformity, reduced cathode resistance, and enhanced battery performance, including higher capacity and output, with the manufacturing method being suitable for large-scale industrial production.
Implementation Method 1
a method for producing nickel composite hydroxide by a crystallization reaction
Implementation Method 2
a nucleation process that performs nucleation by controlling a nucleation aqueous solution
Implementation Method 3
a particle growth process that causes nuclei to grow by controlling a particle growth aqueous solution
Data Source
AI summary
Provided are a cathode active material having a suitable particle size and high uniformity, and a nickel composite hydroxide as a precursor of the cathode active material. When obtaining nickel composite hydroxide by a crystallization reaction, nucleation is performed by controlling a nucleation aqueous solution that includes a metal compound, which includes nickel, and an ammonium ion donor so that the pH value at a standard solution temperature of 25° C. becomes 12.0 to 14.0, after which, particles are grown by controlling a particle growth aqueous solution that includes the formed nuclei so that the pH value at a standard solution temperature of 25° C. becomes 10.5 to 12.0, and so that the pH value is lower than the pH value during nucleation. The crystallization reaction is performed in a non-oxidizing atmosphere at least in a range after the processing time exceeds at least 40% of the total time of the particle growth process from the start of the particle growth process where the oxygen concentration is 1 volume % or less, and with controlling an agitation power requirement per unit volume into a range of 0.5 kW/m3 to 4 kW/m3 at least during the nucleation process.