Cathode Active Material Composition for Mixed-Particle Heat Treatment
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Solution Overview
Problem
Existing cathode active materials for lithium secondary batteries face challenges in achieving optimal performance due to differing optimal heat treatment temperatures for coarse and fine particles, leading to suboptimal capacity and life characteristics.
Innovation Solution
A cathode active material composition is developed with particles of different sizes and nickel compositions, where the nickel content of fine particles is adjusted to be 5% less than that of coarse particles, and both types are heat-treated at the same temperature, maintaining an optimal capacity manifestation temperature for both.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fine particles and coarse particles are mixed to increase energy density, then capacity is improved, but optimal heat treatment temperature cannot be satisfied for both particle types
Solution Approach 1:
The patent applies local quality by creating particles with different nickel compositions within the same cathode active material. Fine particles have a first nickel composition while coarse particles have a second nickel composition, allowing each particle size to be optimized for its specific heat treatment temperature requirements. This enables fine particles to achieve optimal capacity at lower temperatures while coarse particles require higher temperatures, resolving the temperature contradiction.
Solution Approach 2:
The patent changes the nickel composition parameter to control heat treatment temperature requirements. By adjusting the nickel content in fine particles versus coarse particles, the patent creates a gradient where fine particles with lower nickel content require lower heat treatment temperatures, while coarse particles with higher nickel content require higher temperatures. This parameter change allows both particle types to be processed simultaneously or separately at their respective optimal temperatures.
2Quantity of substance
If nickel composition is increased to enhance capacity, then energy density is improved, but heat treatment temperature range becomes narrower
Solution Approach 1:
The patent segments the cathode active material into fine particles and coarse particles with different nickel compositions. This segmentation allows each fraction to have an optimized nickel content that provides both high capacity and an appropriate heat treatment temperature range. Fine particles with lower nickel content have broader temperature tolerance, while coarse particles with higher nickel content achieve higher energy density at elevated 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
This approach enhances the output and life characteristics of lithium secondary batteries by ensuring both particle types exhibit optimal performance, resulting in improved discharge capacity and extended cycle life.
Implementation Method 1
Since a specific surface area of the fine particles is larger than that of the coarse particle, the fine particles may absorb a larger amount of lithium even at a relatively low heat treatment temperature
Data Source
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AI summary
The present invention relates to a cathode active material composition for a lithium secondary battery and a lithium secondary battery including the same, and more particularly, to a cathode active material composition for a lithium secondary battery, including a mixture of particles which are different in Ni composition and size and prepared at the same heat treatment temperature, and a lithium secondary battery including the same. According to the present invention, optimal capacity manifestation temperatures of a coarse particle and a fine particle may be adjusted to be similar by adjusting an Ni content of the coarse particle and the fine particle, and thus, a lithium secondary battery having enhanced output and lifetime may be manufactured.