Tungsten-Surface Cathode Hydroxide for Low-Resistance Li-Ion Output
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Solution Overview
Problem
Existing methods for producing positive electrode active materials for lithium-ion batteries face issues such as non-uniform coating of tungsten, increased reaction resistance, and deteriorated cycle characteristics, which hinder the achievement of high output and crystallinity.
Innovation Solution
A two-stage crystallization process is employed to produce a metal composite hydroxide with a tungsten-concentrated layer on its surface, followed by mixing with a lithium compound to form a lithium-metal composite oxide, ensuring uniform tungsten distribution and high crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-stage crystallization process is used to produce metal composite hydroxide with tungsten-concentrated layer, then uniform tungsten distribution and high crystallinity are achieved, but the manufacturing process complexity increases
Solution Approach 1:
The crystallization process is divided into two distinct stages: a first crystallization process that forms the base metal composite hydroxide structure, and a second crystallization process that forms the tungsten-concentrated layer on the surface. This segmentation allows each stage to be optimized independently, achieving uniform tungsten distribution without requiring complete process redesign.
Solution Approach 2:
The first crystallization process prepares the substrate structure in advance, creating metal composite hydroxide particles with specific surface properties that facilitate subsequent tungsten layer formation. This preliminary action ensures that when the second crystallization process occurs, tungsten distributes uniformly on the pre-formed surface structure.
2Power
If tungsten is added to decrease reaction resistance and improve output characteristics, then battery output increases, but non-uniform coating and increased reaction resistance occur
Solution Approach 1:
The patent controls the concentration of tungsten in the second raw material aqueous solution and adjusts pH conditions during the second crystallization process. By changing these parameters, the tungsten concentration at the particle surface is controlled to form a uniform concentrated layer rather than non-uniform coating, achieving both improved output characteristics and uniform distribution.
Solution Approach 2:
Tungsten is concentrated specifically on the surface layer of the metal composite hydroxide particles rather than being uniformly distributed throughout the bulk material. This local concentration at the surface provides the desired low reaction resistance and high output characteristics while maintaining uniform distribution across all particles.
3Area of stationary object
If particle size is reduced to increase specific surface area and improve output, then reaction area with electrolyte increases, but particle size control and uniformity become difficult
Solution Approach 1:
The crystallization process is segmented into nucleation and growth phases with distinct pH conditions. The first crystallization process controls nucleation to form numerous small particles, while the second process allows controlled growth with tungsten layer formation. This segmentation enables precise particle size control while maximizing specific surface area.
Solution Approach 2:
The patent employs pH monitoring and control during both crystallization processes to maintain particles within a specific size range (0.1-10 μm). By using pH as a feedback control parameter, the process ensures uniform particle size distribution while achieving high specific surface area, preventing both excessive growth and aggregation.
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 with reduced reaction resistance and enhanced output characteristics, suitable for high-energy density secondary batteries.
Implementation Method 1
a first crystallization process of performing crystallization by supplying a first raw material aqueous solution containing metal salts and an ammonium ion donor into a reaction tank
Implementation Method 2
performing crystallization by supplying a first raw material aqueous solution containing metal salts and an ammonium ion donor into a reaction tank
Implementation Method 3
supplying a second raw material aqueous solution containing a larger amount of tungsten than the first raw material aqueous solution and an ammonium ion donor into the reaction aqueous solution
Data Source
AI summary
A method for producing a metal composite hydroxide, which includes a first crystallization process of obtaining first metal composite hydroxide particles by supplying a first raw material aqueous solution containing a metal element and an ammonium ion donor to a reaction tank, adjusting a pH of a reaction aqueous solution in the reaction tank, and performing a crystallization reaction and a second crystallization process of forming a tungsten-concentrated layer on a surface of the first metal composite hydroxide particles and obtaining second metal composite hydroxide particles by supplying a second raw material aqueous solution containing a metal element and a more amount of tungsten than the first raw material aqueous solution and an ammonium ion donor to a reaction aqueous solution containing the first metal composite hydroxide particles, adjusting a pH of the reaction aqueous solution, and performing a crystallization reaction, and the like.