Flexible Carbon Dots-Intercalated MXene Film Electrode with Outstanding Volumetric Performance for Supercapacitors

2D MXenes have emerged as promising supercapacitor electrode materials due to their metallic conductivity, pseudo-capacitive mechanism, and high density. However, layer-restacking is a bottleneck that restrains their ionic kinetics and active site exposure. Herein, a carbon dots-intercalated strategy is proposed to fabricate flexible MXene film electrodes with both large ion-accessible active surfaces and high density through gelation of calcium alginate (CA) within the MXene nanosheets followed by carbonization. The formation of CA hydrogel within the MXene nanosheets accompanied by evaporative drying endow the MXene/CA film with high density. In the carbonization process, the CA-derived carbon dots can intercalate into the MXene nanosheets, increasing the interlayer spacing and promoting the electrolytic diffusion inside the MXene film. Consequently, the carbon dots-intercalated MXene films exhibit high volumetric capacitance (1244.6 F cm⁻³ at 1 A g⁻¹), superior rate capability (662.5 F cm⁻³ at 1000 A g⁻¹), and excellent cycling stability (93.5% capacitance retention after 30 000 cycles) in 3 m H₂SO₄. Additionally, an all-solid-state symmetric supercapacitor based on the carbon dots-intercalated MXene film achieves a high volumetric energy density of 27.2 Wh L⁻¹. This study provides a simple yet efficient strategy to construct high-volumetric performance MXene film electrodes for advanced supercapacitors.     

3D Porous Oxidation-Resistant MXene/Graphene Architectures Induced by In Situ Zinc Template toward High-Performance Supercapacitors

2D MXene materials have attracted intensive attention in energy storage application. However, MXene usually undergoes serious face-to-face restacking and inferior stability, significantly preventing its further commercial application. Herein, to suppress the oxidation and self-restacking of MXene, an efficient and fast self-assembly route to prepare a 3D porous oxidation-resistant MXene/graphene (PMG) composite with the assistance of an in situ sacrificial metallic zinc template is demonstrated. The self-assembled 3D porous architecture can effectively prevent the oxidation of MXene layers with no evident variation in electrical conductivity in air at room temperature after two months, guaranteeing outstanding electrical conductivity and abundant electrochemical active sites accessible to electrolyte ions. Consequently, the PMG-5 electrode possesses a striking specific capacitance of 393 F g⁻¹, superb rate performance (32.7% at 10 V s⁻¹), and outstanding cycling stability. Furthermore, the as-assembled asymmetric supercapacitor possesses a pronounced energy density of 50.8 Wh kg⁻¹ and remarkable cycling stability with a 4.3% deterioration of specific capacitance after 10 000 cycles. This work paves a new avenue to solve the two long-standing significant challenges of MXene in the future.     

Controllable Patterning of Porous MXene (Ti3C2) by Metal-Assisted Electro-Gelation Method

Since discovered in 2011, transition metal carbides or nitrides (MXenes) have attracted enormous attention due to their unique properties. Morphology regulation strategies assembling 2D MXene sheets into 3D architecture have endowed the as-formed porous MXene with a better performance in various fields. However, the direct patterning strategy for the porous MXene into integration with multifunctional and multichannel electronic devices still needs to be investigated. The metal-assisted electro-gelation method the authors propose can directly generate porous-structured MXene hydrogel with a tunable feature. By electrolyzing the sacrificial metal, the released metal cations initiate the electro-gelation process during which electrostatic interactions occur between cations and the MXene sheets. A high spatial resolution down to micro-meter level is achieved utilizing the method, enabling high-performance hydrogels with more complex architectures. Electronics prepared through this metal-assisted electro-gelation process have shown promising applications of the porous MXene in energy and biochemical sensing fields. Energy storage devices with a capacitance at 33.3 mF cm⁻² and biochemical sensors show prominent current responses towards metabolites (sensitivity of H₂O₂: 165.6  µ A mm ⁻¹ cm⁻²; sensitivity of DA: 212 nA  µ m ⁻¹ cm⁻²), suggesting that the metal-assisted electro-gelation method will become a prospective technique for advanced fabrication of MXene-based devices.     

