Simple Slurry-Coating Trick Yields MXene-Polyaniline Electrode That Endures 10,000 Charge Cycles

Supercapacitors promise bursts of power delivered in seconds, but the materials inside them have long forced engineers into an uncomfortable trade-off: cheap electrodes store little energy, while high-performance electrodes often demand elaborate, expensive chemistry. A new study from researchers at VIT-AP University in Amaravati, India, published in the journal Ionics, argues that the way forward may be refreshingly simple. By combining a two-dimensional titanium carbide material known as MXene with the conducting polymer polyaniline, and then simply coating the mixture onto a graphite sheet, Thontadharyadeekshith M and Senthil Karuppanan produced an electrode that stores 406 farads per gram, survives 10,000 charge-discharge cycles with most of its capacity intact, and requires nothing more exotic than a slurry-coating step to make.

The star of the study is the MXene, a family of two-dimensional carbides and nitrides first discovered by etching layered ceramics into atomically thin flakes. Unlike graphene, which is pure carbon, MXenes carry a menagerie of surface terminations, including oxygen, fluorine, and hydroxyl groups, that make them hydrophilic and electrically conductive. That combination has made them one of the most closely watched electrode materials of the past decade. Yet MXenes carry a stubborn flaw: their flat, sticky sheets love to restack, collapsing into dense layers that block the electrolyte from reaching much of the stored charge. A supercapacitor electrode, after all, works only where ions can go, and a restacked film is an ion-proof fortress.

The Indian team’s answer was to wedge polyaniline between the MXene sheets. Polyaniline, or PANI, is one of the oldest and cheapest conducting polymers, prized for its ease of synthesis and its ability to store charge through fast, reversible redox reactions. When the two materials share an electrode, each covers the other’s weaknesses. The MXene supplies a robust, metallically conductive scaffold and mechanical resilience; the polymer chains pry the sheets apart, preventing restacking, and add pseudocapacitance of their own. Field-emission scanning electron microscopy in the new work confirmed the outcome: the polymer effectively suppressed MXene restacking and generated a porous, interconnected architecture that lets ions move freely through the film.

The fabrication route is the study’s quiet revolution. Rather than growing polymers directly on the MXene surface through in-situ polymerization, grafting, or supercritical fluid processing, techniques that many earlier MXene-PANI papers have relied on, the researchers prepared a composite slurry and coated it onto a graphite substrate. Slurry coating is the same workhorse method used to mass-produce lithium-ion battery electrodes, which means the approach inherits an industrial pedigree that laboratory-only synthesis routes lack. The authors describe the method as simple, cost-effective, and scalable, and they deliberately set out to establish a correlation between the structural, morphological, and electrochemical properties of the resulting films, connecting what the material looks like to how it performs.

The electrochemical numbers are where the synergy becomes measurable. The composite electrode delivered a specific capacitance of 406 farads per gram at a current density of 0.5 amperes per gram, a figure that comfortably exceeded what the researchers measured for pristine MXene and pristine polyaniline electrodes prepared the same way. Specific capacitance measures how much charge an electrode can store per unit mass, and values above 400 farads per gram at modest current densities place the material among the competitive performers in the aqueous supercapacitor literature. Just as important, the electrode showed improved rate capability, meaning it held onto a substantial fraction of that capacitance even when charged and discharged faster, a property that matters enormously for real devices that must deliver power in bursts rather than at leisure.

Impedance measurements added a third pillar of evidence. The composite exhibited low internal resistance, which the authors attribute to the synergistic interaction between the conductive MXene layers and the PANI chains. In an electrode, internal resistance is the enemy of both power and efficiency: every ohm lost inside the material turns charging energy into waste heat and slows the delivery of current. By facilitating rapid electron transport along the metallic MXene sheets and efficient electrolyte penetration through the polymer-opened pores, the hybrid architecture attacks resistance from both directions at once, the electronic and the ionic.

Durability, the graveyard of many promising pseudocapacitive materials, is where the study delivers its most striking result. After 10,000 full charge-discharge cycles, the electrode retained 85.4 percent of its initial capacitance and maintained a coulombic efficiency of 95.1 percent. Coulombic efficiency measures how much of the charge pumped into the electrode comes back out on each cycle, and values in the mid-nineties indicate that parasitic side reactions, the slow chemical leaks that degrade electrodes and electrolytes, are being kept firmly in check. For a polymer-containing electrode, which might otherwise swell, crack, or shed material over thousands of cycles, that level of stability suggests the MXene scaffold is doing real mechanical work, anchoring the polymer chains as they repeatedly accept and release ions.

The physical chemistry behind that synergy is worth unpacking. Supercapacitors store charge in two complementary ways. Electric double-layer capacitance accumulates ions at the electrode surface, a process that is fast but limited by available area. Pseudocapacitance, by contrast, involves fast surface redox reactions in which the electrode material itself changes oxidation state, storing far more charge per unit of surface. MXenes contribute both mechanisms, thanks to their conductive sheets and their redox-active surface terminations, while polyaniline is a pseudocapacitive workhorse that shuttles between distinct protonated and deprotonated states. In the hybrid, the polymer’s redox capacity is wired directly into the MXene’s conductive network, so electrons generated in the polymer have an immediate highway out of the film, and ions arriving from the electrolyte find a porous, wetted landscape rather than a sealed stack of sheets.

Context matters for judging the advance. MXene-PANI composites have been reported before, including organ-like Ti3C2 architectures made by chemical grafting, hierarchical hybrids on carbon fibers, and self-assembled films in which polymer nanoparticles open ion-transport channels between sheets. Many of those routes, however, involve multi-step synthesis, specialized reagents, or processing conditions that complicate scale-up. The new work does not claim a record capacitance; instead, its contribution is methodological and diagnostic, demonstrating that a straightforward slurry-coating route can produce an electrode whose performance rivals composites made by far more convoluted chemistry, while explicitly mapping the link between microstructure and electrochemistry. In a field where reproducibility and manufacturability often lag behind headline numbers, that emphasis is significant.

The broader stakes are considerable. Flexible and wearable electronics, regenerative braking systems, grid buffering for renewable power, and fast-charging transport all need storage devices that tolerate high power and hundreds of thousands of shallow cycles, a niche where supercapacitors outperform batteries. Electrode materials that combine high capacitance, low resistance, and long cycle life, made by processes compatible with existing coating lines, are the raw material of that future. The VIT-AP team, supported by the university’s RGEMS grant and a Collaborative Research Scheme project from UGC-DAE CSR, has shown that one of the most celebrated material pairings in electrochemistry can be brought to life with a method simple enough to be handed to a factory. If the slurry-coated MXene-polyaniline architecture can be translated from graphite substrates in the laboratory to full devices on production lines, the humble coating step may prove to be the most consequential part of the whole supercapacitor.

Subject of Research: MXene/polyaniline composite electrodes for supercapacitor energy storage

Article Title: Facile fabrication of a MXene/PANI hybrid electrode for enhanced electrochemical performance in supercapacitors

Article References: Facile fabrication of a MXene/PANI hybrid electrode for enhanced electrochemical performance in supercapacitors. (n.d.). https://doi.org/10.1007/s11581-026-07545-5

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07545-5

Keywords: MXene, polyaniline, supercapacitor, energy storage, electrode materials, pseudocapacitance, slurry coating, electrochemistry, two-dimensional materials, cycle stability, specific capacitance, conducting polymers