MXene Ti3C2Tx layered structure with intercalated electrolyte ions delivering greater than 1500 F per cubic centimeter volumetric capacitance in supercapacitor electrodes, paired with graphene-based EDLC electrodes

Graphene and MXene Supercapacitor Electrodes

By , Founder, Cheap Tubes Inc. & CTI Materials LLC.

Part of the Graphene & CNT Battery Applications hub.

TL;DR

Graphene nanoplatelets, reduced graphene oxide, and MXene (Ti3C2Tx) serve as high-surface-area electrodes in electrochemical double-layer capacitors (EDLCs) and pseudocapacitors. Graphene provides up to 2,630 m²/g theoretical surface area; practical electrodes achieve 200–700 m²/g. MXene contributes both double-layer capacitance and surface-redox pseudocapacitance, achieving volumetric capacitances above 1,500 F/cm³ in optimized films — among the highest reported for any electrode material. This page covers EDLC vs pseudocapacitor selection, material-grade choice, and procurement considerations for graphene and MXene supercapacitor electrodes.

EDLC vs pseudocapacitor vs hybrid

Supercapacitors store charge by three distinct mechanisms, and the right carbon material depends on which mechanism dominates:

Electrochemical double-layer capacitors (EDLCs). Charge is stored physically at the electrode-electrolyte interface — no chemical reaction, just ion adsorption on a high-surface-area substrate. Energy density is modest (5–10 Wh/kg) but power density is very high (5,000–10,000 W/kg) and cycle life is essentially unlimited (106+ cycles). EDLCs use porous carbon, activated carbon, graphene, or rGO as the electrode material.

Pseudocapacitors. Charge is stored via fast, reversible surface redox reactions in addition to double-layer adsorption. Energy density is higher than EDLCs (10–30 Wh/kg) at moderate cost in cycle life (104–105 cycles). Common pseudocapacitive materials: MnO2, RuO2, conductive polymers, and (notably) MXene Ti3C2Tx.

Hybrid supercapacitors. Combine an EDLC electrode (carbon, high power) with a battery-like electrode (lithium intercalation material, high energy). Energy density approaches 50 Wh/kg with power density retained at 1,000–5,000 W/kg. Hybrid devices increasingly dominate commercial supercapacitor product launches in 2024–2026.

The trade-offs determine material choice. For pure EDLC: maximize surface area and conductivity. For pseudocapacitor: choose a material with reversible surface redox at the operating voltage. For hybrid: carbon electrode is typically graphene-based; battery electrode follows lithium-ion design.

Three supercapacitor charge storage mechanisms: EDLC physical ion adsorption with carbon electrodes giving 5-10 Wh/kg energy and 10 to the 6 cycles, pseudocapacitor surface redox with MXene Ti3C2 giving 10-30 Wh/kg, hybrid combining EDLC carbon electrode with lithium-ion battery electrode for ~50 Wh/kg
Three supercapacitor mechanisms – EDLC, pseudocapacitor, and hybrid – each suits a different carbon material grade.

Why surface area and conductivity = supercap performance

Specific capacitance (F/g) at the EDLC electrode is proportional to electrochemically accessible surface area times the dielectric capacitance of the electrolyte double layer. Practical EDLC carbons deliver 100–250 F/g in aqueous electrolyte and 80–200 F/g in organic electrolyte. Graphene and rGO can exceed 300 F/g in optimized configurations.

Two surface-area caveats matter:

  1. Pore size matters more than total surface area. Pores smaller than the solvated ion (1–2 nm for organic electrolytes, 0.5–1 nm for aqueous) contribute little to capacitance because ions cannot access them. Optimal carbon electrodes have a hierarchical pore structure: meso-pores for ion transport plus narrow micro-pores tuned to the solvated ion size for high-density adsorption.
  2. Conductivity sets the rate ceiling. A high-surface-area carbon with poor conductivity delivers excellent low-rate capacitance but cannot maintain it at high rates. Graphene and MXene have intrinsic in-plane conductivities orders of magnitude higher than activated carbon, which is the reason they dominate high-power supercapacitor research.

For graphene specifically, the practical challenge is that graphene sheets restack into multilayer assemblies during electrode fabrication — losing most of the theoretical surface area. Successful graphene supercapacitor electrodes use spacers (curved sheets, nanotube intercalation, polymer linkers) to prevent restacking and maintain accessible surface area.

Comparison showing pristine graphene restacking into multilayer stacks losing 95 percent of theoretical surface area giving only 50-100 F per gram, versus spaced graphene with CNT spacers preserving 50-70 percent surface area accessibility delivering 200-300 F per gram capacitance
Pristine graphene restacks during drying losing surface area – CNT spacers, polymer linkers, or 3D structures preserve accessibility.

