Fluoride-Coated Nickel Cathode for Longer Li-Ion Cycle Life

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Solution Overview

Problem

Existing rechargeable lithium batteries face challenges in achieving high cycle-life characteristics and efficient intercalation/deintercalation of lithium, while also managing residual lithium on the surface, which can lead to safety issues and reduced performance.

Innovation Solution

A positive active material for rechargeable lithium batteries is developed, comprising a nickel-based composite oxide with a nickel content of 60 mol % or higher, coated with a layer of lithium fluoride and metal fluoride produced by firing a metal oxide and a fluorine-based organic material. This coating layer is designed to facilitate lithium intercalation/deintercalation and reduce residual lithium on the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a nickel-based composite oxide with high nickel content (≥60 mol %) is used to achieve high capacity, then the energy density is improved, but residual lithium accumulates on the surface leading to safety issues and reduced cycle-life

Engineering Contradiction:

Improveenergy densityVSAvoidcycle-life characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A coating layer comprising lithium fluoride and metal fluoride is introduced as an intermediary between the nickel-based composite oxide and the electrolyte solution. This coating layer mediates the interaction by preventing direct contact between residual lithium on the oxide surface and the electrolyte, thereby eliminating harmful side reactions while maintaining the high energy density benefits of the nickel-rich composite oxide.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful residual lithium on the surface of the nickel-based composite oxide is converted into beneficial lithium fluoride through reaction with fluorine-containing compounds during the coating process. This transforms the safety hazard into a protective component that forms part of the coating layer, improving both safety and cycle-life characteristics.

Inventive Principle:

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

2Reliability

If a coating layer is applied to remove residual lithium and prevent side reactions, then cycle-life characteristics are improved, but the complexity of the manufacturing process increases

Engineering Contradiction:

Improvecycle-life characteristicsVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating formation process is merged with the existing sintering step by adding a fluorine-containing compound to the sintering atmosphere. This allows the coating layer to form simultaneously with the composite oxide synthesis, eliminating the need for a separate coating step and reducing manufacturing process complexity while still achieving the desired protective coating.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The coating layer forms through a self-service mechanism where the fluorine-containing compound reacts with residual lithium on the oxide surface during the sintering process itself. The system uses its own processing conditions (heat and atmosphere) to create the protective coating without requiring additional external processing steps.

Inventive Principle:

Principle #25Self-service

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 proposed solution enhances the charging/discharging efficiency and cycle-life characteristics of rechargeable lithium batteries by effectively removing residual lithium and preventing side reactions with the electrolyte solution, thereby improving the overall stability and performance of the battery.

Implementation Method 1

a coating layer on the surface of the nickel-based composite oxide, wherein the coating layer is lithium fluoride (LiF) and a metal fluoride produced by firing a metal oxide and a fluorine-based organic material

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Implementation Method 2

metal fluoride produced by firing a metal oxide and a fluorine-based organic material

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 3

capable of facilitating intercalation/deintercalation of lithium during charge and discharge

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Data Source

PatentUS12230787B2Cathode active material for rechargeable lithium battery comprising coating layer comprising lithium fluoride and metal fluoride and method for manufacturing the same

Publication Date: 2025.02.18 SAMSUNG SDI CO LTD

AI summary

Provided is a positive active material for a rechargeable lithium battery including a nickel-based composite oxide having a nickel content of greater than or equal to 60 mol % relative to a total amount of metal excluding lithium and a coating layer on the surface of the nickel-based composite oxide, wherein the coating layer includes lithium fluoride (LiF) and metal fluoride produced by firing a metal oxide and a fluorine-based organic material.