Joint-Inspired Liquid and Thermal Conductive Interface for Designing Thermal Interface Materials with High Solid Filling yet Excellent Thixotropy

For advanced thermal interface materials (TIMs), massive inorganic addition for high isotropic thermal conductivities conflicts with suitable rheological viscosity for low contact thermal resistance. Traditional strategies rarely resolve such a contradiction, and it remains an academic and industrial challenge. Herein, inspired by the structure and function of the bone joint, a best-of-both-worlds approach is reported that endows a standard polydimethylsiloxane/alumina (PDMS/Al₂O₃) TIM with simultaneously enhanced rheological mobility and thermal conductivity. It is conducted by employing morphology-controllable gallium-based liquid metal (LM) to the surface of Al₂O₃ by a scalable mechanochemical process. At the typical polymer-LM-Al₂O₃ interface, LM droplets with low cohesive energy can release the freedom for macromolecular chain relaxation and reduce the viscosity, successfully allowing the high-loading TIMs (79 vol.%) to keep the thixotropic state and effectively reducing its contact thermal resistance with a copper substrate by 65%. At the same time, adjacent LMs merge to thermally bridge separate Al₂O₃ particles, which facilitates the interfacial thermal conduction and enhances the thermal conductivity from 5.9 to 6.7 W m⁻¹ K⁻¹. Along with additional electrical insulation, this filler modification strategy is believed to inspire others to develop high-performance polymer-based TIMs for future advanced electronics.     

Industry-Scale and Environmentally Stable Ti3C2Tx MXene Based Film for Flexible Energy Storage Devices

MXenes, 2D transition metal carbides, and nitrides have attracted tremendous interest because of their metallic conductivity, solution processability, and excellent merits in energy storage and other applications. However, the pristine MXene films often suffer from poor ambient stability and mechanical properties that stem from their polar terminal groups and weak interlayer interactions. Here, a heteroatom doping strategy is developed to tailor the surface functionalities of MXene, followed by the addition of large-sized reduced graphene oxide (rGO) as conductive additives to achieve a scalable production of S, N-MXene/rGO (SNMG-40) hybrid film with high mechanical strength ( ≈ 45 MPa) and energy storage properties (698.5 F cm⁻³). Notably, the SNMG-40 film also demonstrates long-term cycling stability ( ≈ 98% capacitance retention after 30 000 cycles), which can be maintained under ambient condition or immersed in H₂SO₄ electrolyte for more than 100 days. The asymmetric supercapacitor (aMGSC) based on SNMG-40 film shows an ultrahigh energy density of 22.3 Wh kg⁻¹, which is much higher than those previously reported MXene-based materials. Moreover, the aMGSC also provides excellent mechanical durability under different deformation conditions. Thus, this strategy makes MXene materials more competitive for real-world applications such as flexible electronics and electromagnetic interference shielding.     

Nature-Inspired Interconnected Macro/Meso/Micro-Porous MXene Electrode

The geometric multiplication development of MXene has promoted it to become a star material in numerous applications including, but not limited to, energy storage. It is found that pore structure modulation engineering can improve the inherent properties of MXene, in turn significantly enhancing its electrochemical performance. However, most of the current works have focused on exploring the structure-effective relationships of the single-scale pore structure regulation of MXene. Inspired by Murray's law from nature where a highly graded structure of the organisms is discovered and used to achieve effective diffusion and maximize mass transfer, a hierarchically interconnected porous MXene electrode across micro-meso-macroporous is constructed. This MXene-based electrode provides large amounts of active sites while greatly shortening the ion diffusion channel. Finally, the zinc ion microcapacitor based on this MXene electrode exhibits an ultrahigh area-specific capacitance up to 410 mF cm⁻² and an energy density up to 103 µWh cm⁻² at a power density of 2100 µW cm⁻². The areal energy density outperforms the currently reported zinc ion microcapacitors. This study supports an effective strategy for electrode materials (including but not limited to MXene) to achieve ultra-short ion diffusion channels and maximum transport efficiency for next-generation high-performance energy storage.     

