1. What graphene is (the short version)

Graphene is a one-atom-thick sheet of carbon atoms arranged in a hexagonal (honeycomb) lattice. In 2004 Novoselov and co-workers reported films a few atomic layers thick, peeled from graphite, with a room-temperature mobility of about 10,000 cm²/V·s and electric-field-induced electrons and holes Sourced [Ref. 1].

• The numbers are high: the strength of a free-standing monolayer, the thermal conductivity of a suspended monolayer and the mobility of a suspended device have all been reported far above those of most materials Sourced (Chapter 2, with measurement method and sample for each).
• The route changes the material: peeling graphite, growing on copper, oxidising then reducing, or building directly from a carbon source all give different layer counts, defects, oxygen, impurities and flake sizes (Chapters 3 to 5).
• Market labels are not uniform: a 2018 survey of samples from 60 producers reported that overall quality was rather poor and that many were graphite microplatelets Sourced [Ref. 2] (Chapter 6).

2. Structure and properties — the sample state behind each number

Below, representative graphene properties are listed together with what was measured. All come from small, low-defect monolayer pieces, and none translates directly into the performance of a powder or a film.

All Sourced (as stated in each paper's abstract). Conditions differ, so this table does not rank the rows.

Converting strength to three dimensions depends on an assumption

Lee et al. obtained their values first as in-plane force per unit width (N/m), and converted them to bulk graphite afterwards Sourced [Ref. 3]. A monolayer has no well-defined thickness, so a figure in GPa depends on the thickness assigned to a layer. Here is a check Our calculation.

3. Five production routes and what each delivers

Graphene production divides broadly into thinning down graphite (top-down) and building up from carbon (bottom-up). A 2020 review (Backes et al.) sets out production and processing methods and the characterisation procedures in practical, reproducible detail Sourced [Ref. 9]. Below, the differences that matter for material quality are lined up with reported values.

Values are as stated in each paper's abstract. Conditions (solvent, substrate, feedstock, method) differ, so the table does not rank the routes.

4. Our calculation: what is left after oxidation and reduction

Reducing graphene oxide is the route that most easily gives dispersions or powders in bulk from graphite. Using Stankovich et al.'s numbers, let us count how far "reduced graphene" sits from an ideal sheet Our calculation.

5. Reading quality by Raman — layer count and defect indicators

The most common quality check on graphene is Raman spectroscopy, in which laser light probes the vibrations of the carbon lattice. A 2013 review by Ferrari and Basko says Raman can determine the number and orientation of layers, the quality and types of edge, and the effects of electric and magnetic fields, strain, doping, disorder and functional groups Sourced [Ref. 16].

• Layer count: Ferrari et al. (2006) reported that the shape, width and position of the 2D band (second order of the D band) change with the number of layers, and the G band shifts slightly down, allowing non-destructive, high-throughput identification of layers Sourced [Ref. 17].
• Amount of defects: Cançado et al. (2011), working on Ar⁺-bombarded graphene, showed that for a given defect density the ratio of D to G peak intensities (ID/IG) depends strongly on laser excitation energy. ID/IG peaks at an inter-defect distance of about 3 nm, so one ratio can correspond to two different defect densities; the width of the G peak resolves the ambiguity Sourced [Ref. 18].
• Type of defect: Eckmann et al. (2012) reported that the D to D′ intensity ratio is largest for sp³ defects (about 13), about 7 for vacancy-like defects and smallest (about 3.5) for boundaries in graphite Sourced [Ref. 19].

6. A materials engineer's view (1): what to check on a "graphene" specification

The methods follow the Kauling survey of 60 producers and the Backes review; arranging them into items is this article's own commentary.

7. Applications — batteries, composites, inks and thermal management by stage

For each application, what has been reported is separated from how far it has progressed. Commercial adoption is stated only where public or company-official material could confirm it; what could not be confirmed is listed in Chapter 10.

(1) Conductive additive in batteries — bridging with a plane

A conductive additive links active-material particles and builds paths for electrons. Whereas particulate additives touch particles at points, Su et al. describe the graphene network as a "plane-to-point" contact mode, with a thin, flexible planar structure favouring electron transport Sourced [Ref. 23].

View the original SVG schematic and exact annotations

Reading guide and original schematic labels: Contact modes of conductive additives (concept) / Left: particulate additive (point contact). Right: planar graphene additive (plane contacts particles) / Particulate additive (point to point) / Planar additive (plane-to-point) / Touch at small points / One sheet covers and links several particles / The contact-mode contrast is a concept described by Su et al. / * Particle size, number and layout are schematic; not an electrode cross-section, nor additive amounts or performance.

What practitioners should watch is how hard it is to disperse graphene through a whole electrode. Son et al.'s graphene ball is a three-dimensional assembly grown by CVD around silica particles, and they coat it onto cathode particles by "Nobilta" milling (a dry powder-processing method) Sourced [Ref. 24]. The paper presents this as showing the possibility of reaching 800 Wh/L in a commercial cell; it is not a record of commercialisation Not yet confirmed.

(2) Composites — the interface matters more than the number

The monolayer strength in Chapter 2 only counts once the graphene is dispersed in a matrix and load passes from the matrix into it. For composites with carbon nanotubes or graphene, Kinloch et al. name poor load transfer, interface design, dispersion and viscosity-related processing difficulty as the issues, and say there has been little effort to identify selection rules for particular applications Sourced [Ref. 25]. Powder made by oxidation and reduction can restack so that specific surface area falls to about 18% of the theoretical value in one example (Chapter 4), so re-exfoliation during dispersion becomes a design item on the materials side (Commentary).

