Bimodal Cathode Precursor Co-Precipitation for Uniform Battery Firing
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Solution Overview
Problem
The existing methods for preparing positive electrode active materials for lithium secondary batteries are costly and time-consuming, particularly due to the need for separate preparation and mixing of small and large-sized particles, which results in unsatisfactory firing uniformity and increased costs.
Innovation Solution
A method for preparing a bimodal positive electrode active material precursor using a single reactor, involving the preparation of first and second aqueous transition metal solutions with different compositions, where doping elements like Zr, B, and W are used to achieve varying particle diameters and compositions, allowing for joint firing and improved firing uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate preparation and mixing of small and large-sized particles is performed, then particle size distribution is improved, but preparation costs and preparation time increase
Solution Approach 1:
The patent combines the preparation of small and large-sized particles into a single simultaneous precipitation process using one reactor. By controlling pH changes and adding complex-forming agents sequentially, both particle sizes are formed together without separate preparation and mixing steps, thereby reducing preparation time and costs while achieving the desired bimodal particle size distribution.
Solution Approach 2:
The patent performs preliminary classification by adding complex-forming agents at specific pH stages during the precipitation process. This preliminary action controls the nucleation and growth of particles at different pH levels, pre-determining the bimodal size distribution before the actual particle formation is complete, which simplifies the overall process.
2Manufacturing precision
If separate preparation and mixing of small and large-sized particles is performed, then particle size distribution is improved, but device complexity increases
Solution Approach 1:
The patent eliminates the need for separate preparation devices and mixing equipment by performing both particle size formations in a single reactor simultaneously. This merging of operations removes the requirement for multiple separation and mixing devices, thereby reducing device complexity while maintaining control over particle size distribution.
Solution Approach 2:
The single reactor is designed to perform multiple functions: it serves as both the nucleation reactor for small particles and the growth reactor for large particles, and also functions as the mixing vessel. This multi-functionality replaces what would traditionally require separate specialized equipment for each operation.
3Manufacturing precision
If appropriate firing temperature varies depending on particle size, then firing uniformity is improved, but preparation costs increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the precursors by introducing different complex-forming agents and doping elements for small and large particles. These parameter changes in composition compensate for the different particle sizes, allowing both sizes to achieve uniform firing characteristics at the same firing temperature, thereby eliminating the need for costly separate firing processes.
Solution Approach 2:
The patent creates composite precursor materials with different compositions tailored to different particle sizes. By incorporating specific complex-forming agents and doping elements into each particle size category during simultaneous precipitation, the resulting composite precursors exhibit complementary properties that enable uniform firing behavior across different particle sizes.
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
This approach reduces preparation costs and time by enabling the synthesis of bimodal precursors with varying particle diameters and compositions, enhancing firing uniformity and simplifying the process, leading to improved capacity and stability of lithium secondary batteries.
Implementation Method 1
performing a precipitation reaction at pH 12 or more to induce the nucleation of a first positive electrode active material precursor particle, and performing a precipitation reaction at less than pH 12 to induce the growth of the first positive electrode active material precursor particle
Implementation Method 2
inputting a first reaction source material including the first aqueous transition metal solution, an ammonium-cation-containing complex-forming agent, and a basic aqueous solution into a reactor, performing a precipitation reaction at pH 12 or more to induce the nucleation of a first positive electrode active material precursor particle
Implementation Method 3
at least one of the first aqueous transition metal solution and the second aqueous transition metal solution contains one or more doping elements selected from among Zr, B, W, Mo, Cr, Al, Ti, Mg, Ta, and Nb
Data Source
AI summary
A method of preparing a bimodal positive electrode active material precursor and a positive electrode active material prepared from the same are disclosed herein. In some embodiments, the method includes inputting a first reaction source material including a first aqueous transition metal solution into a reactor, precipitating at pH 12 or more to induce nucleation of a first positive electrode active material precursor particle, and at less than pH 12 to induce growth of the same, inputting a second reaction source material including a second aqueous transition metal solution into the reactor containing the first positive electrode active material precursor particle, precipitating at pH 12 or more to induce the nucleation of a second positive electrode active material precursor particle, and at less than pH 12 to induce simultaneous growth of the first and second positive electrode active material precursor particles, thereby preparing a bimodal positive electrode active material precursor.