Composite Cathode Active Material for Crack-Resistant Li-Ion Cycling

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Solution Overview

Problem

Rechargeable lithium batteries face issues with cracks during charging and discharging due to side reactions between the positive electrode active material and electrolyte, leading to reduced safety and performance, particularly in high-capacity applications.

Innovation Solution

A positive electrode active material comprising a lithium nickel-cobalt-aluminum-based composite oxide with radially oriented primary particles and a lithium nickel-cobalt-aluminum-manganese-based composite oxide with smaller secondary particles, prepared through a co-firing process that allows for aluminum diffusion, enhancing structural stability and cycle-life characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high nickel-based positive electrode active materials are used to increase capacity, then battery capacity is improved, but cracks occur inside particles during charging and discharging leading to reduced cycle-life characteristics

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle-life characteristics

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The positive electrode active material is divided into a composite structure consisting of multiple types of particles (first type with lithium nickel-cobalt-aluminum oxide, second type with lithium nickel-cobalt-aluminum-manganese oxide) of different sizes. This segmentation allows each particle type to contribute differently, with smaller particles providing structural stability and larger particles providing capacity, thereby resolving the contradiction between high capacity and long cycle-life.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode active material have different compositions and properties. The first type of particle (larger size) provides high capacity while the second type of particle (smaller size) provides structural stability and crack resistance. This local differentiation of material properties allows the overall material to achieve both high capacity and long cycle-life characteristics simultaneously.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If large and small particles of different particle sizes are mixed to increase energy density, then energy density is improved, but cracks occur inside particles during long-term cycling

Engineering Contradiction:

Improveenergy densityVSAvoidparticle structural integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The invention uses a composite material system where first type particles (lithium nickel-cobalt-aluminum oxide) and second type particles (lithium nickel-cobalt-aluminum-manganese oxide) are combined in specific proportions. The smaller second type particles act as structural stabilizers that prevent cracking in the larger first type particles during cycling, thus maintaining particle structural integrity while achieving high energy density through the size distribution.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If high nickel-based positive electrode active materials are used, then capacity is improved, but side reactions with electrolyte solution increase leading to gas generation and reduced safety

Engineering Contradiction:

Improvebattery capacityVSAvoidside reactions with electrolyte

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention creates local quality differentiation by incorporating second type particles (lithium nickel-cobalt-aluminum-manganese oxide) with smaller size and different composition into the system. These particles have enhanced stability and reduced reactivity with electrolyte, locally suppressing side reactions and gas generation while the first type particles (lithium nickel-cobalt-aluminum oxide) maintain high capacity functionality.

Inventive Principle:

Principle #3Local quality

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 active material achieves high capacity, high initial charge and discharge efficiency, and excellent cycle-life characteristics, improving the safety and performance of rechargeable lithium batteries.

Implementation Method 1

at least a portion of the primary particles is oriented radially

Methodology Applied

Scientific EffectRadial orientation:

Implementation Method 2

performing heat treatment, wherein an average particle diameter of the first positive electrode active material precursor is larger than an average particle diameter of the second positive electrode active material precursor

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20260015254A1Positive electrode active materials for rechargeable lithium batteries, preparation methods thereof, and rechargeable lithium batteries

Publication Date: 2026.01.15 SAMSUNG SDI CO LTD

AI summary

Disclosed are a positive electrode active material for a rechargeable lithium battery, a preparation method thereof and a rechargeable lithium battery, the positive electrode active material for a rechargeable lithium battery including a first positive electrode active material in a form of secondary particles including a lithium nickel-cobalt-aluminum-based composite oxide and formed by agglomerating a plurality of primary particles, wherein at least a portion of the primary particles is oriented radially; and a second positive electrode active material in a form of secondary particles including a lithium nickel-cobalt-aluminum-manganese-based composite oxide, and formed by agglomerating a plurality of primary particles, wherein an average particle diameter of secondary particles of the first positive electrode active material is larger than an average particle diameter of the secondary particles of the second positive electrode active material.