Composite Hydroxide Precipitation to Prevent Calcination Sintering
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Solution Overview
Problem
The sintering of secondary particles during high-temperature calcination in the production of nickel-cobalt composite hydroxides leads to decreased packing properties in positive electrode active materials, necessitating additional pulverization steps.
Innovation Solution
A method of producing a composite hydroxide by controlling pH and ammonium ion concentration during nucleation and growth stages to prevent secondary particle sintering, resulting in secondary particles with specific crystallite sizes and random primary particle aggregation, which are then calcined without further pulverization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature calcination is performed to obtain secondary particles with small number of primary particles aggregated, then durability with regard to cracking of particles is improved, but secondary particles are sintered in aggregated state leading to decreased packing property
Solution Approach 1:
The invention controls specific parameters during precipitation: pH 12.0-13.5 during nucleus generation, pH 9.7-10.8 during nucleus growth, temperature 25-40°C, and ammonium ion concentration 5.3-11.7 g/L. These parameter controls create secondary particles with specific structures (crystallite size Sp 300-500 nm, Sv 100-300 nm, Lp/Lv ratio 10 or more) that resist sintering during calcination, thus maintaining both durability and packing property
Solution Approach 2:
The invention creates composite hydroxide particles with specific internal structure consisting of multiple primary particles aggregated into secondary particles with controlled morphology. This composite structure with anisotropic crystallite growth (Lp/Lv ≥ 10) provides both mechanical durability and resistance to sintering, allowing the material to maintain particle integrity and packing density after high-temperature calcination
2Reliability
If high-temperature calcination is performed to improve particle durability, then cracking resistance is improved, but additional pulverization step is required to restore packing property
Solution Approach 1:
By precisely controlling precipitation parameters (pH 12.0-13.5 for nucleus generation, pH 9.7-10.8 for nucleus growth, temperature 25-40°C, ammonium ion concentration 5.3-11.7 g/L), the invention creates secondary particles with specific crystallite structure (Sp 300-500 nm, Sv 100-300 nm, Lp/Lv ≥ 10) that inherently resist sintering. This eliminates the need for pulverization steps after calcination, maintaining productivity while achieving durability
Solution Approach 2:
The invention performs preliminary structuring of secondary particles during the precipitation process itself, creating anisotropic crystallite growth and controlled aggregation patterns before calcination. This preliminary action prepares the particles to withstand high-temperature treatment without sintering, eliminating the need for subsequent pulverization to restore packing properties
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 enhances packing properties in positive electrode active materials by suppressing secondary particle sintering, reducing the need for additional processing steps and improving reactivity with lithium.
Implementation Method 1
by supplying an aqueous ammonia solution and sodium hydroxide to an aqueous solution including a compound containing nickel and a compound containing manganese, generating a nucleus while maintaining a pH at 12.0 to 13.5
Implementation Method 2
generating a nucleus while maintaining a pH at 12.0 to 13.5 on condition of a liquid temperature of 25° C. and an ammonium ion concentration at 5.3 to 11.7 g/L
Implementation Method 3
growing the nucleus while maintaining the pH at 9.7 to 10.8 on condition of the liquid temperature of 25° C. and the ammonium ion concentration at 20.0 to 26.4 g/L
Implementation Method 4
growing the nucleus while maintaining the pH at 9.7 to 10.8
Implementation Method 5
a method of producing a composite oxide, the method comprising the method of producing a composite hydroxide
Data Source
AI summary
A method of producing a composite hydroxide according to the present disclosure includes: by supplying an aqueous ammonia solution and sodium hydroxide to an aqueous solution including a compound containing nickel and a compound containing manganese, generating a nucleus while maintaining a pH at 12.0 to 13.5 on condition of a liquid temperature of 25° C. and an ammonium ion concentration at 5.3 to 11.7 g/L; and growing the nucleus while maintaining the pH at 9.7 to 10.8 on condition of the liquid temperature of 25° C. and the ammonium ion concentration at 20.0 to 26.4 g/L.