Wearable Janus-Type Film with Integrated All-Season Active/Passive Thermal Management,Thermal Camouflage,and Ultra-High Electromagnetic Shielding Efficiency Tunable by Origami Process

Multifunctional films with integrated temperature adjustment, electromagnetic interference (EMI) shielding, and thermal camouflage are remarkably desirable for wearable products. Herein, a novel Janus-type multifunctional ultra-flexible film is fabricated via continuous electrospinning followed by spraying. Interestingly, in the polyvinyl alcohol (PVA)/phase change capsules (PCC) layer (P₁), the PCC is strung on PVA fibers to form a stable “candied haws stick” structure that obviates slipping or falling off. The film with sufficient melting enthalpy (141.4 J g⁻¹) guarantees its thermoregulation capability. Simultaneously, its high mid-IR emissivity (90.15%) endows the film with radiative cooling properties (reducing temperature by 10.13 °C). Mechanical strength is significantly improved by superimposing a polylactic acid (PLA) layer (P₂) on its surface. By spraying a thin MXene layer on the PLA surface of P₂P₁ film, the obtained (MXene/P₂P₁) MP₂P₁ film is endowed with satisfactory low-voltage heating, photo-thermal and superior thermal camouflage performance, achieving all-season thermal comfort. Impressively, the flexible MP₂P₁ film achieves enhanced EMI shielding effect from 50.3 to 87.8 dB through a simple origami process, which simplifies the manufacturing process of high-performance EMI shielding materials. In brief, the multifunctional Janus-type MP₂P₁ film is an attractive candidate for future wearable products with personalized thermal management and anti-electromagnetic radiation.     

Paper-Mill Waste Reinforced Nanofluidic Membrane as High-Performance Osmotic Energy Generators

Nanofluidic membranes consisting of 2D materials and polymers are considered promising candidates for harvesting osmotic energy from river estuaries owing to their unique ion channels. However, micron-scale polymer chains agglomerate in the nanochannels, resulting in steric hindrance and affection ion transport. Herein, a nanofluidic membrane is designed from MXene and xylan nanoparticles that are derived from paper-mill waste. The demonstrated membrane reinforced by paper-mill waste has the characteristics of green, low-cost, and outstanding performance in mechanical properties and surface-charge-governed ionic transport. The MXene/carboxmethyl xylan (CMX) membrane demonstrates a high surface charge (ζ-potential of −44.3 mV) and 12 times higher strength (284.96 MPa) than the pristine MXene membrane. The resulting membrane shows intriguing features of high surface charge, high ion selectivity, and reduced steric hindrance, enabling it high osmotic energy generation performance. A potential of the nanofluidic membrane is ≈109 mV, the corresponding current of up to 2.73 µA, and the output power density of 14.52 mW m⁻² are obtained under a 1000-fold salt concentration gradient. As the electrolyte pH increases, the power density reaches 56.54 mW m⁻². This works demonstrate that CMX nanoparticles can effectively enhance the properties of the nanofluidic membrane and provide a promising strategy to design high-performance nanofluidic devices.     

Preparation and properties of electrically conductive,flexible and transparent silver nanowire/poly (lactic acid) nanocomposites

As the everyday use of petroleum-based products has raised environmental concerns, there is an urgent need to replace them with green materials. In this work, an eco-friendly, highly conductive, flexible silver nanowire/poly (lactic acid) film has been fabricated through a simple casting method by embedding the silver nanowires (AgNWs) below the surface of the poly lactic acid (PLA) matrix. The fabricated film has a high optical transparency of 89.5% with a sheet resistance of 64.8 Ω/□ and a figure of merit (FoM) of 4.92 × 10⁻³ Ω⁻¹ which is comparable to that of indium tin oxide (ITO). These films demonstrate excellent flexibility, great adhesion, smooth surface with root mean square (RMS) roughness of 11.7 nm and high mechanical properties with tensile strength and Young's modulus of 39.8 (MPa) and 1.6 (GPa). The results obtained from different testing methods show that the AgNW/PLA nanocomposites are potential candidates in flexible electronics and optoelectronics.     

