Composite Cathode Coating for High-Voltage Lithium Battery Stability

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Solution Overview

Problem

Lithium batteries face challenges in maintaining structural stability and cycle characteristics during high-voltage charging, leading to deteriorated capacity and rate capabilities due to side reactions between the electrolyte and cathode active materials.

Innovation Solution

A composite cathode active material is developed, featuring a lithium composite oxide with a coating layer comprising metal oxide and lithium fluoride, which minimizes direct contact with the electrolyte, suppressing side reactions and enhancing structural stability, and includes a spinel phase for improved electrical conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a lithium battery uses high-voltage charging to increase capacity and voltage, then the energy density and power output improve, but the structural stability of the cathode active material deteriorates due to side reactions with the electrolyte

Engineering Contradiction:

Improveenergy densityVSAvoidstructural stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by creating a core-shell structure where the cathode active material core is coated with a protective layer containing metal fluoride and metal oxide. This composite structure allows the inner core to provide high-voltage charging capability for increased energy density, while the outer protective layer prevents direct contact between the electrolyte and cathode material, thereby maintaining structural stability during high-voltage operation

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent uses an intermediary approach by introducing a protective coating layer as a mediator between the electrolyte and the cathode active material. This intermediate layer contains metal fluoride and metal oxide compounds that act as a barrier, preventing harmful side reactions while allowing ionic transport, thus enabling high-voltage charging without compromising structural stability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Duration of action of moving object

If the cathode active material undergoes repeated charging and discharging, then the battery capacity increases over time through utilization, but the rate capability deteriorates due to structural changes and side reactions

Engineering Contradiction:

Improvecycle lifeVSAvoidrate capability

Core Design Contradiction:

Duration of action of moving objectVSSpeed

Solution Approach 1:

The composite core-shell structure with protective coating enables the cathode material to withstand repeated charging/discharging cycles by preventing structural degradation. The protective layer maintains structural integrity over time, allowing sustained capacity utilization while preserving rate capability for high-speed charging and discharging operations

Inventive Principle:

Principle #40Composite materials

3Productivity

If the cathode active material directly contacts the electrolyte, then the electrochemical reactions proceed efficiently, but side reactions occur leading to capacity loss and reduced lifespan

Engineering Contradiction:

Improveelectrochemical efficiencyVSAvoidlifespan

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The protective coating layer serves as an intermediary that maintains efficient electrochemical reactions by allowing ionic transport while blocking harmful direct contact between the electrolyte and cathode active material. This mediator prevents side reactions that would otherwise lead to capacity loss and reduced battery lifespan

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a thin film protective coating that acts as a flexible barrier between the electrolyte and cathode material. This thin film structure maintains ionic conductivity for efficient electrochemical reactions while providing sufficient protection against side reactions, thereby extending battery lifespan without compromising productivity

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

The composite cathode active material improves high-rate characteristics, capacity retention, and lifespan of lithium batteries by reducing structural changes and side reactions, while maintaining excellent electrochemical performance.

Implementation Method 1

a coating layer including a metal oxide and a lithium fluoride, wherein the coating layer is disposed on at least a portion of a surface of the lithium composite oxide

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

includes a spinel phase for improved electrical conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11011746B2Composite cathode active material for lithium battery, cathode for lithium battery including the same, and lithium battery including the cathode

Publication Date: 2021.05.18 SAMSUNG ELECTRONICS CO LTD

AI summary

A composite cathode active material for a lithium battery including: a lithium composite oxide; and a coating layer including a metal oxide and a lithium fluoride, (LiF) wherein the coating layer is disposed on at least a portion of a surface of the lithium composite oxide.