High-Nickel Positive Electrode Material with Surface Phase Shell

Solution Overview

Problem

Lithium nickel cobalt manganese oxide positive electrode active materials for lithium secondary batteries face limitations in structural stability, especially when high nickel content is used to enhance capacity, leading to reduced stability and potential battery rupture and ignition risks.

Innovation Solution

A positive electrode active material with a layered structure center and a secondary phase (spinel or rock-salt structure) on the surface, formed through controlled heat treatment conditions, improving structural stability and thermal stability by limiting the secondary phase to within 30 nm from the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high nickel content is used in lithium nickel cobalt manganese oxide to enhance capacity, then the reversible capacity increases to about 200 mAh/g, but the thermal stability deteriorates and structural stability decreases

Engineering Contradiction:

Improvereversible capacityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the center portion has a layered structure with high nickel content for high capacity, while the surface portion has a spinel or rock-salt secondary phase for thermal and structural stability. This spatial differentiation allows each region to perform its optimal function without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining two different crystal structures (layered structure and spinel/rock-salt secondary phase) within a single particle. The composite structure integrates the high capacity advantage of the layered structure with the thermal stability advantage of the spinel/rock-salt phase.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If high nickel content is used in lithium nickel cobalt manganese oxide to enhance capacity, then the reversible capacity increases to about 200 mAh/g, but the structural stability deteriorates

Engineering Contradiction:

Improvereversible capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the center portion has a layered structure with high nickel content for high capacity, while the surface portion has a spinel or rock-salt secondary phase for thermal and structural stability. This spatial differentiation allows each region to perform its optimal function without compromising the other.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining two different crystal structures (layered structure and spinel/rock-salt secondary phase) within a single particle. The composite structure integrates the high capacity advantage of the layered structure with the thermal stability advantage of the spinel/rock-salt phase.

Inventive Principle:

Principle #40Composite materials

3Use of energy by moving object

If lithium nickel cobalt manganese oxide is used as positive electrode active material, then high energy density is achieved, but the material decomposes under external pressure causing battery rupture and ignition

Engineering Contradiction:

Improveenergy densityVSAvoiddecomposition under pressure

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies beforehand cushioning by forming a protective secondary phase shell on the surface of the high-nickel layered structure before the material is subjected to external pressure or thermal stress. This pre-formed protective layer prevents the harmful decomposition reactions that would otherwise occur under stress conditions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent converts the potential harm of high nickel content (which causes instability) into a benefit by using the same nickel-rich material to form a protective spinel or rock-salt phase on the surface. The potentially harmful material becomes the protective barrier that prevents battery rupture and ignition.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 the structural and thermal stability of the positive electrode active material, resulting in a lithium secondary battery with improved life characteristics and reduced risk of battery rupture, while maintaining high capacity and energy density.

Implementation Method 1

A positive electrode active material with a layered structure center and a secondary phase (spinel or rock-salt structure) on the surface, formed through controlled heat treatment conditions

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS20240063380A1Positive Electrode Active Material for Lithium Secondary Battery, Method of Preparing the Same, and Positive Electrode for Lithium Secondary Battery and Lithium Secondary Battery which Include the Positive Electrode Active Material

Publication Date: 2024.02.22 LG CHEM LTD

AI summary

A method of preparing a positive electrode active material includes mixing a positive electrode active material precursor with a lithium raw material and performing a primary heat treatment, and performing a secondary heat treatment at a temperature lower than that of the primary heat treatment to prepare a positive electrode active material. The primary heat treatment and the secondary heat treatment are respectively performed in an oxygen atmosphere. The secondary heat treatment is performed in the oxygen atmosphere with an oxygen concentration of 50% or more.