Fluorinated Spinel Cathode for High-Voltage Stability

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Solution Overview

Problem

Lithium batteries with cathodes having a spinel structure face issues with side reactions at high voltages and transition metal release at high temperatures, leading to decreased charge and discharge efficiency and lifetime characteristics.

Innovation Solution

A cathode with a lithium transition metal oxide having a spinel structure, a conductive agent, and a binder, where at least a portion of the surface is fluorinated to form a protective layer that prevents side reactions with the electrolyte and transition metal release.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a spinel structure cathode active material is used at high voltage (4.6 V or greater), then high energy density is achieved, but side reaction with electrolyte occurs leading to decreased charge and discharge efficiency and lifetime characteristics

Engineering Contradiction:

Improveenergy densityVSAvoidcharge and discharge efficiency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A fluorinated protective layer is introduced as an intermediary between the spinel structure cathode active material and the electrolyte. This layer prevents direct contact and side reactions while allowing lithium ion transport, thereby maintaining high energy density operation at 4.6V or greater while improving charge and discharge efficiency and lifetime characteristics

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The surface chemistry of the cathode active material is modified by fluorination, changing the chemical composition and properties of the surface layer. This parameter change creates a protective interface that suppresses side reactions with the electrolyte, enabling stable high-voltage operation without sacrificing energy density

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If a spinel structure cathode active material is used at high temperatures, then high energy density is achieved, but transition metal release occurs leading to low charge and discharge efficiency and poor high-temperature lifetime characteristics

Engineering Contradiction:

Improveenergy densityVSAvoidhigh-temperature lifetime characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The fluorinated protective layer serves as a thermal barrier and chemical stabilizer between the spinel structure cathode material and the environment at high temperatures. This intermediary layer prevents transition metal release while maintaining structural integrity, thereby improving charge and discharge efficiency and high-temperature lifetime characteristics without compromising energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a fluorinated protective layer is applied to the cathode active material layer, then side reaction with electrolyte and transition metal release are suppressed, but device complexity increases

Engineering Contradiction:

Improvelifetime characteristicsVSAvoidcathode structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fluorinated protective layer is formed in advance during the cathode manufacturing process, before the cathode is assembled into the battery. This preliminary action integrates the protective function into the existing manufacturing workflow without requiring additional complex steps, thereby improving lifetime characteristics while minimizing increases in device complexity

Inventive Principle:

Principle #10Preliminary action

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 fluorinated cathode improves charge and discharge efficiency and lifetime characteristics of lithium batteries at both room and high temperatures, making them suitable for high-performance devices and electric vehicles.

Implementation Method 1

at least a portion of a surface of the cathode active material layer is fluorinated

Methodology Applied

Scientific EffectFluorination:

Implementation Method 2

a fluorinated protective layer may prevent a side reaction with an electrolyte. Also, the fluorinated protective layer may prevent release of a transition metal

Methodology Applied

Scientific EffectChemical bonding: Chemical Bonding

Data Source

PatentUS9070931B2Cathode, method of preparing the same, and lithium battery including the cathode

Publication Date: 2015.06.30 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY

AI summary

A cathode, a method of forming the cathode and a lithium battery including the cathode. The cathode includes a current collector and a cathode active material layer disposed on the current collector; the cathode active material layer includes a lithium transition metal oxide having a spinel structure, a conductive agent, and a binder; and at least a portion of a surface of the cathode active material layer is fluorinated.