Lightweight,Thermally Insulating,Fire-Proof Graphite-Cellulose Foam

Foam materials are widely used in packaging and buildings for thermal insulation, sound absorption, shock absorption, and other functions. They are dominated by petroleum-based plastics, most of which, however, are not biodegradable nor fire-proofing, leading to severe plastic pollution and safety concerns. Here, a fire-proofing, thermally insulating, recyclable 3D graphite-cellulose nanofiber (G-CNF) foam fabricated from resource-abundant graphite and cellulose is reported. A freeze-drying-free and scalable ionic crosslinking method is developed to fabricate Cu²⁺ ionic crosslinked G-CNF (Cu-G-CNF) foam with a low energy consumption and cost. Moreover, the direct foam formation strategy enables local foam manufacturing to fulfil the local demand. The ionic crosslinked G-CNF foam demonstrates excellent water stability (the foam can maintain mechanical robustness even in wet state and recover after being dried in air without deformation), fire resistance (41.7 kW m⁻² vs 214.3 kW m⁻² in the peak value of heat release rate) and a low thermal conductivity (0.05 W/(mK)), without compromising the recyclability, degradability, and mechanical performance of the composite foam. The demonstrated 3D G-CNF foam can potentially replace the commercial plastic-based foam materials, representing a sustainable solution against the “white pollution”.     

Lamellar MXene Composite Aerogels with Sandwiched Carbon Nanotubes Enable Stable Lithium–Sulfur Batteries with a High Sulfur Loading

Realizing long cycling stability under a high sulfur loading is an essential requirement for the practical use of lithium–sulfur (Li–S) batteries. Here, a lamellar aerogel composed of Ti₃C₂T_x MXene/carbon nanotube (CNT) sandwiches is prepared by unidirectional freeze-drying to boost the cycling stability of high sulfur loading batteries. The produced materials are denoted parallel-aligned MXene/CNT (PA-MXene/CNT) due to the unique parallel-aligned structure. The lamellae of MXene/CNT/MXene sandwich form multiple physical barriers, coupled with chemical trapping and catalytic activity of MXenes, effectively suppressing lithium polysulfide (LiPS) shuttling under high sulfur loading, and more importantly, substantially improving the LiPS confinement ability of 3D hosts free of micro- and mesopores. The assembled Li–S battery delivers a high capacity of 712 mAh g⁻¹ with a sulfur loading of 7 mg cm⁻², and a superior cycling stability with 0.025% capacity decay per cycle over 800 cycles at 0.5 C. Even with sulfur loading of 10 mg cm⁻², a high areal capacity of above 6 mAh cm⁻² is obtained after 300 cycles. This work presents a typical example for the rational design of a high sulfur loading host, which is critical for the practical use of Li–S batteries     

Interconnected Metallic Membrane Enabled by MXene Inks Toward High-Rate Anode and High-Voltage Cathode for Li-Ion Batteries

