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An alloying-type metal foil serves as an integrated anode that is distinct from the prevalent powder-casting production of lithium ion batteries (LIBs) and emerging lithium metal batteries (LMBs), and also its energy density and processing technology can be profoundly developed. However, besides their apparent intriguing advantages of a high specific capacity, electrical conductivity, and the ease of formation, metal foil anodes suffer from slow lithiation kinetics, a trade-off between specific capacity and cycle life, and a low initial Coulombic efficiency (ICE) owing to their multi-scaled structural geometry, huge volume change, and induced interfacial issues during the alloying process. In this review, we attempt to present a comprehensive overview on the recent research progress with respect to alloying-type metal foil anodes toward high-energy-density and low-cost LIBs. The failure mechanism of metal foil anodes during lithiation/delithiation and existing challenges are also summarized. Subsequently, the structural design and interface engineering strategies that have witnessed significant achievements are highlighted, which can promote the practical development of LIBs, including artificial SEI, alloying, structural design, and grain refinement. Furthermore, scientific perspectives are proposed to further improve the overall performance and decouple the complex mechanisms in terms of interdisciplinary fields of electrochemistry, metallic materials science, mechanics, and interfacial science, demonstrating that metal foil anode-based LIBs require more research efforts.

Thermally conductive and electrically insulating thermal interface materials (TIMs) are highly desired for electronic cooling. To improve heat transfer efficiency, thermally conductive fillers with a high loading content have been incorporated into the polymer-based TIMs. However, this is usually at the expense of the interfacial thermal resistance reduction and reliability. In this study, vertically aligned boron nitride nanosheet films (VBNFs) have been prepared by a scalable microfluidic spinning process and template-assisted chemical vapor deposition conversion method. A further high-temperature annealing was applied to achieve high crystallinity. VBNFs have been applied as fillers to fabricate TIMs and achieve a superior through-plane thermal conductivity of 6.4 W m–1K–1and low modulus of 2.2 MPa at low BN loading of 9.85 vol %, benefitting from the well-aligned vertical sheet structure and high crystallinity. In addition, the fabricated TIMs present high-volume resistivity and breakdown strength, satisfying the electrical insulation demands. The high thermal conductivity and low modulus contribute an outstanding cooling performance to the TIMs in the heat dissipation application for high-power LEDs. This template-assisted conversion technology for the fabrication of orientated BN nanosheets structure and the prepared high-performance TIMs pave the way for efficient thermal management of high-power electronics.

Two-dimensional (2D) nanosheets have been assembled into various macroscopic structures for wide engineering applications. To fully explore their exceptional thermal, mechanical, and electrical properties, 2D nanosheets must be aligned into highly ordered structures due to their strong structural anisotropy. Structures stacked layer by layer such as films and fibers have been readily assembled from 2D nanosheets due to their planar geometry. However, scalable manufacturing of macroscopic structures with vertically aligned 2D nanosheets remains challenging, given their large lateral size with a thickness of only a few nanometers. Herein, we report a scalable and efficient microfluidics-enabled sheet-aligning process to assemble 2D nanosheets into a large-area film with a highly ordered vertical alignment. By applying microchannels with a high aspect ratio, 2D nanosheets were well aligned vertically under strong channel size confinement and high flow shear stress. A vertically aligned graphene sheet film was obtained and applied to effectively improve the heat transfer of thermal interfacial materials (TIMs). Superior through-plane thermal conductivity of 82.7 W m−1K−1at a low graphene content of 11.8 vol% was measured for vertically aligned TIMs. Thus, they demonstrate exceptional thermal management performance for switching power supplies with high reliability.

Low-power electronics are urgently needed for various emerging technologies, e.g., actuators as signal transducers and executors. Collecting energy from ubiquitous low-grade heat sources (T< 100 °C) as an uninterrupted power supply for low-power electronics is highly desirable. However, the majority of energy-harvesting systems are not capable of collecting low-grade heat energy in an efficient and constant manner. Limited by materials and driving mode, fabrications of low-power and energy-efficient actuators are still challenging. Here, highly thermally conductive bimorph structures based on graphene/poly(dimethylsiloxane) (PDMS) structures have been fabricated as low-grade heat energy harvesters and energy-efficient actuators. Regular temperature fluctuations on bimorph structures can be controlled by nonequilibrium heat transfer, leading to stable and self-sustained thermomechanical cycles. By coupling ferroelectric poly(vinylidene fluoride) with bimorph structures, uninterrupted thermomechanoelectrical energy conversion has been achieved from the low-grade heat source. Utilizing the rapid thermal transport capability, multifinger soft grippers are assembled with bimorph actuators, demonstrating fast response, large displacement, and adaptive grip when driven by low-temperature heaters.

