Silicon-Based Alloy Core with Amorphous Carbon and Lithium Titanium Oxide Shell

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Solution Overview

Problem

Lithium-ion batteries using silicon-based negative active materials face issues with volumetric expansion and side reactions with the electrolyte, leading to degraded rate capability and lifespan due to the formation of a solid electrolyte interface layer and broken conduction paths.

Innovation Solution

A composite electrode active material is developed with a core portion of silicon-based alloy and a shell portion coated with an amorphous carbon material and lithium titanium oxide, which suppresses volumetric expansion and side reactions, maintaining electrical conductivity and improving battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-based alloy is used as negative active material, then capacity is improved, but volumetric expansion and side reactions occur leading to degraded rate capability and lifespan

Engineering Contradiction:

ImprovecapacityVSAvoidrate capability and lifespan

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies composite materials by combining silicon-based alloy core with a shell portion containing amorphous carbon material and lithium titanium oxide. This composite structure allows the silicon core to provide high capacity while the shell provides structural stability, prevents volumetric expansion, and suppresses side reactions with electrolyte, thereby resolving the contradiction between capacity improvement and reliability maintenance

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent uses a shell portion composed of amorphous carbon material and lithium titanium oxide that acts as a flexible protective layer. This shell accommodates the volumetric expansion of silicon during lithium insertion while maintaining structural integrity, preventing particle disintegration and contact loss, thus preserving rate capability and lifespan

Inventive Principle:

Principle #30Flexible shells and thin films

2Quantity of substance

If silicon-based alloy is used as negative active material, then capacity is improved, but SEI layer formation and broken conduction paths occur

Engineering Contradiction:

ImprovecapacityVSAvoidSEI layer formation and broken conduction paths

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces amorphous carbon material and lithium titanium oxide as intermediary substances between the silicon-based alloy and the electrolyte. The amorphous carbon layer serves as a conductive intermediary that prevents direct contact between silicon and electrolyte, suppressing SEI layer formation while maintaining electrical conductivity. The lithium titanium oxide acts as a structural intermediary that prevents conduction path breakage during volume changes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The shell portion formed by amorphous carbon material provides a flexible conductive coating that maintains electrical contact during silicon's volumetric changes. This thin film structure prevents conduction path breakage while allowing the necessary volume expansion, thus eliminating the harmful effect of broken conduction paths

Inventive Principle:

Principle #30Flexible shells and thin films

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 composite electrode active material enhances the rate characteristics and lifespan of lithium-ion batteries by preventing SEI layer formation and maintaining electrical conductivity, resulting in improved capacity retention and charging efficiency.

Implementation Method 1

a shell portion disposed on the core portion and including a coating layer, wherein the coating layer includes an amorphous carbon material and a lithium titanium oxide

Methodology Applied

Scientific EffectVolumetric expansion suppression:

Implementation Method 2

the coating layer includes an amorphous carbon material and a lithium titanium oxide

Methodology Applied

Scientific EffectSide reaction suppression:

Implementation Method 3

maintaining electrical conductivity and improving battery performance

Methodology Applied

Scientific EffectElectrical conductivity maintenance:

Data Source

PatentUS10535871B2Composite electrode active material, lithium battery including the same, and preparation method thereof

Publication Date: 2020.01.14 SAMSUNG SDI CO LTD

AI summary

A composite electrode active material includes: a core portion including a silicon-based alloy; and a shell portion disposed on the core portion and including a coating layer, wherein the coating layer includes an amorphous carbon material and a lithium titanium oxide. A lithium battery including the composite electrode active material and a method of manufacturing the composite electrode active material are also provided.