The ever-increasing popularity of smart electronics demands advanced Li-ion batteries capable of charging faster and storing more energy, which in turn stimulates the innovation of electrode additives. Developing single-phase conductive networks featuring excellent mechanical strength/integrity coupled with efficient electron transport and durability at high-voltage operation should maximize the rate capability and energy density, however, this has proven to be quite challenging. Herein, it is shown that a 2D titanium carbide (known as MXene) metallic membrane can be used as single-phase interconnected conductive binder for commercial Li-ion battery anode (i.e., Li₄Ti₅O₁₂) and high-voltage cathodes (i.e., Ni_0.8Mn_0.1Co_0.1O₂). Electrodes are fabricated directly by slurry-casting of MXene aqueous inks composited with active materials without any other additives or solvents. The interconnected metallic MXene membrane ensures fast charge transport and provides good durability, demonstrating excellent rate performance in the Li//Li₄Ti₅O₁₂ cell (90 mAh g⁻¹ at 45 C) and high reversible capacity (154 mAh g⁻¹ at 0.2 C/0.5 C) in Li//Ni_0.8Mn_0.1Co_0.1O₂ cell coupled with high-voltage operation (4.3 V vs Li/Li⁺). The LTO//NMC full cell demonstrates promising cycling stability, maintaining capacity retention of 101.4% after 200 cycles at 4.25 V (vs Li/Li⁺) operation. This work provides insights into the rational design of binder-free electrodes toward acceptable cyclability and high-power density Li-ion batteries.     

A Bioinspired Polymer-Based Composite Displaying Both Strong Adhesion and Anisotropic Thermal Conductivity

The integration and functionality of high-power electronic architectures or devices require a high strength and good heat flow at the interface. However, simultaneously improving the interfacial bonding and phonon transport of polymers is challenging because of the tradeoff between the cross-linked flexible chains and high-quality crystalline structure. Here, a copolymer, poly(dopamine methacrylate-co-hydroxyethyl methacrylate [P(DMA-HEMA)] is designed and synthesized, inspired by the snail and mussel adhesion. The copolymer achievs a high surface adhesion up to 6.38 MPa owing to the synergistic effects of hydrogen bonds and mechanical interlocking. When the copolymer is introduced into vertically aligned carbon nanotubes (VACNTs), the catechol groups in P(DMA-HEMA) formed strong bonding with the nanotubes through π-π interactions at the interface. As a result, the P(DMA-HEMA)/VACNTs composite shows a high through-plane thermal conductivity (21.46 W m⁻¹ K⁻¹), an in-plane thermal conductivity that is 3.5 times higher than that of pristine VACNTs, and an extremely low thermal contact resistance (20.27 K mm² W⁻¹). Furthermore, the composite forms weld-free high-strength connections between two pieces of various metals to bridge directional thermal pathways. It also exhibits excellent interfacial heat transfer capability and high reliability even under zero-pressure conditions.     

Hyperelastic,Robust, Fire-Safe Multifunctional MXene Aerogels with Unprecedented Electromagnetic Interference Shielding Efficiency

MXene aerogels have shown great potential for many important functional applications, in particular electromagnetic interference (EMI) shielding. However, it has been a grand challenge to create mechanically hyperelastic, air-stable, and durable MXene aerogels for enabling effective EMI protection at low concentrations due to the difficulties in achieving tailorable porous structures, excellent mechanical elasticity, and desired antioxidation capabilities of MXene in air. Here, a facile strategy for fabricating MXene composite aerogels by co-assembling MXene and cellulose nanofibers during freeze-drying followed by surface encapsulation with fire-retardant thermoplastic polyurethane (TPU) is reported. Because of the maximum utilization of pore structures of MXene, and conductive loss enhanced by multiple internal reflections, as-prepared aerogel with 3.14 wt% of MXene exhibits an exceptionally high EMI shielding effectiveness of 93.5 dB, and an ultra-high MXene utilization efficiency of 2977.71 dB g g⁻¹, tripling the values in previous works. Owing to the presence of multiple hydrogen bonding and the TPU elastomer, the aerogel exhibits a hyperelastic feature with additional strength, excellent stability, superior durability, and high fire safety. This study provides a facile strategy for creating multifunctional aerogels with great potential for applications in EMI protection, wearable devices, thermal management, pressure sensing, and intelligent fire monitoring.     