Aqueous zinc-ion batteries (ZIBs) are regarded as a promising candidate for ultrafast charge storage owing to the high ionic conductivity of aqueous electrolytes and high theoretical capacity of zinc metal anodes. However, the strong electrostatic interaction between high-charge-density zinc ions and host materials generally leads to sluggish ion-transport kinetics and structural collapse of rigid cathode materials during the charge/discharge process, so searching for suitable cathode materials for ultrafast and long-term stable ZIBs remains a great challenge. Herein, flexible electron-rich ion channels enabling fast-charging and stable aqueous ZIBs have been demonstrated. Because of the nitrogen-rich conjugated structure of organic phenazine (PNZ) molecules, electron-rich ion channels are formed with the C═N redox centers situated on the channel surface, where zinc ions can transport rapidly and react with active moieties directly. Meanwhile, the π-conjugated systems and inherent flexibility of PNZ molecules can accommodate rapid strain changes and maintain their structural stability during zinc-ion intercalation/deintercalation. Consequently, they exhibit a high capacity of 94.2 mAh g–1at an ultrahigh rate of 700C (208.6 A g–1) and an ultralong life over 100,000 cycles at 100C, which are superior to those of previously reported aqueous ZIBs. Our work presents a new way for developing ultrafast and ultrastable aqueous ZIBs.

The electron-rich characteristic and low work function endow electrides with excellent performance in (opto)electronics and catalytic applications; these two features are closely related to the structural topology, constituents, and valence electron concentration of electrides. However, the synthesized electrides, especially two-dimensional (2D) electrides, are limited to specific structural prototypes and anionic p-block elements. Here we synthesize and identify a distinct 2D electride of BaCu with delocalized anionic electrons confined to the interlayer spaces of the BaCu framework. The bonding between Cu and Ba atoms exhibits ionic characteristics, and the adjacent Cu anions form a planar honeycomb structure with metallic Cu–Cu bonding. The negatively charged Cu ions are revealed by the theoretical calculations and experimental X-ray absorption near-edge structure. Physical property measurements reveal that BaCu electride has a high electronic conductivity (ρ = 3.20 μΩ cm) and a low work function (2.5 eV), attributed to the metallic Cu–Cu bonding and delocalized anionic electrons. In contrast to typical ionic 2D electrides with p-block anions, density functional theory calculations find that the orbital hybridization between the delocalized anionic electrons and BaCu framework leads to unique isotropic physical properties, such as mechanical properties, and work function. The freestanding BaCu monolayer with half-metal conductivity exhibits low exfoliation energy (0.84 J/m2) and high mechanical/thermal stability, suggesting the potential to achieve low-dimensional BaCu from the bulk. Our results expand the space for the structure and attributes of 2D electrides, facilitating the discovery and potential application of novel 2D electrides with transition metal anions.

Performance degradation of lithium/sodium-ion capacitors (LICs/SICs) mainly originates from anode pulverization, particularly the alloying and conversion types, and has spurred research for alternatives with an insertion mechanism. Three-dimensional (3D) topotactic host materials remain much unexplored compared to two-dimensional (2D) ones (graphite, etc.). Herein, vanadium monophosphide (VP) is designed as a 3D topotactic host anode. Ex situelectrochemical characterizations reveal that there are no phase changes during (de)intercalation, which follows the topotactic intercalation mechanism. Computational simulations also confirm the metallic feature and topotactic structure of VP with a spacious interstitial position for the accommodation of guest species. To boost the electrochemical performance, carbon nano-onions (CNOs) are coupled with 3D VP. Superior specific capacity and rate capability of VP-CNOs vslithium/sodium can be delivered due to the fast ion diffusion nature. An exceptional capacity retention of above 86% is maintained after 20 000 cycles, benefitting from the topotactic intercalation process. The optimized LICs/SICs exhibit high energy/power densities and an ultrastable lifespan of 20 000 cycles, which outperform most of the state-of-the-art LICs and SICs, demonstrating the potential of VP-CNOs as insertion anodes. This exploration would draw attention with regard to insertion anodes with 3D topotactic host topology and provide new insights into anode selection for LICs/SICs.