Material-by-material breakdown

Graphene nanoplatelets (GNP) and few-layer graphene. Conductive backbone for EDLC electrodes. Practical specific capacitances 120–200 F/g in aqueous electrolyte at moderate rates. Lower capacitance than activated carbon at low rates, but far higher rate capability and far better cycle stability. Common pairing: GNP + activated carbon hybrid composite, which combines GNP’s conductivity with activated carbon’s surface area. Available from Cheap Tubes’ GNP catalog.

Graphene oxide (GO). Used primarily as a precursor for reduced graphene oxide electrodes. GO itself is electrically insulating because of the oxygen functional groups; it must be reduced to rGO before use as a supercap electrode. GO’s solubility in water and aqueous binders makes it the easiest graphene-family material to process at scale. Available via Cheap Tubes’ GO catalog.

Reduced graphene oxide (rGO). Conductivity restored, defect density tunable via reduction conditions. Practical capacitances 150–250 F/g. rGO defects are sometimes beneficial — they introduce pseudocapacitive contributions from residual oxygen groups, raising total capacitance. rGO is the most common graphene-family electrode in published supercapacitor work.

MXene Ti3C2Tx. The standout 2D material for pseudocapacitors. Layered structure with intercalated water and surface-terminating groups (-O, -OH, -F denoted Tx) that participate in reversible surface redox. Volumetric capacitances exceed 1,500 F/cm³ in dense films — among the highest reported for any electrode material. Areal capacitances of 1–2 F/cm² in thick coatings. Limitations: oxidative degradation in ambient air over long storage; performance dependent on synthesis-induced surface chemistry. Available via Cheap Tubes’ MXene category.

Composite electrodes. Most published high-performance supercap electrodes combine two or more carbon morphologies — for example, GNP backbones interleaved with activated carbon spacers, or MXene + CNT pillared structures that prevent MXene restacking. Hybrid electrodes are the current state-of-the-art for commercial-grade performance.

MXene Ti3C2Tx layered structure showing three layers of titanium carbide with surface terminations T_x (-O, -OH, -F) on top and bottom faces and intercalated cations between layers, contributing both double-layer capacitance from surface area and pseudocapacitance from titanium surface redox
MXene Ti3C2Tx delivers two simultaneous charge storage mechanisms: double-layer capacitance plus surface redox pseudocapacitance.

Pseudocapacitive contributions of MXene

MXene’s high volumetric capacitance comes from two simultaneous mechanisms:

  1. Double-layer capacitance from the high accessible surface area between layered Ti3C2Tx sheets — comparable to a high-quality EDLC carbon.
  2. Surface-redox pseudocapacitance from oxidation-state changes of surface Ti atoms in the presence of protons or other cations. The functional groups (-O, -OH, -F) on the MXene surface modulate the redox potential and the available redox capacity. This is the contribution that distinguishes MXene from a pure-EDLC graphene electrode.

The combined effect is volumetric capacitance several times that of activated carbon or pristine graphene, with rate capability that scales with the in-plane MXene conductivity. The technology trade-offs: MXene cost is higher than graphene-family materials, and ambient-air stability is more limited (storage and processing require inert or controlled atmospheres for the highest-quality grades).

For supercapacitor R&D and commercial development teams evaluating MXene, the practical specifications to check are: Ti3C2Tx layer count (mono vs few-layer), surface termination distribution (-O, -OH, -F ratio), and pre-intercalation state (delaminated vs multilayer).

Three-panel diagram showing pore size effects: pore too small excludes solvated ions losing surface area, pore matched to solvated ion gives maximum charge density at sweet spot 0.5-2 nm, pore too large reduces ion density per volume
Pore size matching determines real capacitance – pores must accept the solvated ion without excluding it.

Material specs for supercap electrodes

MaterialPractical capacitance (F/g)Best applicationNotes
GNP (5–25 µm lateral, 5–15 nm)100–180EDLC conductive backboneRestacking is the main loss mechanism
rGO (0.5–5 µm lateral)150–250EDLC + mild pseudocapDefect-stabilized, easy to process
GO(precursor only)Reduce to rGO in situWater-soluble, easy slurry processing
MXene Ti3C2Tx300–500 (mass), 1,500 F/cm³ (vol)Pseudocapacitor, hybridHighest volumetric capacitance; air-stability caveat
Activated carbon + GNP composite200–280Commercial EDLCBest cost-performance for production

Loading in the final electrode is typically 70–95 wt% active carbon material, 5–15 wt% binder (PTFE or PVDF), 0–10 wt% conductive additive (carbon black or CNT). For composite electrodes, mass ratios of the carbon components are typically optimized empirically.