A Robust and Adhesive Hydrogel Enables Interfacial Coupling for Continuous Temperature Monitoring

Continuous temperature monitoring by flexible hydrogel-based electronics achieves rapid advances, overcoming the drawbacks of rigid and unportable thermocouples. However, an open question is whether and how the thermosensitive hydrogel designing can prevent mechanical mismatching between devices and skin-tissues and reduces interfacial failure. Herein, a versatile hydrogel-based thermistor epidermal sensor (HTES) paradigm is engineered consisting of thermosensitive and self-adhesive function layer (PEST) in tandem with a surface spraying Ag interdigital electrode. Leveraging the advantage of catechol chemistry inspired tannic acid-coated cellulose nanocrystals, the resultant PEST achieves the adhesion-cohesion equilibrium along with superior thermosensitivity. The assembled HTES thereby yields unprecedented features of superior thermosensitivity (TCR = 1.43% °C⁻¹), exceptional mechanical integrity (hammering 200 cycles, current variation <9%), impressive interfacial compatibility (adhesion strength, 25 kPa), and environmental stability (thermosensation retention of 98% over 5 days). By in-situ microstructure observation, the unique geometrical synchronization of HTES with arbitrary curvilinear surfaces (e.g., sphere, cone, and saddle) stemming from elastic dissipation and discrete rupture of the adhesive fibrillar bridges is validated, affording competitive advantages than that of the state-of-the-art thermistor electronics for alleviating the interfacial deterioration, which dramatically inspires advanced HTES design strategies and paves the way for commercialization of attachable thermistor electronics.     

Optimized Ti?O Subcompounds and Elastic Expanded MXene Interlayers Boost Quick Sodium Storage Performance

To develop quick-charge sodium-ion battery, it is significant to optimize insertion-type anode to afford fast Na⁺ diffusion rate and excellent electron conductivity. First-principles calculations reveal the Ti O subcompound superiority for Na⁺ diffusion following Ti(II) O > Ti(III) O > Ti(IV) O. Hence, in situ growth of amorphous Ti O subcompounds with rich oxygen defects based on Ti₃C₂T_x-MXene is developed. Meanwhile, the composite presents expanded MXene interlayer spacing and much enhanced conductivity. The synergistic effect of enhanced electron/ion conduction gives a high capacity of 107 mAh g⁻¹ at 50 A g⁻¹, which gives 50% and 150% increasements compared with one counterpart without valence adjustment and another one without MXene expansion. It only needs 20 s (at 30 A g⁻¹) to complete the discharge/charge process and obtains a capacity of 144.5 mAh g⁻¹, which also shows a long-term cycling stability at quick-charge mode (121 mAh g⁻¹ after 10000 cycles at 10 A g⁻¹). The enhanced performance comes from fast electron transfer among Ti O subcompounds contributed by rich-defect amorphous TiO_2–x, and a reversible change of elastic MXene with interlayer spacing between 1.4 and 1.9 nm during Na⁺ insertion/extraction process. This study provides a feasible route to boost the kinetics and develop quick-charge sodium-ion battery.     

Conjugated polyelectrolyte-assisted vacuum-free transfer-printing of silver nanowire network for top electrode of polymer light-emitting diodes

We report vacuum-free transfer-printing of silver nanowire (AgNW) network film as a top electrode of polymer light-emitting diodes (PLEDs) using conjugated polyelectrolyte (CPE) interfacial layer. AgNW network is delivered from a donor substrate to the desired area of the devices through an elastomeric polydimethylsiloxane (PDMS) mold stamp. The application of CPE layer with an appropriate thickness on the surface of AgNW and light-emitting polymer (LEP) films provides not only good adhesion between the organic and metal layers but also lowering of the work-function of AgNW electrode for better electron injection at LEP/AgNW interface. PLEDs with laminated AgNW top electrode at the optimized condition show the maximum device efficiencies of 3.81 cd A⁻¹ and 2.99 lm W⁻¹ at 4 V, which are comparable to those of PLEDs with Al cathode.     