Transparent and flexible supercapacitors (TFSCs) are viable power sources for next-generation wearable electronics. The ingenious design of the transparent electrode determines the performance of TFSCs. A percolating film of a pillared graphene layer integrated with a silver nanowire network as the transparent electrode was prepared, by which TFSC devices exhibit a significantly improved performance contrastively. Under the condition of the same transmittance, about 27–72% improvement in the areal capacitance can be achieved. On the one hand, the pillars of carbon nanotube (CNT) were distributed in the graphene layer uniformly, enlarging the inner distance of adjacent graphene layers and providing an open structure for extra ion transport and storage of TFSCs. On the other hand, the introduced CNT could facilitate the electron transport at the direction perpendicular to the graphene basal plane, enhancing the electronic conductivity of the graphene layer. More importantly, the formed percolating film ensures an efficient transport of electron along with the silver nanowire when it encounters the obstacle within the graphene layer, resulting in a highly conductive electrode. The TFSC device with a good compatibility indicates a reliable practicability, which provides a facile route toward the design of high-performance TFSCs.

LiSn2(PO4)3anion was used to partially substitute for VO43–in the Nasicon compound of LiSn2(PO4)3viaa sol-gel method. XRD analysis revealed that the LiSn2(PO4)3-substituted samples did not have a single LiSn2(PO4)3phase, and some secondary phases like SnO2and SnP2O7 appeared. Introduction of the LiSn2(PO4)3anion did not prevent the LiSn2(PO4)3compound from decomposing during the initial lithiation; however the LiSn2(PO4)3anion substitution remarkably enhanced the rate capability and cycling performance of the products because they reduced the charge transfer impedance, increased the lithium ion diffusion, and strengthened the role of the Li3VO4matrix due to the precipitation of the Li3VO4phase. Of the substituted samples, the sample with a nominal composition of LiSn2(PO4)2.5(VO4)0.5delivered a capacity of 449.2 mA·h/g at a rate of 0.25 C after 25 cycles and 373.8 mA·h/g at 2 C rate. Those values surpassed some previous reports on LiSn2(PO4)3and the LiSn2(PO4)3/C composites. Accordingly, the partial substitution of phosphorus by vanadium in LiSn2(PO4)3is a feasible technique to remarkably improve its electrochemical properties.

Sodium ion capacitors (SICs) represent a promising alternative of energy storage device with high energy/power densities as well as long life span. Exploration of novel anode materials with typically high rate performance is a shortcut to boost the performance of SICs. Here, we present a WSe2/reduced graphene oxide (rGO) nanocomposite synthesized by a home-made chemical vapor deposition (CVD) method. WSe2 nanoparticle is deposited uniformly at the surface of rGO nanosheets. The unique structure endows the composite with outstanding electrochemical properties. The specific capacity of 133.3 mAh g[?]1 at an ultrahigh current density of 60 A g[?]1 can be delivered. The sodium ion storage kinetics was investigated, exhibiting very high ratio of capacitive contribution during the sodium ion reaction process. The SICs based on the WSe2/rGO nanocomposite as anode show the maximum energy density of 42.8 W h kg[?]1 and maximum power density of 14.4 kW kg[?]1 as well as the superior cyclic stability, proving the promising of WSe2/rGO anode for SICs application.

The high-energy lithium/sulfur (Li/S) battery has become a very popular topic of research in recent years due to its high theoretical capacity of 1672 mAh/g. However, the polysulfide shuttle effect remains of great concern with a great number of publications dedicated to its mitigation. In this contribution, a three-dimensional (3D) reduced graphene oxide/activated carbon (RGO/AC) film, synthesized by a simple hydrothermal method and convenient mechanical pressing, is sandwiched between the separator and the sulfur-based cathode, acting as a functional interlayer to capture and trap polysulfide species. Consequently, the Li/S cell with this interlayer shows an impressive initial discharge capacity of 1078 mAh/g and a reversible capacity of 655 mAh/g even after 100 cycles. The RGO/AC interlayer impedes the movement of polysulfide while providing unimpeded channels for lithium ion mass transfer. Therefore, the RGO/AC interlayer with a well-designed structure represents strong potential for high-performance Li/S batteries.

