Low-Cobalt Cathode Particle Composition for High-Temperature Battery Life

Solution Overview

Problem

Lithium secondary batteries face challenges with high-temperature storage stability and lifespan due to the instability of lithium metal oxide particles lacking cobalt, which increases manufacturing costs and reduces performance.

Innovation Solution

A cathode for lithium secondary batteries is designed with lithium metal oxide particles having a cobalt mole fraction of 0.02 or less, featuring specific particle size distributions and compositions to enhance stability, including a mix of secondary and single particle shapes, and incorporating conductive and binder materials to optimize packing and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If lithium metal oxide particles excluding cobalt are used, then manufacturing cost is reduced, but high-temperature storage stability and lifespan characteristics are deteriorated

Engineering Contradiction:

Improvemanufacturing costVSAvoidhigh-temperature storage stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the particle core contains low-cobalt lithium metal oxide for cost reduction, while the surface shell contains high-cobalt lithium metal oxide for stability. This spatial differentiation of composition allows the interior to provide cost benefits while the exterior provides protective stability against high-temperature degradation and lifespan deterioration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining two different lithium metal oxide compositions within the same particle structure. The composite consists of a low-cobalt core region and a high-cobalt surface region, creating a multi-phase composite material that simultaneously achieves cost reduction and performance maintenance through the synergistic combination of different compositional zones.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If lithium metal oxide particles excluding cobalt are used, then manufacturing cost is reduced, but lifespan characteristics are deteriorated

Engineering Contradiction:

Improvemanufacturing costVSAvoidlifespan characteristics

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the particle core contains low-cobalt lithium metal oxide for cost reduction, while the surface shell contains high-cobalt lithium metal oxide for stability. This spatial differentiation of composition allows the interior to provide cost benefits while the exterior provides protective stability against high-temperature degradation and lifespan deterioration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies beforehand cushioning by pre-forming a protective high-cobalt surface layer on the low-cobalt particles before battery assembly. This surface shell acts as a protective barrier that cushions the low-cobalt core against chemical degradation and structural collapse during cycling, thereby extending lifespan while maintaining cost benefits from the low-cobalt composition.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If nickel-containing lithium metal oxide particles with low cobalt content are used, then cost is reduced and capacity is enhanced, but operational stability and chemical stability are deteriorated

Engineering Contradiction:

ImprovecapacityVSAvoidoperational stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the particle core contains low-cobalt lithium metal oxide for cost reduction, while the surface shell contains high-cobalt lithium metal oxide for stability. This spatial differentiation of composition allows the interior to provide cost benefits while the exterior provides protective stability against high-temperature degradation and lifespan deterioration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies intermediary by using the high-cobalt surface shell as a mediator between the low-cobalt core particles and the external battery environment. This intermediate layer protects the high-capacity low-cobalt core from direct exposure to electrolyte and operational stress, thereby maintaining operational and chemical stability while preserving the capacity benefits of the nickel-rich low-cobalt composition.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP4369433A1Cathode for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2024.05.15 SK INNOVATION CO LTD

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AI summary

A cathode for a lithium secondary battery according to exemplary embodiments may include a cathode current collector and a cathode active material layer which is formed on the cathode current collector, includes cathode active material particles and satisfies a specific equation. The cathode active material particles may include lithium metal oxide particles which contain nickel and have a mole fraction of cobalt of 0.02 or less of all elements except for lithium and oxygen.