Fluorinated Nickel-Rich Cathode Material for Stable Cycle Life

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Solution Overview

Problem

Existing lithium secondary batteries face challenges with nickel-rich positive electrode active materials that experience side reactions with the electrolyte, leading to capacity degradation and reduced cycle life due to structural instability during long-term cycling.

Innovation Solution

A fluorine-containing positive electrode active material with a layered structure is developed, featuring a controlled nickel oxidation state and a fluorine-induced grain coating layer, which suppresses side reactions and maintains structural stability through a long-range ordered lattice and fluorine-containing grain coating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If nickel content is increased to achieve high capacity, then discharge capacity is improved, but structural stability deteriorates leading to capacity degradation and reduced cycle life

Engineering Contradiction:

Improvedischarge capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by controlling the oxidation state of nickel (Ni3+ and Ni2+) and adjusting the fluorine content in the positive electrode active material. This modifies the electronic and structural parameters of the material to achieve both high capacity and improved structural stability, resolving the contradiction between nickel content increase and structural degradation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by incorporating fluorine into the nickel-rich layered structure. The fluorine-containing positive electrode active material creates a composite system where fluorine modifies the crystal structure and forms a protective grain coating layer, enabling high nickel content while maintaining structural integrity and preventing capacity degradation.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If nickel-rich composition is used to enhance capacity, then energy density is improved, but cycle life is reduced due to side reactions with electrolyte

Engineering Contradiction:

Improveenergy densityVSAvoidcycle life

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The patent introduces fluorine as an intermediary element that mediates between the nickel-rich active material and the electrolyte. Fluorine forms a protective grain coating layer that acts as a barrier, preventing direct contact and side reactions between the nickel-rich material and electrolyte, thereby extending cycle life while maintaining high energy density.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potential harm of nickel-rich materials (which are prone to side reactions) into a benefit by using fluorine to create a stable, protective surface layer. This fluorine-containing coating transforms the reactive nickel-rich surface into a stable interface that resists electrolyte decomposition, turning a liability into an asset for long-term cycling stability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If fluorine content is increased to improve cycle characteristics, then structural stability is enhanced, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural stabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent applies local quality by concentrating fluorine at specific locations - forming a grain coating layer on the surface and incorporating it into the layered structure where it is most needed for stability. This localized fluorine distribution achieves maximum structural stabilization benefit while minimizing the overall fluorine content required, thereby reducing manufacturing complexity compared to uniform fluorine distribution.

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 fluorine-containing material enhances cycle life and capacity retention by preventing electrolyte penetration and structural degradation, maintaining high discharge capacity even after thousands of cycles.

Implementation Method 1

fluorine-induced grain coating layer, which suppresses side reactions and maintains structural stability

Methodology Applied

Scientific EffectGrain coating: Coatings

Implementation Method 2

maintains structural stability through a long-range ordered lattice and fluorine-containing grain coating

Methodology Applied

Scientific EffectOrdered lattice structure: Crystallisation

Data Source

PatentUS12586791B2Fluorine-containing positive electrode active material for lithium secondary battery, and lithium secondary battery including same

Publication Date: 2026.03.24 INDUSTRY UNIVERSITY COOPERATION FOUNDATION HANYANG UNIVERSITY

AI summary

The present invention pertains to a positive electrode active material for a lithium secondary battery, the positive electrode active material having a layered structure and containing lithium, transition metals, fluorine (F), and oxygen, wherein the layered structure includes a lithium layer consisting solely of lithium and a transition metal layer consisting solely of transition metals including nickel, the nickel includes Ni3+ and Ni2+ in terms of oxidation number, and the ratio (Ni2+/Ni3+) of Ni2+ to Ni3+ increases as the fluorine content increases.