High performance composite of nanosized Li4Ti5O12(LTO) and graphene nanosheets was fabricated using a novel atomic layer deposition (ALD) seeded process incorporated with hydrothermal lithiation for the first time. TiO2nanoislands as seeds were anchored on graphene by ALD process, triggering the unique structure formation of subsequent LTO. The synergistic effects of nanosized LTO and graphene endow the composite with a short lithium ion diffusion path and efficiently conductive network for electron and ion transport, boosting the excellent reversible capacity, rate capability, and cyclic stability as anode materials for lithium ion capacitors (LICs). The reversible capacity of 120.8mAhg−1at an extremely high current rate of 100C was achieved successfully, and the electrode can be charged/discharged to about 70% of the theoretical capacity of LTO in 25s. Meanwhile, the composite exhibited excellent cyclic stability of 90% capacity retention at 20C with nearly 100% Coulombic efficiency after 2500 cycles. The sintering treatment after hydrothermal reaction has significant effects on the crystallinity, defect density, microstructure and electrochemical property of the composite, which is also supported by theoretical calculations. The results provide a versatile roadmap for synthesis of high performance LTO based composite and new insights into LICs.

Amorphous TiO2 (a-TiO2) thin films were conformally coated onto the surface of hydroxyl functionalized multi-walled carbon nanotubes (CNTs) using atomic layer deposition (ALD). The electrochemical characteristics of the a-TiO2/CNT nanocomposites were then determined using cyclic voltammetry and galvanostatic charge/discharge curves. The ultrathin TiO2 ALD films displayed high specific capacity and high rate capability. The specific capacities of the a-TiO2/CNT nanocomposites after 50 and 100 TiO2 ALD cycles at 100 mA/g were 220 mAh/g and 240 mAh/g, respectively. For CNTs coated with 100 TiO2 ALD cycles, 88% of the capacity at 100 mA/g could be maintained at 1 A/g. When the voltage window for the a-TiO2/CNT nanocomposites was extended down to 0.5 V versus Li/Li+, the CNTs coated with 50 and 100 TiO2 ALD cycles exhibited specific capacities at 100 mA/g of 275 mAh/g and 312 mAh/g, respectively. These high capacities are higher than the bulk theoretical values and are attributed to additional interfacial charge storage resulting from the high surface area of the a-TiO2/CNT nanocomposites. Free-standing TiO2-CNT electrodes were also fabricated and displayed excellent capacity and rate capability. These results demonstrate that TiO2 ALD on high surface area CNT substrates can provide high power and high capacity anodes for lithium ion batteries.

Organic phase change materials (PCMs) have been utilized as latent heat energy storage and release media for effective thermal management. A major challenge exists for organic PCMs in which their low thermal conductivity leads to a slow transient temperature response and reduced heat transfer efficiency. In this work, 2D thermally annealed defect-free graphene sheets (GSs) can be obtained upon high temperature annealing in removing defects and oxygen functional groups. As a result of greatly reduced phonon scattering centers for thermal transport, the incorporation of ultralight weight and defect free graphene applied as nanoscale additives into a phase change composite (PCC) drastically improve thermal conductivity and meanwhile minimize the reduction of heat of fusion. A high thermal conductivity of the defect-free graphene-PCC can be achieved up to 3.55 W/(m K) at a 10 wt % graphene loading. This represents an enhancement of over 600% as compared to pristine graphene-PCC without annealing at a comparable loading, and a 16-fold enhancement than the pure PCM (1-octadecanol). The defect-free graphene-PCC displays rapid temperature response and superior heat transfer capability as compared to the pristine graphene-PCC or pure PCM, enabling transformational thermal energy storage and management.

