Core-Shell Anode Material for Lithium Battery Cycle Stability

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Solution Overview

Problem

Current anode active materials for lithium secondary batteries face challenges in maintaining excellent electrical characteristics and safety, with existing solutions failing to adequately address the reduction in charge/discharge efficiency and capacity over cycles, and safety concerns.

Innovation Solution

A core-shell anode active material is developed, comprising a carbon-based material core coated with a spinel-type lithium titanium oxide shell, enhancing conductivity and safety by preventing electrolyte decomposition and reducing surface reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If natural graphite is used as anode active material, then low price and excellent initial discharge capacity are achieved, but charge/discharge efficiency and capacity reduce remarkably during cycles

Engineering Contradiction:

Improveinitial discharge capacityVSAvoidcharge/discharge efficiency stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies composite materials by combining natural graphite core with a shell structure consisting of carbonaceous material and metal oxide. This composite structure maintains the high capacity of natural graphite while the shell prevents degradation during cycling, resolving the contradiction between initial capacity and cycle stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent uses a shell structure comprising carbonaceous material and metal oxide that flexibly accommodates volume changes of the graphite core during lithium insertion/extraction. This shell protects the graphite from electrolyte decomposition and maintains structural integrity over cycles, addressing the reliability issue.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If lithium titanium oxide is used as anode active material, then safety and durability are improved, but average voltage is low reducing battery characteristics

Engineering Contradiction:

Improvesafety and durabilityVSAvoidaverage voltage

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies local quality by placing metal oxide (such as lithium titanium oxide) specifically in the shell portion rather than throughout the entire anode. This localized application provides safety and durability benefits where needed (at the surface interface with electrolyte) while the graphite core maintains high voltage characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The composite structure combines the safety benefits of lithium titanium oxide in the shell with the high voltage characteristics of graphite in the core, achieving both reliability improvement and power maintenance through material composition optimization.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If non-graphitizable carbon is used to achieve large capacity, then safety is improved, but particle size is small with micropores causing low density and irregular shape after pulverizing

Engineering Contradiction:

ImprovecapacityVSAvoidparticle shape and size uniformity

Core Design Contradiction:

Quantity of substanceVSShape

Solution Approach 1:

The patent merges the advantages of different materials by combining natural graphite (which provides good particle shape and density) with non-graphitizable carbon or metal oxide components in the shell structure. This combination achieves large capacity and safety benefits while maintaining uniform particle morphology.

Inventive Principle:

Principle #5Merging (Combining)

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 core-shell structure improves electrical characteristics, specifically high-rate and low-temperature discharge performance, while ensuring safety through reduced heat generation and surface film conductivity, maintaining battery performance and safety over cycles.

Implementation Method 1

The lithium titanium oxide is an anode active material having a spinel-type stable structure

Methodology Applied

Scientific EffectSpinel structure stability:

Implementation Method 2

ensuring safety through reduced heat generation and surface film conductivity

Methodology Applied

Scientific EffectSurface film formation:

Implementation Method 3

enhancing conductivity and safety by preventing electrolyte decomposition and reducing surface reactions

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

comprising a carbon-based material core coated with a spinel-type lithium titanium oxide shell

Methodology Applied

Scientific EffectCoating/Deposition: Deposition (physical)

Data Source

PatentUS9647262B2Core-shell type anode active material for lithium secondary battery, method for preparing the same and lithium secondary battery comprising the same

Publication Date: 2017.05.09 SOLAREDGE TECH KOREA LTD CO

AI summary

The present invention relates to a core-shell type anode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery comprising the same. The anode active material for a lithium secondary battery according to the present invention comprises a carbon based material core portion; and a shell portion formed outside of the carbon based material core portion by coating the carbon based material core portion with a spinel-type lithium titanium oxide. The anode active material for a lithium secondary battery according to the present invention has the metal oxide shell portion, and thus has the improved conductivity, a high output density, and consequently excellent electrical characteristics.