Linked Stacks of Partly Reduced Graphene via Ester Bonding
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Solution Overview
Problem
Graphene is prone to rebonding due to Van der Waals forces, leading to a loss of high electrical conductivity and stability, especially when produced from graphite, and existing methods fail to maintain a graphene laminated structure with sufficient electrical conductivity for practical applications, particularly in capacitors.
Innovation Solution
The production of linked stacks of partly reduced graphene using ester-bonding between carboxyl and hydroxyl groups of graphene oxide, with a nanosubstance like a carbon nanotube as a spacer, to maintain high electrical conductivity and stability, allowing for a three-dimensional stacked structure that prevents rebonding and enhances dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If graphene is produced from graphite through oxidation and reduction, then mass production at low cost is achieved, but graphene sheets are easily rebonded by Van der Waals force to reproduce graphite, losing electrical conductivity
Solution Approach 1:
A nanosubstance is introduced as an intermediary material between graphene sheets to prevent direct contact and Van der Waals bonding. The nanosubstance acts as a spacer that maintains separation while allowing the graphene structure to be produced through conventional oxidation-reduction processes, thus preserving electrical conductivity during mass production
Solution Approach 2:
The invention creates a composite structure combining graphene sheets with nanosubstance spacers. This composite material integrates the excellent electrical conductivity of graphene with the structural stability provided by the nanosubstance, preventing rebonding while maintaining the desired electrical properties for practical applications
2Stability of the object's composition
If graphene sheets are laminated to increase thickness, then structural stability is improved, but most surfaces contact each other causing loss of conductive properties
Solution Approach 1:
The nanosubstance serves as a mediator between laminated graphene sheets, enabling structural stability through controlled spacing rather than direct surface contact. This intermediary layer prevents the loss of conductive properties that would otherwise occur when sheets are simply stacked together
Solution Approach 2:
Instead of increasing thickness through simple stacking in one dimension, the invention introduces spacing in the vertical dimension using nanosubstance spacers. This creates a three-dimensional laminated structure where sheets are separated at multiple points, maintaining surface area and conductivity while achieving structural stability
3Reliability
If graphene is reduced completely to remove oxygen groups, then electrical conductivity is maximized, but dispersibility in solvent is lost and aggregation occurs
Solution Approach 1:
The nanosubstance acts as an intermediary that enables dispersibility without requiring oxygen-containing groups on the graphene surface. By providing steric hindrance and preventing aggregation, the nanosubstance allows completely reduced graphene to maintain both high conductivity and good dispersibility in solvents
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
This method maintains high electrical conductivity and stability of graphene, enabling the production of graphene electrode films with large power and energy density, suitable for high-performance capacitors, and reduces production costs by simplifying the process.
Implementation Method 1
graphene is so unstable by reason of a thickness of a carbon atom that produced graphenes are easily rebonded by Van der Waals force in contacting with each other to reproduce graphite
Implementation Method 2
stacks of partly reduced graphene obtained by multilayering partly reduced graphene while using a nanosubstance as a spacer and a conjugative agent are three-dimensionally linked by ester-bonding chemically functionalized molecules of a graphene outer edge to each other
Data Source
AI summary
The object of the present invention is to provide linked stacks of reduced graphene, in which excellent electrical property on the surface of graphene may be utilized, a method for producing the same, powder comprising the same, and film comprising the same. The object may be solved by using linked stacks of partly reduced graphene 11 comprising two or more stacks of partly reduced graphene 21 to 24 linked together, in which the stack of partly reduced graphene 21 has two or more sheets of partly reduced graphene 31 and a nanosubstance 32 held between the sheets of partly reduced graphene 31, the partly reduced graphene 31 has no carbonyl groups and has carboxyl groups 31a and hydroxyl groups 31b, and different stacks of partly reduced graphene 21 to 24 are linked to each other by an ester bond 34.