Oriented Cathode Active Material Using Density Gradient Precursors
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Solution Overview
Problem
Conventional cathode active materials for lithium batteries face challenges in achieving a complete orientation from the inside to the surface of particles, leading to high processing costs and difficulty in quality control, while also being limited by high cobalt content and recent price increases, which affect rate characteristics and lifespan.
Innovation Solution
A cathode active material with an oriented structure is prepared by firing a density gradient precursor, where the density gradually changes from the inside to the outside of secondary particles formed from aggregated primary particles, using xylitol as a particle shape controller to enhance capacity and lifespan characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a concentration gradient structure is implemented in cathode active materials, then stability is improved, but manufacturing complexity increases and quality control becomes difficult
Solution Approach 1:
The patent applies parameter changes by controlling the concentration of transition metal components (Ni, Co, Mn) as a gradient from the particle center to surface, and by controlling particle density as a gradient. This creates the oriented structure that improves stability while using a relatively simple firing process to achieve the concentration gradient, thus resolving the contradiction between reliability improvement and manufacturing complexity.
2Reliability
If cobalt content is increased to improve rate characteristics, then performance is improved, but cost increases
Solution Approach 1:
The patent applies local quality by creating different chemical compositions at different locations within the particle. The center region has a different transition metal component concentration compared to the surface region, allowing optimized rate characteristics in the interior while controlling overall cobalt content to reduce cost. This enables performance optimization without uniformly increasing expensive cobalt throughout the entire material.
3Manufacturing precision
If orientation is incomplete in cathode active materials, then processing costs are high, but if orientation is complete, then quality control becomes difficult
Solution Approach 1:
The patent applies self-service by utilizing the natural diffusion process during firing to automatically create the density gradient and oriented structure. The density gradient precursor spontaneously forms the desired orientation through thermal diffusion without requiring additional complex processing steps, enabling complete orientation while maintaining relatively simple manufacturing and easier quality control through inherent process stability.
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 oriented structure reduces lithium migration resistance, improving the output characteristics and lifespan of lithium secondary batteries while reducing processing costs and enhancing quality control.
Implementation Method 1
the density gradient is diffused during firing and the density gradually changes from the inside of the secondary particle to the outside of the secondary particle
Data Source
AI summary
The present invention relates to a lithium battery cathode active material and a preparation method therefor, the material having an orientation formed by firing a density gradient precursor in which the density gradually changes from the inside of second particles, formed as an aggregate of primary particles, to the outside of the particles. The lithium battery cathode active material according to the present invention has an oriented structure, and thus can have a long lifespan and high capacity characteristics.