Cathode Active Material Structure to Suppress Particle Cracking

Solution Overview

Problem

Lithium secondary batteries face particle cracking issues after cycles due to tungsten adhering only to the surface of positive electrode active materials, leading to performance degradation.

Innovation Solution

A positive electrode active material is developed with a lithium composite metal compound and lithium-containing tungsten oxide, where the tungsten oxide is present in the interparticle spaces and at primary particle boundaries, optimizing pore distribution and composition to suppress particle cracking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tungsten is added to the positive electrode active material to improve battery performance and reduce resistance, then battery capacity and longevity are enhanced, but particle cracking occurs after cycles due to tungsten adhering only to the surface of secondary particles

Engineering Contradiction:

Improvebattery longevityVSAvoidparticle integrity

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies local quality by distributing tungsten oxide at specific locations within the particle structure - both on the surface and in the interparticle spaces between primary particles. This localized distribution ensures that tungsten provides its beneficial effects for battery performance while also being positioned to prevent particle cracking during cycling operations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining the lithium composite metal compound with lithium-containing tungsten oxide. This composite material approach allows the synergistic combination of the high capacity properties of the lithium composite metal compound with the structural stability and conductivity enhancement provided by the tungsten oxide component.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If tungsten is mixed with lithium salt to achieve low resistance, then electrical conductivity is improved, but tungsten adheres only to the surface of secondary particles causing particle cracking after cycles

Engineering Contradiction:

Improveelectrical conductivityVSAvoidparticle integrity

Core Design Contradiction:

Use of energy by moving objectVSStrength

Solution Approach 1:

The patent applies local quality by distributing tungsten oxide at specific locations within the particle structure - both on the surface and in the interparticle spaces between primary particles. This localized distribution ensures that tungsten provides its beneficial effects for battery performance while also being positioned to prevent particle cracking during cycling operations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent utilizes the porous structure created by interparticle spaces within the secondary particles to embed lithium-containing tungsten oxide. This porous material approach allows tungsten to be positioned within the internal structure rather than only on the surface, enabling it to provide both conductivity enhancement and structural support to prevent cracking during battery cycling.

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If tungsten is added to improve battery capacity, then energy storage performance is enhanced, but particle cracking occurs after cycles due to improper tungsten distribution

Engineering Contradiction:

Improvebattery capacityVSAvoidcycle stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by distributing tungsten oxide at specific locations within the particle structure - both on the surface and in the interparticle spaces between primary particles. This localized distribution ensures that tungsten provides its beneficial effects for battery performance while also being positioned to prevent particle cracking during cycling operations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite structure by combining the lithium composite metal compound with lithium-containing tungsten oxide. This composite material approach allows the synergistic combination of the high capacity properties of the lithium composite metal compound with the structural stability and conductivity enhancement provided by the tungsten oxide component.

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3553856B1Positive electrode active material for lithium secondary batteries, positive electrode for lithium secondary batteries, and lithium secondary battery

Publication Date: 2024.02.21 SUMITOMO CHEM CO LTD

Figure 1A~1B
Figure 2~3

AI summary

A positive electrode active material for lithium secondary batteries, includes: a lithium composite metal compound containing secondary particles formed by aggregation of primary particles; and a lithium-containing tungsten oxide, in which the lithium-containing tungsten oxide is present at least in interparticle spaces of the primary particles, and in a pore distribution of the positive electrode active material for lithium secondary batteries measured by a mercury intrusion method, a surface area of pores having a pore diameter in a range of 10 nm or more to 200 nm or less is 0.4 m2/g or more and 3.0 m2/g or less.