Bar chart of specific capacitance F per gram across activated carbon (100-200), GNP (100-180), rGO (150-250), AC plus GNP composite (200-280), and MXene Ti3C2Tx (300-500 gravimetric, 1500 plus volumetric F per cubic centimeter)
MXene Ti3C2Tx delivers 300-500 F/g gravimetric and 1500+ F/cm³ volumetric capacitance – 2-5x better than graphene-only electrodes.

For pilot or production-scale electrode coating, dispersion uniformity again drives yield. Surfactant-stabilized Flexiphene formulations are well-suited to graphene and rGO supercapacitor electrode coatings where standard NMP-based dispersion would otherwise re-bundle.

Polyaniline and polymer-composite electrodes. A growing fraction of pseudocapacitor electrode formulations combine MXene or graphene with conductive polymers — particularly polyaniline (PANI) — that contribute both pseudocapacitance and mechanical robustness. CTI Materials holds patent coverage (U.S. Patents 10,049,783 and 11,961,630) on CNT + graphene/GO/GNP composites with polyaniline, polyaminotriazole, polyimide, polyamide, nylon, and polyester polymer matrices. For supercapacitor R&D and production buyers integrating conductive-polymer composites, the Flexiphene patented dispersion technology provides validated formulations covering these exact polymer-nanocarbon chemistries.

Cheaptubes products for supercapacitor applications

For custom MXene or graphene specifications, contact Cheap Tubes Inc. directly.

Authoritative external references

  • Stoller, M. D. et al. — graphene-based ultracapacitors (2008) (Nano Letters)
  • Lukatskaya, M. R. et al. — MXene for high-power supercapacitors (2013) (Science)
  • Ghidiu, M. et al. — clay-like MXene with high volumetric capacitance (2014) (Nature)
  • Raccichini, R. et al. — graphene/GO/rGO in batteries and electrochemical capacitors, critical review (2015) (Nature Materials)
  • Bonaccorso, F. et al. — graphene for batteries, supercapacitors and beyond (2016) (Nature Reviews Materials)
  • Anasori, B. et al. — review of 2D MXenes for energy storage (2017) (Nature Reviews Materials)
  • Simon, P. & Gogotsi, Y. — perspectives on supercapacitors (2020) (Nature Materials)
  • Comprehensive review — electrochemical energy storage applications of graphene oxide including supercapacitors (2024) (Energy & Fuels)

(External links reflect representative peer-reviewed literature; no endorsement implied.)

Frequently asked questions

Graphene or MXene — which is better for supercapacitors?

It depends on the metric. For gravimetric capacitance and cost, graphene-family materials (GNP, rGO) lead. For volumetric capacitance and pseudocapacitive contribution, MXene Ti3C2Tx is best-in-class. For commercial production, graphene-based EDLCs dominate by cost; MXene leads in volumetric energy density for R&D and emerging applications.

Why doesn’t pristine graphene match its theoretical capacitance?

Restacking. Graphene sheets attract each other strongly during electrode drying — multi-layer assemblies form that lose most of the theoretical surface area. Successful electrodes use spacers (CNT intercalation, polymer linkers, hierarchical structures) to keep sheets separated and surface area accessible.

Can MXene be used in aqueous and organic electrolytes?

Yes to both, with different performance characteristics. Aqueous electrolytes deliver the highest pseudocapacitive contribution (proton-mediated surface redox). Organic electrolytes enable higher operating voltage windows but reduce pseudocapacitance. Ionic-liquid electrolytes are increasingly used for high-voltage MXene cells.

How stable is MXene in ambient air?

Pristine Ti3C2Tx MXene degrades over weeks-to-months in ambient air, particularly in humid conditions. Storage under inert atmosphere or in solvent dispersions slows degradation. Surface-functionalized MXene variants and protective coatings are active development areas for improving shelf life.

What’s the role of carbon black in supercap electrodes?

In most commercial supercapacitor electrodes, the active carbon (activated carbon, graphene, rGO) provides most of the capacitance, and 5–15 wt% carbon black is added for electrical connectivity to the current collector. Replacing carbon black with CNT or graphene in the conductive-additive role can reduce loading while improving rate capability — same percolation argument as in lithium-ion cathodes.

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About the author

is the founder of Cheap Tubes Inc. and CTI Materials LLC. He holds 2 granted U.S. patents (10,049,783 and 11,961,630) in carbon nanomaterial applications, with additional patents in prosecution. His patented materials were selected by NASA for the Enceladus mission as a dual-capacitance layer in ion-selective electrodes. Mike has supplied carbon nanomaterials to battery R&D and production for 21 years.