(3) Inks — the pairing of annealing and substrate

Printing inks are an application of the liquid-phase dispersions in Chapter 3 (route 2). Torrisi et al.'s printed film had about 80% transmittance and about 30 kΩ/sq, and Secor et al.'s film reached 4 mΩ·cm after 250 °C annealing Sourced [Ref. 27, 28]. The same "graphene ink" can differ by an order of magnitude or more depending on solvent, stabiliser and heat treatment; this connects to the biosensor article's section on transfer residue and ink annealing temperature.

(4) Thermal management — read "graphene" and "graphite sheet" separately

In-plane heat spreading is a representative proposed application of graphene. But values obtained under different conditions are mixed together.

Values from different samples, methods and directions are set side by side; this is not a ranking. The single-layer value and the values for macroscopic films and sheets are different quantities.

Using the table on the Panasonic page, let us calculate what happens when thickness changes within one product family Our calculation.

8. Transfer and scale-up — making it versus putting it where it is used

CVD graphene on copper foil has to be moved to where it will be used (a silicon wafer, glass, a film). The Backes review says that single-layer graphene from CVD on metals or from molecular bottom-up routes must be transferred to the final substrate, and that advances in large-area, high-quality growth must be matched by advances in transfer Sourced [Ref. 9]. Etch-based transfer of the metal is reliable but time- and resource-consuming, and damages the graphene and leaves metal and etchant residues; electrochemical delamination and dry transfer are named as alternatives (dry transfer being less detrimental to quality and allowing deterministic placement) Sourced [Ref. 9].

View the original SVG schematic and exact annotations

Reading guide and original schematic labels: Wet transfer of CVD graphene and where quality is lost (concept) / A typical flow using a PMMA support film (Suk et al.). Step names are simplified / 1 Growth / 2 Support film / 3 Remove copper / 4 Place / 5 Remove film / Graphene film on / copper foil / Spin-coat PMMA / Dissolve the copper / in etchant / Scoop it onto the / target substrate / Remove the polymer / with solvent / Where quality suffers (grouped from the papers and the review) / Polymer layer / PMMA is the / typical example / Damage, metal residue / Etch transfer can / tear the film and / leave residue / Cracks, wrinkles / Suk et al. report / fewer cracks and / tears on flat substrates / Chemical residue / Residue after transfer / alters physical and / electrical properties / * Flow after Suk et al. [Ref. 32]; damage and residue: Backes et al. [Ref. 9]; residue effect: Pirkle et al. [Ref. 33]. / * Actual conditions, chemicals and order differ by method. Electrochemical delamination and dry transfer are alternatives.

Suk et al. presented dry and wet transfer with a PMMA support film as reproducible methods, reporting 98% of 2.7 µm holes in a perforated substrate covered by a continuous film, fewer cracks and tears on flat substrates, and, for a monolayer film on glass, a sheet resistance of about 980 Ω/sq with 97.6% transmittance Sourced [Ref. 32]. That chemical residue remaining after transfer affects physical and electrical properties is the subject of the paper by Pirkle et al. (by its title) Sourced [Ref. 33].

On scale-up, Bae et al. made 30-inch films roll to roll and reported a sheet resistance of about 125 Ω/sq with 97.4% transmittance Sourced [Ref. 34]. On integration into semiconductor lines, Neumaier et al. state that integrating an unconventional material such as graphene into an established fabrication line is a critical step towards commercialisation Sourced [Ref. 35] (we confirmed only the summary). For large single-crystal films, Xu et al. report growing a (5 × 50) cm² film in 20 minutes Sourced [Ref. 8].

9. A materials engineer's view (2): reading numbers by sample state

10. What could not be confirmed / how this fits with other articles in the series

(1) What we could not confirm within the scope of this article

• Public or company-official material showing that graphene is used as a standard conductive additive in commercial battery cells could not be confirmed. The battery values in Chapter 7 are laboratory or prototype-cell reports Not yet confirmed.
• Primary sources for guaranteed property values in production composites and for the market price or production cost of graphene powder could not be confirmed.
• The Panasonic product page gave no direction or method of measurement for thermal conductivity that we could confirm. The calculation in Chapter 7 assumes in-plane.
• We did not confirm the production scale or quality control of flash graphene and other direct-synthesis routes beyond the papers. HydroGraph's page gives no figures such as carbon purity, so none appears here.
• The text of standards such as ISO/TS 21356-1 is paywalled, so we limited ourselves to what the catalogue pages say.

(2) Safety, and the sensor side

The safety of graphene-based materials is not settled by the name of the material. The review by Fadeel et al. says that not all graphene-based materials are alike and that it is essential to disentangle the structure-activity relationships Sourced [Ref. 36]. Handling safety of powders has to be checked for each shape, size, surface and oxygen content, and this article gives no individual advice. For sensors (electrodes, FETs, anchoring of recognition elements, the Debye length) and for the assessments of carbon nanotubes by international bodies, see our biosensor explainer on graphene and carbon nanotubes. The material side of carbon nanotubes (production, chirality, separation, applications) is covered in our explainer on carbon nanotubes.

11. Glossary

12. Primary sources

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13. Claim-to-source audit

Last updated 9 October 2026. Sources are limited to primary material (peer-reviewed papers, ISO standard pages and manufacturers' product pages). Because the article includes materials-design interpretations, those are marked as Commentary and kept separate from sourced fact. Standard adoption in battery cells, guaranteed values in production composites, powder prices, the production status of direct synthesis and the measurement direction for Panasonic PGS conductivity are not stated because no primary source could be confirmed. The values in the tables of Chapters 2 and 7 differ in sample, method and direction and are not a ranking. All figures are explanatory concept graphics. Figs. 1 to 4 and 6 to 8 are vector drawings (Figs. 3 and 7 include our calculation); the hero image and Fig. 5 are AI-generated images, and none of them shows a real micrograph, spectrum or physical product.