Lithium Anode Metal Nitride Coating Volume Expansion
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Solution Overview
Problem
Current anode active materials for lithium rechargeable batteries, such as carbonaceous and metal-based materials, face limitations in capacity and cycle characteristics, leading to poor performance in high-capacity batteries due to issues like dendrite formation and irreversible lithium intercalation.
Innovation Solution
An anode active material comprising a base material alloyable with lithium coated with a metal nitride, prepared by contacting the base material with a metal oxide precursor and heat-treating it in a nitrogen or ammonia atmosphere, enhances initial efficiency and lifespan by mitigating volume changes during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal-based anode active materials are used to increase lithium intercalation capacity, then capacity is improved, but cycle characteristics deteriorate due to poor structural stability
Solution Approach 1:
The patent applies composite materials by combining a base material (metal or intermetallic compound) with a carbon coating layer. This composite structure allows the metal core to provide high lithium intercalation capacity while the carbon coating provides structural stability and conductivity, resolving the contradiction between capacity and cycle characteristics.
Solution Approach 2:
The patent uses a thin carbon coating film on the metal base material. This flexible shell accommodates volume changes during lithium intercalation and deintercalation, preventing structural degradation and maintaining cycle characteristics while allowing the metal core to achieve high capacity.
2Quantity of substance
If amorphous carbon is used as anode active material to achieve high capacity, then capacity is improved, but lithium intercalation becomes highly irreversible
Solution Approach 1:
The patent changes the structural parameters of the carbon material by using crystalline carbon structures (graphite, carbon nanotubes, fullerenes) instead of amorphous carbon. This parameter change maintains high capacity while significantly improving the reversibility of lithium intercalation due to the ordered structure facilitating lithium insertion and extraction.
3Quantity of substance
If crystalline carbon is used as anode active material to achieve high theoretical capacity, then capacity is improved, but practical limitations reduce the actual capacity
Solution Approach 1:
The patent creates a composite structure where metal or intermetallic compound particles are embedded in a carbon matrix. This composite approach allows the metal component to provide high theoretical capacity through alloying reactions while the carbon matrix provides practical benefits including conductivity, structural integrity, and accessible lithium insertion sites, thereby achieving both high theoretical and practical capacity.
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 anode active material with a metal nitride coating exhibits improved initial efficiency and extended lifespan by preventing electrical isolation and maintaining conductivity, outperforming traditional materials in cycle characteristics and capacity retention.
Implementation Method 1
a metal nitride disposed on the base material... mitigating volume changes during charging and discharging
Implementation Method 2
heat treating the mixture in an atmosphere including at least one selected from nitrogen and ammonia to prepare the anode active material
Data Source
AI summary
An anode active material for a lithium rechargeable battery, the anode active material including: a base material which is alloyable with lithium and a metal nitride disposed on the base material.