Nickel Composite Hydroxide pH Control for Uniform Cathode Particles
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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 active materials, leading to increased reaction resistance and reduced battery output.
Innovation Solution
A nickel composite hydroxide with highly uniform particle size distribution is synthesized through a method that separates nucleation and particle growth processes, allowing for the formation of secondary particles with a narrow size distribution and a hollow structure, which enhances the specific surface area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional co-precipitation method is used to manufacture composite hydroxide, then manufacturing process is simple, but particle size distribution is wide and non-uniform
Solution Approach 1:
The patent divides the particle formation process into two distinct stages: nucleation process and particle growth process. The nucleation process creates uniform nuclei at controlled pH 12.0-14.0, while the particle growth process allows these nuclei to grow to final size at lower pH 10.5-12.0. This segmentation enables precise control over particle size distribution, achieving a narrow distribution with d90/d10 ratio of 1.20 or less, while maintaining industrial feasibility through continuous processing.
2Power
If cathode material has large particle size, then manufacturing is easier, but reaction resistance increases and battery output decreases
Solution Approach 1:
The patent controls the pH parameter throughout the manufacturing process to achieve optimal particle size. By maintaining pH 12.0-14.0 during nucleation and then adjusting to pH 10.5-12.0 during growth, the process produces particles with average size 5-15 μm and narrow distribution. This parameter control enables the cathode material to have sufficiently small particle size for low reaction resistance and high battery output, while the particles remain large enough for practical manufacturing and electrode fabrication.
3Stability of the object's composition
If cathode material has wide particle size distribution, then manufacturing flexibility is improved, but voltage uniformity during charging/discharging deteriorates
Solution Approach 1:
The patent implements feedback control by monitoring and controlling pH levels at different stages of the process. The pH is maintained within specific ranges (12.0-14.0 during nucleation, then 10.5-12.0 during growth) to ensure uniform particle formation. This feedback mechanism guarantees that the resulting cathode material has narrow particle size distribution, which ensures uniform voltage application and prevents selective deterioration of fine particles during repeated charging and discharging cycles.
4Power
If specific surface area is increased to reduce reaction resistance, then battery output improves, but particle size becomes smaller and more difficult to manufacture
Solution Approach 1:
The patent employs periodic action by sequentially executing the nucleation process followed by the particle growth process. First, uniform nuclei are formed at high pH 12.0-14.0, then the pH is reduced to 10.5-12.0 to allow controlled growth. This periodic, two-stage approach achieves the optimal balance: particles with average size 5-15 μm and narrow distribution that provide sufficient specific surface area for low reaction resistance and high battery output, while maintaining manufacturability through industrial-scale continuous 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 resulting cathode active material exhibits improved battery characteristics, including reduced cathode resistance, increased output, and enhanced cycle stability, making it suitable for high-performance lithium ion secondary batteries.
Implementation Method 1
a nucleation process that performs nucleation by controlling a nucleation aqueous solution
Implementation Method 2
The present invention relates to a method for manufacturing nickel composite hydroxide by a crystallization reaction
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.