Lithium Cobaltate Particle Density Control via Cobalt Oxyhydroxide Precursor
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Solution Overview
Problem
Current lithium cobaltate particles for secondary batteries face challenges in achieving high packing density, small specific surface area, and stable crystal structure, leading to issues with cycle characteristics, thermal stability, and electrode density.
Innovation Solution
Cobalt oxyhydroxide particles with controlled average secondary particle diameter, BET specific surface area, and tap density are produced using a specific process involving pH adjustment and oxidation, resulting in lithium cobaltate particles with improved compressed density and crystal growth, which are then used to form positive electrodes with enhanced properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium is released from LiCoO2 to increase charge/discharge capacity, then the charge/discharge capacity is improved, but the crystal structure suffers from Jahn-Teller distortion leading to unstable characteristics
Solution Approach 1:
The patent applies parameter changes by controlling the particle size, specific surface area, and crystallite orientation of LiCoO2 through a specific manufacturing process. By optimizing these parameters (particle diameter of 5-15 μm, specific surface area of 0.15-0.6 m²/g, and controlled crystallite sizes), the material achieves both high charge/discharge capacity and structural stability, preventing Jahn-Teller distortion during lithium release.
2Quantity of substance
If the packing density of lithium cobaltate is increased to achieve high electrode density, then the electrode capacity is improved, but the specific surface area increases leading to battery swelling and reduced thermal stability
Solution Approach 1:
The patent resolves this contradiction by precisely controlling multiple parameters simultaneously: particle size (5-15 μm), specific surface area (0.15-0.6 m²/g), and tap density (1.8-2.2 g/cm³). This optimized parameter set achieves high electrode density while maintaining low specific surface area, thereby preventing battery swelling and improving thermal stability.
Solution Approach 2:
The patent applies preliminary action by pre-controlling the particle morphology and size distribution of lithium cobaltate before electrode fabrication. The manufacturing process produces particles with predetermined optimal characteristics, ensuring that when the electrode is assembled, the high density is achieved without excessive specific surface area that would cause swelling.
3Speed
If the reactivity of lithium cobaltate with electrolyte solution is increased at high temperature to improve charge/discharge rate, then the charge/discharge rate is improved, but the thermal stability decreases leading to safety issues
Solution Approach 1:
The patent applies parameter changes by optimizing the crystallite size and orientation of lithium cobaltate. By controlling the crystallite dimensions (a-axis: 0.3-0.7 μm, c-axis: 0.1-0.3 μm) and specific surface area, the material achieves appropriate reactivity for good charge/discharge rates while maintaining thermal stability through reduced surface area that would otherwise react excessively with the electrolyte at high temperatures.
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 lithium cobaltate particles exhibit improved cycle characteristics, thermal stability, and high electrode density, reducing battery swelling and maintaining capacity, while the production process minimizes environmental impact by avoiding ammonia use.
Implementation Method 1
rapidly conducting an oxidation reaction of the cobalt salt by passing an oxygen-containing gas or a mixed gas of an oxygen-containing gas and a nitrogen-containing gas through the aqueous solution
Implementation Method 2
calcining the resulting mixture
Data Source
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AI summary
The present invention relates to cobalt oxyhydroxide particles and lithium cobaltate particles which have a high density and a uniformly grown crystal structure. These objects of the present invention can be achieved by cobalt oxyhydroxide particles having an average secondary particle diameter (D50) of 3.0 to 25.0 µm, a BET specific surface area (BET) of 0.1 to 20.0 m2/g, a tap density (TD) of 1.0 to 3.5 g/cm3 in which the average secondary particle diameter (D50) and the BET specific surface area (BET) of the cobalt oxyhydroxide particles satisfy the relational formula; and by lithium cobaltate particles having an average secondary particle diameter (D50) of 15.0 to 25.0 µm, a specific surface area (BET) of 0.10 to 0.30 m2/g, a compressed density (CD; as measured by applying a pressure of 2.5 t/cm2 thereto) of 3.65 to 4.00 g/cm3. The cobalt oxyhydroxide particles are useful as a precursor of a positive electrode active substance (lithium cobaltate particles) used in a non-aqueous electrolyte secondary battery, and the lithium cobaltate particles are useful as a the positive electrode active substance used in a non-aqueous electrolyte secondary battery.