Cathode Active Material Structure for Longer-Life Lithium Batteries

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Solution Overview

Problem

Existing lithium-transition metal composite oxides used in cathodes of lithium secondary batteries face issues with non-uniform chemical structure due to lithium precipitation, leading to reduced life-span and capacity retention, and structural deformation during charging and discharging, which are not adequately addressed by current methods like water washing.

Innovation Solution

Incorporating a lithium-sulfur-containing portion between primary particles of the lithium-transition metal composite oxide, formed through a sulfonyl-based compound aqueous solution without water washing, to stabilize the structure and improve ion conductivity, using a heat treatment process to fix the lithium-sulfur compound.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If water washing is used to remove lithium salt impurities, then impurity removal is attempted, but sufficient removal is not achieved and surface damage is caused

Engineering Contradiction:

Improvelithium salt impurity removalVSAvoidsurface damage

Core Design Contradiction:

Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the washing medium from water to organic solvents (acetonitrile, dimethyl carbonate, ethyl methyl carbonate) with specific dielectric constants and boiling points. This parameter change enables effective lithium salt removal through solubility differences while avoiding the surface damage caused by water, thus resolving the contradiction between impurity removal and surface protection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs disposable organic solvent washing systems that can be easily discarded after use. The solvents are applied to remove impurities and then removed themselves through drying, eliminating the need for complex recovery systems and avoiding cumulative surface damage that might occur with repeated water washing

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Quantity of substance

If lithium-transition metal composite oxide is used as cathode active material, then high energy density is achieved, but non-uniform chemical structure and lithium precipitation occur leading to reduced life-span

Engineering Contradiction:

Improveenergy densityVSAvoidchemical structure uniformity

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality control by using organic solvent washing to specifically target and remove lithium salt precipitates from the surface regions of the composite oxide particles. This localized treatment maintains the high energy density bulk composition while eliminating local non-uniformities that would otherwise degrade performance over time

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent performs preliminary washing treatment with organic solvents before battery assembly to prevent lithium precipitation and chemical structure non-uniformity from developing during storage and initial charging cycles. This preliminary action ensures uniform chemical structure is established before the battery enters service, extending life-span while maintaining high energy density

Inventive Principle:

Principle #10Preliminary action

3Productivity

If conventional manufacturing methods are used, then production efficiency is maintained, but structural deformation occurs during charging and discharging

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidstructural stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent replaces mechanical washing systems with chemical solvent-based cleaning systems. The organic solvents chemically dissolve lithium salt impurities without the mechanical agitation and pressure variations that cause structural deformation. This substitution maintains manufacturing efficiency while preserving the structural integrity of the composite oxide particles during charging and discharging

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method enhances the operational stability and electrochemical properties of the cathode active material, improving initial capacity, life-span, and reducing resistance, thereby stabilizing the battery performance.

Implementation Method 1

a lithium-sulfur-containing portion formed between the primary particles

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

improve ion conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

using a heat treatment process to fix the lithium-sulfur compound

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Data Source

PatentUS12355066B2Cathode active material for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2025.07.08 SK ON CO LTD

AI summary

The cathode active material for a lithium secondary battery according to embodiments of the present invention includes a lithium-transition metal composite oxide particle including a plurality of primary particles, and the lithium-transition metal composite oxide particle includes a lithium-sulfur-containing portion formed between the primary particles. Thereby, it is possible to improve life-span properties and capacity properties by preventing the layer structure deformation of the primary particles and removing residual lithium.