Nitrogen-Doped Graphene Quantum Dot Coating for LTO Anodes

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Solution Overview

Problem

Conventional lithium titanium oxide (LTO) negative electrode materials suffer from low intrinsic electrical conductivity and gas generation issues during charge/discharge cycles, limiting their high-speed charge/discharge performance and stability in lithium-ion batteries.

Innovation Solution

A nitrogen-doped graphene quantum dot coating layer is applied to LTO particles, enhancing their electrical conductivity and preventing gas generation by forming a thin, stable solid-electrolyte interface layer, thereby improving the diffusion coefficient of Li ions and extending battery life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional LTO is used as negative electrode material, then structural stability and safety are improved, but electrical conductivity and rate capability deteriorate

Engineering Contradiction:

Improvestructural stabilityVSAvoidelectrical conductivity

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies composite materials by coating LTO particles with a dual-layer structure consisting of amorphous carbon and TiO2. The amorphous carbon layer provides high electrical conductivity (10^-3 to 10^-1 Scm^-1) while the TiO2 layer maintains structural stability. This composite structure resolves the contradiction between LTO's inherent structural stability and its poor electrical conductivity, achieving both reliability and power performance.

Inventive Principle:

Principle #40Composite materials

2Power

If surface coating with conductive carbon layer is applied to LTO, then electrical conductivity and ion transport are improved, but interfacial reactivity with electrolyte increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidinterfacial reactivity

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite coating structure where amorphous carbon is combined with TiO2. The amorphous carbon provides conductivity while TiO2 acts as a protective barrier with low interfacial reactivity to the electrolyte. This composite approach allows the carbon layer to improve electrical conductivity without exposing reactive carbon surfaces directly to the electrolyte, thus resolving the contradiction between enhanced power performance and reduced harmful interfacial reactions.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The TiO2 layer serves as an intermediary between the amorphous carbon coating and the electrolyte. It mediates the interaction by providing a chemically stable interface that prevents direct contact between reactive carbon and the electrolyte, thereby reducing interfacial reactivity while maintaining the conductivity benefits of the carbon layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If LTO is used for high-speed charge/discharge, then rate capability is improved, but gas generation from SEI layer increases

Engineering Contradiction:

Improvecharge/discharge rateVSAvoidgas generation

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The amorphous carbon-TiO2 composite coating suppresses gas generation during high-speed charge/discharge operations. The TiO2 layer provides chemical stability that prevents electrolyte decomposition and SEI layer formation, while the amorphous carbon ensures rapid electron transport. This composite structure enables high rate capability without the gas generation problems that typically accompany fast charging in conventional LTO systems.

Inventive Principle:

Principle #40Composite materials

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 nitrogen-doped graphene quantum dot coating significantly improves the electrochemical properties of LTO, enabling faster charge transfer, reducing gas generation, and maintaining battery capacity for 500 or more cycles without disruption, while protecting the electrode from electrolyte reactions.

Implementation Method 1

enhancing their electrical conductivity

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

forming a thin, stable solid-electrolyte interface layer

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 3

improving the diffusion coefficient of Li ions

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11495795B2LTO negative electrode material, having graphene quantum dot doped with nitrogen attached thereto, with excellent rate characteristics and no gas generation during long term charge and discharge

Publication Date: 2022.11.08 DAEGU GYEONGBUK INSTITUTE OF SCIENCE AND TECHNOLOGY

AI summary

One example of the present invention provides a negative electrode material. Such a negative electrode material may comprise lithium titanium oxide-based particles and a graphene quantum dot coating layer doped with nitrogen that is positioned on the lithium titanium oxide-based particles.