Solar-Driven Interfacial Evaporation Accelerated Electrocatalytic Water Splitting on 2D Perovskite Oxide/MXene Heterostructure

The rational design of economic and high-performance electrocatalytic water-splitting systems is of great significance for energy and environmental sustainability. Developing a sustainable energy conversion-assisted electrocatalytic process provides a promising novel approach to effectively boost its performance. Herein, a self-sustained water-splitting system originated from the heterostructure of perovskite oxide with 2D Ti₃C₂T_x MXene on Ni foam (La_1-xSr_xCoO₃/Ti₃C₂T_x MXene/Ni) that shows high activity for solar-powered water evaporation and simultaneous electrocatalytic water splitting is presented. The all-in-one interfacial electrocatalyst exhibits highly improved oxygen evolution reaction (OER) performance with a low overpotential of 279 mV at 10 mA cm⁻² and a small Tafel slope of 74.3 mV dec⁻¹, superior to previously reported perovskite oxide-based electrocatalysts. Density functional theory calculations reveal that the integration of La_0.9Sr_0.1CoO₃ with Ti₃C₂T_x MXene can lower the energy barrier for the electron transfer and decrease the OER overpotential, while COMSOL simulations unveil that interfacial solar evaporation could induce OH⁻ enrichment near the catalyst surfaces and enhance the convection flow above the catalysts to remove the generated gas, remarkably accelerating the kinetics of electrocatalytic water splitting.     

Block Copolymer-Based Supramolecular Ionogels for Accurate On-Skin Motion Monitoring

Interest in wearable and stretchable on-skin motion sensors has grown rapidly in recent years. To expand their applicability, the sensing element must accurately detect external stimuli; however, weak adhesiveness of the sensor to a target object has been a major challenge in developing such practical and versatile devices. In this study, freestanding, stretchable, and self-adhesive ionogel conductors are demonstrated which are composed of an associating polymer network and ionic liquid that enable conformal contact between the sensor and skin even during dynamic movement. The network of ionogel is formed by noncovalent association of two diblock copolymers, where phase-separated micellar clusters are interconnected via hydrogen bonds between corona blocks. The resulting ionogels exhibit superior adhesive characteristics, including a very high lift-off force of 93.3 N m⁻¹, as well as excellent elasticity (strain at break ≈ 720%), toughness ( ≈ 2479 kJ m⁻³), thermal stability ( ≈ 150  ° C), and high ionic conductivity ( ≈ 17.8 mS cm⁻¹ at 150  ° C). These adhesive ionogels are successfully applied to stretchable on-skin strain sensors as sensing elements. The resulting devices accurately monitor the movement of body parts such as the wrist, finger, ankle, and neck while maintaining intimate contact with the skin, which was not previously possible with conventional non-adhesive ionogels.     

Redox-Active Polymer Integrated with MXene for Ultra-Stable and Fast Aqueous Proton Storage

Proton is a charge carrier with the smallest ionic size and quickest kinetics, making aqueous proton batteries (APBs), a promising technology for safe and profitable energy storage systems. Despite being potential electrode materials, organic compounds have not yet been fully investigated in terms of proton storage properties and APB applications due to their low capacity and unstable cycle life in aqueous electrolytes. Herein, a novel redox-active polymer (PDPZ) with diquinoxalino-phenazine as the structural unit has been designed, which is further integrated with MXene nanosheets to construct a flexible PDPZ@MXene electrode material with a rapid and ultra-stable proton storage behavior. In-operando monitoring techniques, i.e., in situ Raman and in situ FTIR, demonstrate the highly reversible redox reaction between CN and C N/N H bonds in electro-active PDPZ molecule with the strong proton absorption ability. Theoretical calculation further proves the electron transfer from MXene to PDPZ promotes the redox reaction of the PDPZ@MXene electrode. As a result, a flexible APB device is developed with a considerable energy density (64.3 mWh cm⁻³), a supercapacitor-level power density (6000 mW cm⁻³), and a record lifespan with ≈98.2% capacity retention over 10 000 cycles, revealing its potential applications in satisfying the various requirements of energy storage systems.