Catalyst-Dispersed Pitch Powders for Lower-Temperature Graphitization
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Solution Overview
Problem
Existing synthetic graphite production processes are energy-intensive and costly, and graphite anodes for lithium-ion batteries face challenges with high production costs, limited capacity, fast charging, and cycle life due to surface graphitization catalysts leading to insulative carbides and nitrides.
Innovation Solution
Incorporating a graphitization catalyst within the interior of a graphite precursor, dispersed in petroleum pitch, to facilitate graphitization at lower temperatures and reduce production time, using mechanisms like diffusion, intercalation, and carbide formation-decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If surface graphitization catalysts are used to promote graphitization, then graphitization rate is improved, but insulative carbides and nitrides form on the surface increasing contact resistance
Solution Approach 1:
The patent uses an organic precursor as an intermediary carrier to deliver the graphitization catalyst to the graphite precursor surface. The organic precursor decomposes during heat treatment to leave behind the catalyst, avoiding direct contact between the catalyst and the graphite surface that would form insulative carbides and nitrides. This intermediary approach enables catalytic graphitization without the harmful surface reactions.
Solution Approach 2:
The organic precursor acts as a temporary, consumable carrier that is deliberately designed to decompose during the heat treatment process. This disposable intermediary fulfills its function of delivering the catalyst and then is discarded through decomposition, leaving no harmful residues on the graphite surface.
2Manufacturing precision
If high temperatures (2800-3400°C) and extended reaction times are used to achieve high conversion of amorphous carbon to graphite, then conversion percentage is improved, but energy consumption increases significantly
Solution Approach 1:
The patent changes the chemical parameters of the system by introducing a graphitization catalyst through organic precursor decomposition. This chemical modification enables the graphitization process to proceed at lower temperatures (reducing thermal energy input) and shorter times while achieving the same or higher conversion percentages of amorphous carbon to graphite.
Solution Approach 2:
The organic precursor is pre-loaded with the graphitization catalyst before the heat treatment process. This preliminary preparation ensures that the catalyst is already in position and ready to act immediately when heating begins, eliminating the need for high temperatures and extended times to achieve effective catalyst distribution and graphitization.
3Temperature
If graphitization catalyst is applied on the surface of graphite precursor, then graphitization temperature is reduced, but the catalyst reacts with carbon surface forming insulative carbides or nitrides
Solution Approach 1:
The organic precursor serves as a mediator that delivers the graphitization catalyst to the graphite precursor surface indirectly. During heat treatment, the organic precursor decomposes first, releasing the catalyst in a controlled manner that prevents direct reaction between the catalyst and carbon surface, thus avoiding insulative carbide or nitride formation while still achieving temperature reduction.
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 method achieves high discharge capacity, low capacity loss, and improved cycle life for lithium-ion battery anodes by reducing graphitization temperatures and time, while minimizing energy consumption and contact resistance.
Implementation Method 1
using mechanisms like diffusion, intercalation, and carbide formation-decomposition
Implementation Method 2
using mechanisms like diffusion, intercalation, and carbide formation-decomposition
Implementation Method 3
the large aromatic molecules in coke and petroleum pitches may first be converted to amorphous carbon in a carbonization process taking place at a temperature of about 700° C. to about 1800° C., followed by subsequent conversion of the amorphous carbon to graphite in a graphitization process
Data Source
AI summary
Composite powders for electrode production may be formed by blending a graphitization catalyst or precursor thereof with petroleum pitch under grinding conditions. The composite powders may comprise about 0.1 wt. % to about 30 wt. % graphitization catalyst or a precursor thereof, based on total mass of the composite powder, and about 20 wt. % to about 99.9 wt. % petroleum pitch, based on total mass of the composite powder. The graphitization catalyst or the precursor thereof is dispersed in a matrix comprising the petroleum pitch, and the petroleum pitch comprises a plurality of pitch particles. The composite powders may be subsequently carbonized and then graphitized under conditions that may be less severe than un-catalyzed graphitization. The grinding conditions for forming the composite powders may include melt blending to form a continuous pitch matrix, wherein at least a portion of the graphitization catalyst or the precursor thereof may be dispersed within an interior of the pitch particles.