Single-Crystal Cathode Material for High-Temperature Stable Li-Ion Batteries

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Solution Overview

Problem

Lithium-nickel composite oxides (LiNiO2) used in lithium secondary batteries suffer from poor high-temperature stability and potential decomposition due to side reactions with electrolyte solutions, leading to battery swelling and safety risks, while lithium-cobalt composite oxides (LiCoO2) are limited by cost and stability issues, especially in large-capacity applications.

Innovation Solution

A positive electrode active material comprising secondary particles formed from primary lithium-based composite oxide particles with a single crystal structure, reduced specific surface area, and controlled grain boundary density, along with lithium ion diffusion pathways aligned in a single direction, is developed to enhance stability and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium-nickel composite oxide (LiNiO2) is used as positive electrode active material, then reversible capacity is improved (approximately 200 mAh/g), but high-temperature stability deteriorates due to crystal structure instability and side reactions with electrolyte solution

Engineering Contradiction:

Improvereversible capacityVSAvoidhigh-temperature stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by controlling the particle size of LiNiO2 to be 3 μm or less, and adjusting the composition ratio of LiNi1-xMxO2 where M is Mn, Co, or Al with 0.01 ≤ x ≤ 0.40. These parameter optimizations improve high-temperature stability while maintaining high reversible capacity of approximately 200 mAh/g, resolving the contradiction between capacity and stability.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If lithium-cobalt composite oxide (LiCoO2) is used as positive electrode active material, then high-temperature stability and capacity characteristics are improved, but cost deteriorates due to expensive cobalt material

Engineering Contradiction:

Improvehigh-temperature stabilityVSAvoidcost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive cobalt-based materials with cheaper lithium-nickel composite oxide as the base material, then stabilizes it through particle size control and composition adjustment. This substitution maintains high-temperature stability while significantly reducing material cost, addressing the contradiction between stability and manufacturing cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Quantity of substance

If lithium-nickel composite oxide (LiNiO2) is used to achieve high capacity, then energy density is improved, but safety deteriorates due to decomposition by internal pressure and side reactions causing battery rupture or ignition

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent controls critical parameters including particle size (≤3 μm), composition ratio (LiNi1-xMxO2 with 0.01 ≤ x ≤ 0.40), and crystal structure stability. These parameter optimizations prevent decomposition under internal pressure and reduce side reactions with electrolyte, maintaining high energy density while improving safety against rupture and ignition.

Inventive Principle:

Principle #35Parameter changes

4Volume of moving object

If pouch-type secondary battery is used to reduce volume and mass, then portability is improved, but stability deteriorates when inner pressure rapidly increases causing explosion risk

Engineering Contradiction:

Improvebattery volumeVSAvoidpressure stability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent controls particle size of positive electrode active material to be 3 μm or less, which increases surface area and improves electrolyte contact efficiency. This reduces the need for excessive electrolyte volume, thereby reducing overall battery volume and mass while maintaining pressure stability through optimized material properties that prevent gas generation.

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 proposed material maintains high reversible capacity, improves high-temperature stability, reduces gas generation, and enhances safety by minimizing side reactions, thereby ensuring reliable battery performance and stability.

Implementation Method 1

lithium ion diffusion pathways aligned in a single direction

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentEP3663265B1Positive electrode active material for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2025.10.29 ECOPRO BM CO LTD

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AI summary

The present invention relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery including the same. The positive electrode active material according to the present invention reduces the specific surface area and grain boundary of a secondary particle in which a side reaction with an electrolyte solution occurs to improve the high-temperature stability of the positive electrode active material and reduce gas generation caused by the positive electrode active material.