Amorphous TiO2thin films were conformally coated onto the surface of both graphene (G) and multiwalled carbon nanotube (CNT) samples using atomic layer deposition (ALD). An ultrathin Al2O3adhesion layer was employed to obtain the conformal TiO2ALD films. Using 1 M KOH as the electrolyte, the electrochemical characteristics of TiO2ALD films grown using 25 and 50 TiO2ALD cycles were then determined using cyclic voltammetry, galvanostatic charge/discharge curves, and electrochemical impedance spectroscopy. Because the TiO2ALD films were ultrathin, the poor electrical conductivity and low ionic diffusivity of TiO2did not limit the ability of the TiO2ALD films to display high specific capacitance. The specific capacitances of the TiO2ALD-coated G and CNT samples after 50 TiO2ALD cycles were 97.5 and 135 F/g, respectively, at 1 A/g. The pseudocapacitance of the TiO2ALD films greatly exceeded the electric double layer capacitance of the uncoated G and CNT samples. The galvanostatic charge/discharge experiments also revealed that the charge storage was dependent on the thickness of the TiO2ALD film. This observation argues that the pseudocapacitance is derived largely from the TiO2bulk and is not limited to the TiO2surface. The molar ratio of stored charge to TiO2was estimated to be in the range of 0.03–0.08 (mol stored charge/mol TiO2) for the various TiO2ALD-coated G and CNT samples. An optimized asymmetric cell was also developed based on TiO2ALD-coated CNT as the positive electrode and uncoated CNT as the negative electrode. This energy storage device could be reversibly operated over a wide voltage range of 0–1.5 V in the aqueous 1 M KOH electrolyte. An energy density of 4.47 W·h/kg was achieved on the basis of the total weight of both electrodes. This energy density was ∼4 times higher than the symmetric CNT cell. The TiO2ALD-coated G and CNT electrodes and the asymmetric cell based on the TiO2ALD-coated electrode exhibited excellent stability over >1000 cycles. The results of this study demonstrate that metal oxide ALD on high surface area conducting carbon substrates can be used to fabricate high energy storage supercapacitors.

An ultrathin gold island film is developed showing efficient temperature sensing when maintaining at certain duration and may be a potential candidate as a temperature marker. The developed gold thin film is based on the energy minimization principle, in which unstable ultrathin films experience morphological instability and self-organization upon thermal dewetting, providing the “finger print” for recording the temperature and duration of the thermal event based on their variation of characteristic optical properties. As compared with other temperature sensing mechanisms and nanostructures, the ultrathin gold film displays an irreversible variation that may be employed ex-situ for extreme conditions in which in situ measurements of the thermal history may not be feasible. A high sensitivity is possible for temperature sensing even at temperatures as low as 100 °C when the time is fixed due to an efficient dewetting process at the nanoscale. This Au-based nanostructure allows fast readout of temperature by simply measuring the surface plasmon absorption. The thermal model was developed based on the correlation among the optical properties, morphological evolution, and the dewetting dynamics and validated with experimental data with accurate determination of temperature within an uncertainty of 4%. The thickness-dependent dewetting behavior further opens up the possibility for designing various nanostructures with controllable sensitivities by simple manipulation of the film thickness and thus dewetting dynamics.

Ultrathin gold island films on transparent substrates display a characteristic surface plasmon (SP) absorption band in which the peak position and full width at half-maximum (fwhm) are highly sensitive to the film morphology. In the present study, we investigated the temperature dependence of morphological evolution and the corresponding unique surface plasmon resonance (SPR) properties variation of the ultrathin gold island films (5 nm nominal thickness) upon rapid thermal annealing for 180 s at different temperatures ranging from 100 to 700 °C. The morphological evolution of the ultrathin gold film upon the thermal annealing-induced dewetting was studied using scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the optical properties variation was characterized by a transmission UV–vis-NIR spectroscopy. A strong temperature dependence of morphological evolution and optical properties variation as a function of thermal treatment conditions was identified. The blue shift and band narrowing of the SP absorption band can be correlated with various morphological characteristics, e.g., the increased open area fraction of island films, average separation between islands or nanoparticles (NPs) and the decreased aspect ratio (length divided by width) upon increasing thermal treatment temperatures. The temperature dependence of the transmission localized surface plasmon resonance (T-LSPR) may enable a science-based design of optical sensing and dynamic thermal sensors upon the morphological manipulation of ultrathin metallic surface nanostructures by thermal dewetting.

A nano-scaled coating of titanium oxide (TiO2) on graphene (G) has been achieved via a novel atomic layer deposition (ALD) method. As a potential supercapacitor material, the TiO2-G composites exhibited a capacity of 75 F/g and 84 F/g at a scan rate of 10 mV/s for composites grown using 50 and 100 ALD cycles, respectively. The nearly identical Nyquist plots of the TiO2-G composites compared with those of pure graphene demonstrated that the composites possess excellent conductivity for charge transfer and open structures for ion diffusion. In addition, even with 3-4 times additional mass loading (maximum 3.22 mg/cm2), the composites exhibit no obvious degradation with respect to the electrochemical performance. This ALD approach presents a promising route to synthesize advanced graphene-based nanocomposites for supercapacitor applications.

