Positive Electrode Active Material With Low Ni Disorder

Solution Overview

Problem

Lithium nickel composite transition metal oxides used in lithium secondary batteries face challenges with nickel disorder and thermal stability, leading to reduced particle strength and capacity retention, especially at high temperatures.

Innovation Solution

A positive electrode active material comprising a combination of large-diameter and small-diameter lithium transition metal oxides with specific compositions and crystal grain sizes, where the difference in crystal grain size is minimal, is developed to reduce nickel disorder and enhance particle strength, thereby improving capacity properties and retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a lithium nickel composite metal oxide with high nickel content is used to achieve high reversible capacity, then the battery capacity is improved, but the thermal stability deteriorates and particle strength decreases due to nickel disorder

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 surface region has different composition and properties from the core. The surface is enriched with nickel while the core contains balanced composition, allowing high capacity from nickel-rich surface while maintaining stability from the protected core region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining lithium nickel oxide with coating layers of lithium manganese oxide or lithium iron phosphate. This composite structure allows the high-capacity lithium nickel oxide core to be protected by the thermally stable coating material, resolving the contradiction between capacity and thermal stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If a lithium nickel composite metal oxide with high nickel content is used to achieve high reversible capacity, then the battery capacity is improved, but the particle strength deteriorates due to nickel disorder causing crystal structure variation

Engineering Contradiction:

Improvereversible capacityVSAvoidparticle strength

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the core. The surface is enriched with nickel while the core contains balanced composition, allowing high capacity from nickel-rich surface while maintaining stability from the protected core region.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining lithium nickel oxide with coating layers of lithium manganese oxide or lithium iron phosphate. This composite structure allows the high-capacity lithium nickel oxide core to be protected by the thermally stable coating material, resolving the contradiction between capacity and thermal stability.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If lithium cobalt composite metal oxide is used to achieve high functional voltage and excellent capacity properties, then the battery performance is improved, but the cost increases and thermal properties deteriorate

Engineering Contradiction:

Improvecapacity propertiesVSAvoidcost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by systematically varying the composition ratios of nickel, cobalt, and manganese in the lithium transition metal composite oxide. By optimizing these parameters, the patent achieves high capacity properties while using less expensive nickel-rich compositions compared to traditional lithium cobalt oxide.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining lithium nickel oxide with coating layers of lithium manganese oxide or lithium iron phosphate. This composite structure allows the high-capacity lithium nickel oxide core to be protected by the thermally stable coating material, resolving the contradiction between capacity and thermal stability.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20230420669A1Positive Electrode Active Material, And Positive Electrode And Lithium Secondary Battery Including Same

Publication Date: 2023.12.28 LG ENERGY SOLUTION LTD

AI summary

The present invention relates to a positive electrode active material having low nickel disorder and high particle strength in a crystal structure, and capable of implementing a battery having excellent capacity properties and capacity retention, and a positive electrode and a lithium secondary battery including the same, wherein the positive electrode active material includes a large-diameter lithium transition metal oxide and a small-diameter lithium transition metal oxide whose average particle diameter (D50) is smaller than that of the large-diameter lithium transition metal oxide, wherein the large-diameter lithium transition metal oxide and the small-diameter lithium transition metal oxide each independently have a composition represented by Formula 1, and has a crystal grain size of 100 nm to 150 nm, wherein the difference in crystal grain size between the large-diameter lithium transition metal oxide and the small-diameter lithium transition metal oxide is less than 40 nm, and the positive electrode active material has a nickel disorder (Ni-disorder) of 1.5% or less.