Core-Shell Cathode Active Material for Conductive Slurry Dispersion

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Solution Overview

Problem

The poor dispersion of carbon-based conductive materials in cathode slurries for lithium secondary batteries leads to deteriorated conductivity due to particle aggregation, affecting the electrical properties and reliability of the batteries.

Innovation Solution

A cathode active material with a core-shell structure is developed, comprising a lithium metal oxide core and a reduced carbon nanotube oxide shell, where the shell portion covers at least 70% of the core's surface area, enhancing electrical conductivity without the need for additional conductive materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbon-based conductive material is added to cathode slurry, then electrical conductivity is improved, but particle aggregation occurs due to high specific surface area and van der Waals force, resulting in poor dispersion

Engineering Contradiction:

Improveelectrical conductivityVSAvoiddispersion uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent uses carbon nanotube oxide as an intermediary substance that bridges the conductive material and lithium metal oxide. The carbon nanotube oxide forms a shell around the lithium metal oxide core, creating a core-shell structure that improves electrical conductivity while preventing aggregation. The intermediary carbon nanotube oxide layer prevents direct contact between conductive material particles, eliminating van der Waals attraction while maintaining conductive pathways.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite cathode active material consisting of lithium metal oxide core and carbon nanotube oxide shell. This composite structure combines the high conductivity of carbon nanotubes with the electrochemical activity of lithium metal oxide, achieving both improved electrical conductivity and stable dispersion. The composite nature prevents particle aggregation while maintaining the functional properties of both materials.

Inventive Principle:

Principle #40Composite materials

2Reliability

If carbon-based conductive material is used in cathode fabrication, then electrical property is enhanced, but manufacturing complexity increases due to dispersion control requirements

Engineering Contradiction:

Improveelectrical propertyVSAvoidfabrication simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent performs preliminary action by pre-forming the core-shell structured cathode active material particles before cathode fabrication. The carbon nanotube oxide shell is already formed on the lithium metal oxide core, so when these pre-structured particles are mixed into the cathode slurry, they automatically maintain stable dispersion without requiring additional dispersion control measures during cathode manufacturing. This preliminary structuring simplifies the overall fabrication process.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If shell portion covers larger surface area of core portion, then electrical conductivity is improved, but material content of lithium metal oxide is reduced

Engineering Contradiction:

Improveelectrical conductivityVSAvoidlithium metal oxide content

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent employs a thin film shell of carbon nanotube oxide that covers the lithium metal oxide core. The shell thickness is optimized to provide sufficient electrical conductivity enhancement while minimizing the volume occupied by non-lithium material. The flexible thin film structure allows comprehensive surface coverage for conductivity improvement while maintaining high lithium metal oxide content in the core region, achieving both goals through optimized shell thickness control.

Inventive Principle:

Principle #30Flexible shells and thin films

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

This configuration significantly reduces the volume resistance of the cathode, improving both electrical conductivity and structural stability, enabling efficient operation of lithium secondary batteries without the use of conductive materials in the cathode active material layer.

Implementation Method 1

a high specific surface area and a particle aggregation by a van der Waals force may easily occur

Methodology Applied

Scientific EffectVan der Waals force: Van der Waals Force

Implementation Method 2

the core portion may include a nitrogen component doped at a surface of the lithium metal oxide

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS20230335721A1Cathode active material for lithium secondary battery, method of preparing the same and lithium secondary battery including the same

Publication Date: 2023.10.19 SK ON CO LTD

AI summary

A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a core portion containing a lithium metal oxide, and a shell portion covering at least a portion of a surface of the core portion and including a reduced carbon nanotube oxide. The cathode active material provides enhanced electrical conductivity.