Core-Shell Anode Material for Lithium Batteries
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Solution Overview
Problem
Current anode active materials for lithium secondary batteries fail to simultaneously improve electrical characteristics and safety, with existing solutions not adequately maintaining battery performance and safety over repeated charge and discharge cycles.
Innovation Solution
A core-shell anode active material is developed, comprising a carbonaceous material core coated with a shell of spinel-type lithium titanium oxide and metal oxide particles, where the metal oxide fills voids created by the lithium titanium oxide, enhancing conductivity and density, and optionally including thermoplastic polymer and conductive materials for improved coating and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is used as anode active material, then initial discharge capacity is improved, but charge/discharge efficiency and capacity reduce remarkably after repeated cycles
Solution Approach 1:
The invention uses a composite structure combining natural graphite particles with amorphous carbon coating and conductive carbon materials. The amorphous carbon layer protects the graphite crystal structure during cycling while the conductive carbon network maintains electrical conductivity, resolving the contradiction between initial capacity and cycle stability.
Solution Approach 2:
An amorphous carbon thin film is formed on the surface of natural graphite particles. This flexible coating layer accommodates volume changes during charge/discharge cycles, preventing structural degradation and maintaining charge/discharge efficiency while preserving the high capacity of graphite.
2Volume of stationary object
If mesophase graphite is used to improve energy density, then volume energy density is improved, but reversible capacity becomes low
Solution Approach 1:
The invention merges the advantages of mesophase graphite (high density, good electrode formation) with amorphous carbon (high reversible capacity) and conductive carbon materials. The composite structure achieves both high energy density and high reversible capacity by combining materials with complementary properties.
3Quantity of substance
If non-graphitizable carbon is used for safety and high capacity, then safety and capacity are improved, but particle shape and size become irregular after pulverizing
Solution Approach 1:
An amorphous carbon shell is formed on non-graphitizable carbon particles, providing a protective layer that maintains particle integrity and uniformity after pulverizing processes. This shell preserves the safety and capacity advantages while improving particle shape control.
4Reliability
If lithium titanium oxide is used singularly for safety, then safety is improved, but battery characteristics are reduced due to low average voltage
Solution Approach 1:
The invention creates a composite anode material combining lithium titanium oxide (providing safety and structural stability) with carbon materials (providing high capacity and conductivity). This composite structure achieves both safety and excellent battery characteristics by leveraging the complementary properties of each material.
Solution Approach 2:
Different regions of the anode structure have different compositions optimized for different functions: lithium titanium oxide provides safety and structural stability in critical areas, while carbon materials provide high capacity and conductivity in other regions, achieving overall performance optimization.
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, such as charge/discharge efficiency and cycle life, while ensuring safety by reducing reactions with the electrolyte and preventing structural damage, thus providing enhanced battery performance and safety.
Implementation Method 1
a plurality of metal oxide particles, wherein the metal belongs to group 4 or 13 of the periodic table, filling voids formed by the carbonaceous material and the plurality of spinel-type lithium titanium oxide particles
Data Source
AI summary
Provided are an 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 includes a carbonaceous material core; and a shell formed outside of the carbonaceous material core. The shell includes a plurality of spinel-type lithium titanium oxide particles, and a plurality of metal oxide particles, wherein the metal belongs to group 4 or 13 of the periodic table, the metal oxide particles filling voids formed by the carbonaceous material and the plurality of spinel-type lithium titanium oxide particles. The anode active material for a lithium secondary battery has the metal oxide shell, and thus has the improved conductivity, a high output density, and consequently excellent electrical characteristics. The lithium secondary battery manufactured using the anode active material ensures safety sufficiently.