Single-Crystal Cathode Material With Sharp Particle Size Distribution
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in achieving uniform particle size distribution and high sharpness of particle size distribution in their positive electrode active materials, which affects the stability and cost-effectiveness of the batteries.
Innovation Solution
A single-crystal type positive electrode active material is developed, which achieves uniform particle size distribution and high sharpness through uniform particle growth induced without harsh calcination conditions and a disintegration process, using a combination of a molten salt-based flux and a metal oxide-based dopant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If harsh calcination conditions are used to induce single crystallization, then the stability of the positive electrode active material is improved, but the particle size distribution becomes non-uniform and agglomeration occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling calcination temperature (700-900°C), holding time (5-20 hours), and atmospheric conditions to achieve single crystallization. This resolves the contradiction by finding optimal parameter ranges that promote uniform particle growth and single-crystal formation without causing agglomeration or non-uniform size distribution, thereby maintaining both stability and manufacturing precision.
Solution Approach 2:
The patent employs preliminary action through a two-stage calcination process where a first calcination forms a precursor structure, followed by a second calcination that completes the single-crystal formation. This preliminary structuring enables uniform particle growth and prevents agglomeration during the final crystallization, achieving both stability and uniform particle size distribution.
2Reliability
If the number of primary particles constituting secondary particles is reduced to improve stability, then lifetime characteristics are improved, but processing costs increase due to disintegration processes
Solution Approach 1:
The patent applies the taking out principle by extracting and eliminating the disintegration step from the conventional manufacturing process. By directly forming single-crystal structures with controlled particle sizes during calcination, the patent removes the need for subsequent mechanical disintegration processes, thereby reducing processing costs while maintaining improved lifetime characteristics.
Solution Approach 2:
The patent employs self-service by designing a calcination process that automatically produces uniformly sized single-crystal particles without requiring external disintegration interventions. The controlled thermal treatment enables particles to self-organize into desired size distributions, eliminating the need for additional processing steps and reducing manufacturing complexity.
3Quantity of substance
If nickel content in lithium composite oxide is increased to maintain high reversible capacity, then discharge capacity is improved, but cation mixing increases and synthesis becomes difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the nickel content within specific ranges (0.8-0.95 mole fraction) and adjusting calcination parameters (temperature, time, atmosphere) to prevent cation mixing. This resolves the contradiction by identifying parameter windows where high nickel content can be maintained for high capacity while synthesis remains feasible and produces uniform single-crystal structures.
Solution Approach 2:
The patent employs composite materials by creating lithium composite oxides with controlled multi-element compositions (Ni, Co, Mn, Al, and optional dopants) that leverage synergistic effects. The composite structure allows high nickel content for capacity while other elements suppress cation mixing and stabilize the crystal structure, making synthesis feasible despite high nickel content.
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 solution results in improved capacity and lifetime characteristics of lithium secondary batteries, while reducing processing costs and minimizing surface defects that can lead to early deterioration.
Implementation Method 1
a lithium composite oxide capable of intercalation/deintercalation of lithium
Implementation Method 2
materials capable of undergoing electrochemical reactions at a positive electrode and a negative electrode
Implementation Method 3
uniform particle growth induced without harsh calcination conditions and a disintegration process, using a combination of a molten salt-based flux and a metal oxide-based dopant
Data Source
AI summary
The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a single-crystal type positive electrode active material which has a uniform particle size distribution and high sharpness of the particle size distribution, and a lithium secondary battery including the same.