Positive Electrode Active Material With Oriented Crystals for Low-Gas Capacity

Solution Overview

Problem

Current lithium secondary battery positive electrode active materials face challenges in improving capacity characteristics and reducing gas generation during charge and discharge, with existing methods limited in representing the entire particle characteristics and varying physical properties based on particle orientation and shape.

Innovation Solution

A positive electrode active material is developed with crystallines having specific major-axis and c-axis orientation ratios, measured using Electron BackScatter Diffraction (EBSD) and scanning ion microscope analysis, to optimize lithium ion mobility and conductivity, comprising lithium composite transition metal oxides with controlled crystalline sizes and micro strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional spherical secondary particles with aggregated primary particles are used, then manufacturing is easier, but capacity characteristics and gas generation control are insufficient

Engineering Contradiction:

Improvecapacity characteristicsVSAvoidparticle structure control

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies local quality by specifying different orientation requirements for different crystalline regions within the particle. The <100> crystal orientation is specifically oriented in the radial direction of the spherical particle, while other regions maintain their natural orientation. This localized orientation control improves capacity characteristics and gas generation control without requiring complete restructuring of the entire particle system.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the crystalline orientation parameter from random distribution to controlled <100> orientation in the radial direction. This parameter change in crystal structure orientation leads to improved lithium ion mobility and electron conductivity, thereby enhancing capacity characteristics while maintaining the spherical particle morphology for ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If TEM analysis is used to analyze primary particle orientation, then particle structure can be observed, but it only provides partial region information rather than entire particle characteristics

Engineering Contradiction:

Improveparticle orientation analysisVSAvoidentire particle characteristics

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent employs XRD analysis as a universal measurement technique that can characterize the entire particle population and provide comprehensive orientation information. Unlike TEM which only analyzes selected regions, XRD gives statistical information about crystal orientations across all particles, eliminating information loss while maintaining measurement precision through diffraction pattern analysis.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If crystalline orientation is not controlled, then manufacturing is simpler, but physical properties vary depending on particle shape and orientation

Engineering Contradiction:

Improvephysical properties consistencyVSAvoidcrystalline structure control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by specifying different orientation requirements for different crystalline regions within the particle. The <100> crystal orientation is specifically oriented in the radial direction of the spherical particle, while other regions maintain their natural orientation. This localized orientation control improves capacity characteristics and gas generation control without requiring complete restructuring of the entire particle system.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the crystalline orientation parameter from random distribution to controlled <100> orientation in the radial direction. This parameter change in crystal structure orientation leads to improved lithium ion mobility and electron conductivity, thereby enhancing capacity characteristics while maintaining the spherical particle morphology for ease of manufacture.

Inventive Principle:

Principle #35Parameter changes

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 enhances capacity characteristics and reduces gas generation in lithium secondary batteries by optimizing the crystalline orientation ratios, leading to improved performance and extended battery life.

Implementation Method 1

a crystalline c-axis orientation degree, which is expressed as a cross product of position unit vector P′ of the crystalline and c-axis rotation vector Rc of a crystal lattice of the crystalline which is obtained through Electron BackScatter Diffraction (EBSD) analysis

Methodology Applied

Scientific EffectElectron BackScatter Diffraction: Diffraction

Data Source

PatentUS20230387405A1Positive Electrode Active Material, and Positive Electrode and Lithium Secondary Battery Which Include the Same

Publication Date: 2023.11.30 LG CHEM LTD

AI summary

A positive electrode active material has crystalline C having a crystalline major-axis orientation degree DoA of 0.5 to 1 and a crystalline c-axis orientation degree of less than 0.5, wherein among total crystallines in a cross section of a positive electrode active material particle, a ratio of the crystalline C is in a range of 25% to 70%. A positive electrode and a lithium secondary battery which include the same are also provided.