Transparent flexible supercapacitors (TFSCs) are a tantalizing power supplier for future transparent flexible electronics. However, their energy density is far behind a practical level while maintaining high transparency. We report here a transparent flexible potassium-ion microcapacitor, and its high energy density (15.5 μWh cm–2) roots in the battery-supercapacitor hybrid storage mechanism and much enlarged working voltage (3 V), outperforming the state-of-the-art TFSC, which is generally based on an aqueous electrolyte and an asymmetric pseudocapacitive mechanism. From an electrode material perspective, a multidimensional topotactic host composite anode is designed in which the component not only performs energy storage by synchronous and reversible uptake of potassium ions and electrons into its host structure, but also mutually compensates individual weakness in functional and structural aspects, efficiently constructing a three-dimensional potassium-ion diffusion and electron transport system. This conceptual exhibition provides design principles at material and device levels for high-performance TFSCs.

Sodium ion capacitors (SICs) represent a promising alternative of energy storage device with high energy/power densities as well as long life span. Exploration of novel anode materials with typically high rate performance is a shortcut to boost the performance of SICs. Here, we present a WSe2/reduced graphene oxide (rGO) nanocomposite synthesized by a home-made chemical vapor deposition (CVD) method. WSe2nanoparticle is deposited uniformly at the surface of rGO nanosheets. The unique structure endows the composite with outstanding electrochemical properties. The specific capacity of 133.3 mAh g−1at an ultrahigh current density of 60 A g−1can be delivered. The sodium ion storage kinetics was investigated, exhibiting very high ratio of capacitive contribution during the sodium ion reaction process. The SICs based on the WSe2/rGO nanocomposite as anode show the maximum energy density of 42.8 W h kg−1and maximum power density of 14.4 kW kg−1as well as the superior cyclic stability, proving the promising of WSe2/rGO anode for SICs application.

Amorphous TiO2(a-TiO2) thin films were conformally coated onto the surface of hydroxyl functionalized multi-walled carbon nanotubes (CNTs) using atomic layer deposition (ALD). The electrochemical characteristics of the a-TiO2/CNT nanocomposites were then determined using cyclic voltammetry and galvanostatic charge/discharge curves. The ultrathin TiO2ALD films displayed high specific capacity and high rate capability. The specific capacities of the a-TiO2/CNT nanocomposites after 50 and 100 TiO2ALD cycles at 100 mA/g were 220 mAh/g and 240 mAh/g, respectively. For CNTs coated with 100 TiO2ALD cycles, 88% of the capacity at 100 mA/g could be maintained at 1 A/g. When the voltage window for the a-TiO2/CNT nanocomposites was extended down to 0.5 V versus Li/Li+, the CNTs coated with 50 and 100 TiO2ALD cycles exhibited specific capacities at 100 mA/g of 275 mAh/g and 312 mAh/g, respectively. These high capacities are higher than the bulk theoretical values and are attributed to additional interfacial charge storage resulting from the high surface area of the a-TiO2/CNT nanocomposites. Free-standing TiO2-CNT electrodes were also fabricated and displayed excellent capacity and rate capability. These results demonstrate that TiO2ALD on high surface area CNT substrates can provide high power and high capacity anodes for lithium ion batteries.

A nano-scaled coating of titanium oxide (TiO2) on graphene (G) has been achieved via a novel atomic layer deposition (ALD) method. As a potential supercapacitor material, the TiO2-G composites exhibited a capacity of 75 F/g and 84 F/g at a scan rate of 10 mV/s for composites grown using 50 and 100 ALD cycles, respectively. The nearly identical Nyquist plots of the TiO2-G composites compared with those of pure graphene demonstrated that the composites possess excellent conductivity for charge transfer and open structures for ion diffusion. In addition, even with 3-4 times additional mass loading (maximum 3.22 mg/cm2), the composites exhibit no obvious degradation with respect to the electrochemical performance. This ALD approach presents a promising route to synthesize advanced graphene-based nanocomposites for supercapacitor applications.