Positive Electrode Active Material with Narrow Particle Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Positive electrode active materials for nonaqueous electrolyte secondary batteries face challenges in achieving high output characteristics and durability due to particle cracking and expansion issues during charge and discharge cycles, particularly in large-sized power applications like electric vehicles.
Innovation Solution
A method involving the production of nickel-containing composite oxide particles with a specific particle size distribution, followed by heat treatments and dispersion treatments to create lithium-transition metal composite oxide particles with a uniform particle size and reduced grain boundaries, as represented by the formula Li1pNixCoyM1zO2+α, where 1.0≤p≤1.3, 0.3≤x<0.6, 0≤y≤0.4, 0≤z≤0.5, and −0.1 ≤α≤0.1, and M1 represents at least one of Mn and Al.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the size of aggregated primary particles in secondary particles is reduced to increase BET specific surface area, then output characteristics are improved, but cracks occur in secondary particles due to pressurization and expansion/shrinkage, reducing durability
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution of secondary particles (1D90/1D10 ratio of 2.0 or less) and the composition ratio of lithium to transition metals (1.0 ≤ p ≤ 1.3). This optimization allows the material to achieve high output characteristics while maintaining structural integrity during charge-discharge cycles, preventing crack formation and improving durability.
Solution Approach 2:
The patent uses composite materials by creating lithium-transition metal composite oxide with a specific layered structure where lithium ions are interspersed among transition metal atoms. This composite structure provides both high surface area for power output and structural stability to prevent cracking during volume changes.
2Power
If secondary particles are formed by aggregating a large number of primary particles to increase BET specific surface area, then output characteristics are improved, but manufacturing complexity increases due to multiple heat treatment steps required
Solution Approach 1:
The patent applies preliminary action by pre-forming secondary particles with the desired size distribution (1D90/1D10 ≤ 2.0) before the heat treatment process. This allows the subsequent heat treatment to focus solely on forming the lithium-transition metal composite oxide structure without needing additional grinding or size adjustment steps, thereby simplifying the manufacturing process.
3Power
If particle size of secondary particles is reduced to improve output characteristics, then power performance is improved, but particle cracking occurs during charge and discharge, reducing capacity retention
Solution Approach 1:
The patent optimizes the particle size parameters by controlling the 1D90/1D10 ratio to 2.0 or less, ensuring a narrow size distribution. This parameter control allows smaller particles to be used for high power output while the uniformity prevents stress concentration and cracking, thereby maintaining capacity retention over multiple charge-discharge cycles.
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 lithium-transition metal composite oxide particles with improved output characteristics and durability, reducing particle cracking and maintaining high power performance while ensuring electrode filling properties and capacity retention.
Implementation Method 1
subjecting the first mixture to a first heat treatment at a first temperature and a second heat treatment at a second temperature higher than the first temperature
Data Source
AI summary
A method of producing a positive electrode active material for a nonaqueous electrolyte secondary battery, the method includes preparing nickel-containing composite oxide particles having a ratio 1D90/1D10 of a 90% particle size 1D90 to a 10% particle size 1D10 in volume-based cumulative particle size distribution is 3 or less; mixing the composite oxide particles and a lithium compound to obtain a first mixture; subjecting the first mixture to a first heat treatment at a first temperature and a second heat treatment at a second temperature higher than the first temperature to obtain a first heat-treated product; and subjecting the first heat-treated material to a dispersion treatment.