Li-doped SiOx Negative Electrode for Lithium Battery

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Solution Overview

Problem

Si-based negative active materials in rechargeable lithium batteries exhibit lower initial efficiency and shorter cycle life due to irreversible reactions and volume changes, leading to SEI film damage and electrolyte leakage.

Innovation Solution

A negative electrode active material layer composition comprising Li-doped SiOx, an aqueous binder, and water, with optional Li2CO3 and carbon-based materials, is developed, where Li-doping and carbon coating enhance conductivity and suppress volume expansion, and the SEI protection film formed by Li2CO3 improves initial efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If Si-based negative active material is used, then capacity is improved, but initial efficiency deteriorates due to irreversible reactions

Engineering Contradiction:

ImprovecapacityVSAvoidinitial efficiency

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies parameter changes by doping Li into SiOx at specific ratios (0.5-1.9 moles Li per mole SiOx) to modify the material's electrochemical properties. This doping changes the stoichiometry and electronic structure of SiOx, reducing irreversible reactions and improving initial efficiency while maintaining high capacity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining Li-doped SiOx with carbon-based materials (natural graphite, artificial graphite, hard carbon, or soft carbon). This composite structure leverages the high capacity of Si-based materials while the carbon component provides structural stability and reduces irreversibility, achieving both high capacity and good initial efficiency

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Si-based negative active material is used, then capacity is improved, but cycle life deteriorates due to volume expansion

Engineering Contradiction:

ImprovecapacityVSAvoidcycle life

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The patent changes the physical and chemical parameters of SiOx through Li doping, which modifies the material's volume expansion characteristics. The Li doping alters the crystal structure and bonding, reducing the magnitude of volume changes during lithium insertion/extraction cycles, thereby improving cycle life

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite structure of Li-doped SiOx with carbon-based materials provides a solution where the carbon matrix accommodates volume expansion of the Si-based active material. This composite approach maintains structural integrity over multiple cycles, enabling both high capacity and long cycle life

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If Si-based negative active material is used, then capacity is improved, but SEI film stability deteriorates due to swelling

Engineering Contradiction:

ImprovecapacityVSAvoidSEI film stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent changes the surface properties and volume stability of SiOx through Li doping, which reduces the mechanical stress and swelling that damage the SEI film. The doped material exhibits more stable volume changes, protecting the SEI film from repeated damage and improving overall battery stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The carbon-based composite material provides a protective matrix that stabilizes the SEI film formation. The carbon component facilitates uniform lithium distribution and reduces localized swelling, thereby protecting the SEI film from damage while maintaining high capacity

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 composition achieves higher initial efficiency and extended cycle life by reducing irreversibility and mechanical stress, maintaining battery performance through improved SEI protection and conductivity.

Implementation Method 1

Li-doping and carbon coating enhance conductivity and suppress volume expansion

Methodology Applied

Scientific EffectVolume expansion suppression:

Implementation Method 2

Li-doping and carbon coating enhance conductivity

Methodology Applied

Scientific EffectConductivity enhancement:

Implementation Method 3

the SEI protection film formed by Li2CO3 improves initial efficiency

Methodology Applied

Scientific EffectSEI film formation:

Data Source

PatentUS9799877B2Negative electrode active material layer composition for rechargeable lithium battery and method of preparing and using the same

Publication Date: 2017.10.24 SAMSUNG SDI CO LTD

AI summary

A negative electrode active material layer composition for a rechargeable lithium battery is disclosed. The negative electrode active material layer composition includes a negative active material including Li-doped SiOx (0<x<2), an aqueous binder, and pure water. In addition, a method of manufacturing the negative electrode active material layer composition, and a negative electrode and a rechargeable lithium battery including the same are also disclosed.