Sulfur-Modified Cathode Active Material for Longer-Cycle Li Batteries

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Solution Overview

Problem

Lithium secondary batteries face issues with degraded output characteristics and cycle life due to side reactions between the cathode active material and electrolyte, necessitating improved materials and manufacturing processes.

Innovation Solution

A cathode active material comprising lithium-transition metal oxide particles with a lithium-sulfur-metal-containing portion, controlled particle size and uniform sulfur distribution, achieved through a specific preparation method involving dry mixing, solvent addition, drying, and calcination, reduces impurities and enhances structural stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cathode active materials are used, then the battery can operate, but side reactions between the cathode active material and electrolyte occur, leading to degraded output characteristics and cycle life

Engineering Contradiction:

Improvecycle lifeVSAvoidside reactions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A lithium-sulfur-metal-containing portion is introduced as an intermediary layer between the cathode active material particles and the electrolyte. This intermediary portion prevents direct contact and side reactions between the cathode material and electrolyte, thereby improving cycle life and output characteristics while maintaining battery operation

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cathode active material is designed as a composite structure consisting of lithium-transition metal oxide particles combined with lithium-sulfur-metal-containing portions. This composite material approach provides both the electrochemical activity of the transition metal oxide and the protective/functional properties of the lithium-sulfur-metal component, resolving the contradiction between reactivity and stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If the cathode active material is designed to improve output characteristics and cycle life, then performance is enhanced, but the manufacturing process becomes more complex with multiple steps including dry mixing, solvent addition, drying, and calcination

Engineering Contradiction:

Improveoutput characteristicsVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The lithium-sulfur-metal-containing portions are formed in advance during the manufacturing process through controlled dry mixing, solvent addition, and drying steps that create preliminary structures before final calcination. This preliminary action allows the complex structure to be built systematically, improving output characteristics while managing manufacturing complexity through staged processing

Inventive Principle:

Principle #10Preliminary action

3Duration of action of stationary object

If uniform sulfur distribution is achieved in the lithium-transition metal oxide particles, then cycle life and high-temperature storage characteristics are improved, but the manufacturing precision requirements increase with controlled particle size and uniform distribution

Engineering Contradiction:

Improvehigh-temperature storage characteristicsVSAvoidsulfur distribution uniformity

Core Design Contradiction:

Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The sulfur is not uniformly distributed throughout the entire cathode structure, but is specifically localized in the lithium-sulfur-metal-containing portions that are positioned between particles or on surfaces. This local quality approach achieves the benefit of improved high-temperature storage characteristics through targeted sulfur placement while managing manufacturing precision requirements by concentrating the uniformity requirement to specific regions rather than the entire structure

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 solution improves the capacity, cycle life, and high-temperature storage characteristics of lithium secondary batteries by minimizing side reactions and reducing gas generation, thereby enhancing overall performance.

Implementation Method 1

lithium-sulfur-metal-containing portion

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

X-ray photoelectron spectroscopy (XPS) analysis

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS20250346499A1Cathode active material for lithium secondary battery, method of preparing the same and lithium secondary battery including the same

Publication Date: 2025.11.13 SK ON CO LTD

AI summary

A cathode active material for a lithium secondary battery according to embodiments of the present disclosure comprises a lithium-sulfur-metal-containing portion and lithium-transition metal oxide particles having a minimum particle diameter (Dmin) of greater than 1 μm, wherein a relative standard deviation of the sulfur signal values of the lithium-transition metal oxide particles, as measured repeatedly ten times by X-ray photoelectron spectroscopy (XPS) analysis, is 10.5% or less.