Limited by 2D geometric morphology and low bulk packing density, developing graphene‐based flexible/compressible supercapacitors with high specific capacitances (gravimetric/volumetric/areal), especially at high rates, is an outstanding challenge. Here, a strategy for the synthesis of free‐standing graphene ribbon films (GRFs) for high‐performance flexible and compressible supercapacitors through blade‐coating of interconnected graphene oxide ribbons and a subsequent thermal treatment process is reported. With an ultrahigh mass loading of 21 mg cm−2, large ion‐accessible surface area, efficient electron and ion transport pathways as well as high packing density, the compressed multilayer‐folded GRF films (F‐GRF) exhibit ultrahigh areal capacitance of 6.7 F cm−2 at 5 mA cm−2, high gravimetric/volumetric capacitances (318 F g−1, 293 F cm−3), and high rate performance (3.9 F cm−2 at 105 mA cm−2), as well as excellent cycling stability (109% of capacitance retention after 40 000 cycles). Furthermore, the assembled F‐GRF symmetric supercapacitor with compressible and flexible characteristics, can deliver an ultrahigh areal energy density of 0.52 mWh cm−2 in aqueous electrolyte, almost two times higher than the values obtained from symmetric supercapacitors with comparable dimensions.

With the development of economy and society, the energy storage devices possessing both high energy and power densities are urgently desired to meet the requirement of fast-charging electronics, electric vehicles, and smart grids. [1] Although rechargeable batteries have been widely used due to its high energy density, the sluggish kinetics restricts its power density. [2] On the other hand, supercapacitors show high power density and good cycle stability but a rather low energy density. [3] Recently, the hybrid capacitors combining the battery-type anodes and the capacitor-type cathodes have attracted much attention for achieving both high energy and power densities. [4] Compared with lithium ion capacitors, sodium ion capacitors (SICs) are more attractive due to the low cost and source abundance of sodium. [5] However, most anode materials suffer from poor electrochemical kinetics because of the larger ion diameter of Na + than Li +. [6] Therefore, developing appropriate electrode materials to meet the high-capacity and high-power requirements of SICs is urgently needed. Molybdenum disulfide (MoS 2), a typical 2D transition metal dichalcogenides stacked by van der Waals force, has attracted great attention for electrochemical sodium storage due to its high capacity of 670 mAh g −1. [7] However, its high theoretical capacity is hardly realized because of the low conductivity and limited interlayer ion transport kinetics. [8] More seriously, these intrinsic drawbacks result in poor rate performance and cycle stability, further restricting its practical application for highpower devices. [9] For metal compounds (e.g., metal oxides and metal sulfides) as electrode materials for ion batteries, the most common route to solve the conductive issue is compositing with conductive carbon scaffolds such as carbon nanotube, [10] graphene, [11] and carbon fiber. [12] Specially, the strong interfacial interaction between two phases has been proven to play important roles for improving the electrochemical kinetics and cycle stability. [13] To form the strong interaction, the carbon scaffolds are usually functionalized with oxygen-containing functional groups to improve the surface compatibility, simultaneously resulting Molybdenum disulfide (MoS 2) holds great potential for sodium storage due to its high theoretical capacity of 670 mAh g −1. However, its theoretical capacity is hardly realized because of low conductivity, sluggish electrochemical kinetics, and unsatisfied structural stability. Herein, a polyaniline-mediated interfacial engineering strategy for the growth of interlayer-expanded MoS 2 nanoflowers on N-doped graphene "land" (E-MoS 2 /NG) using Mo 7 O 24 6− anions adsorbed on positively charged polyaniline as the "seeds" is reported. The strong interfacial interaction between MoS 2 and graphene through MoN bonds as well as ultrathin interlayer-expanded MoS 2 can significantly improve the electrochemical kinetics and structural stability. As a result, E-MoS 2 /NG with a high MoS 2 content of 90 wt% shows a high ca...

electric vehicles. [1,2] However, the further scaled application of commercial LIBs encounters a "bottleneck": the overall energy density is approaching the ceiling due to the restriction of theoretical specific capacity of insertion-type oxide cathodes (≈250 mAh g −1 ) and graphite anodes (372 mAh −1 ). In order to satisfy the increasing demand for higher energy densities particularly under the extended application such as unmanned aerial vehicles, cargo aircraft, electric vehicles, and the exploration of novel storage system is of great significance. [3] Sulfur is earthabundant, low-cost, and environment friendly. More inspiring, lithium-sulfur batteries (LSBs) based on sulfur cathodes exhibit much higher theoretical specific capacity (1675 mAh g −1 ) through the multielectron redox reaction process, showing great potential for high-performance energy storage devices. [4] Despite the promising prospects, the practical application of LSBs is still impeded by several challenges, such as electrical insulation of sulfur and discharge products (Li 2 S/Li 2 S 2 ), severe shuttle effect of long-chain polysulfides (LiPSs, Li 2 S n , 4 ≤ n ≤ 8), low sulfur utilization, and large volume expansion (≈80%), which are critically fatal for the cycle stability and power density. [5] In the last decades, tremendous Lithium-sulfur batteries (LSBs) are severely impeded by their poor cycling stability and low sulfur utilization due to the inevitable polysulfide shuttle effect and sluggish reaction kinetics. This work reports a Mott-Schottky RGO-PANI/MoS 2 (RPM) heterogeneous layer modified separator for commercialsulfur-based LSBs through the vertical growth of molybdenum sulfide (MoS 2 ) arrays on the polyaniline (PANI) in situ reduced graphene oxide (RGO). Due to the synergistic effects of the "reservoir" constructed by MoS 2 and RGO-PANI, strong absorbability, high conductivity, and electrocatalytic activity, RPM exhibits a successive "trapping-interception-conversion" behavior toward lithium polysulfides. As a result, the LSBs assembled using a commercialsulfur as the cathode and RPM as modified layer exhibit high sulfur utilization (3.8 times higher than that of the unmodified separator at 5 C), excellent rate performance (553 mAh g −1 at 10 C), and outstanding high-rate cycle stability (524 mAh g −1 after 700 cycles at 5 C). Moreover, even at a high sulfur loading of 5.4 mg cm −2 , a favorable areal capacity of 3.8 mAh cm −2 is still maintained after 80 cycles. Theoretical calculations elucidate that such a systematic strategy can effectively suppress the shuttling effect and boost the catalytic conversion of intercepted polysulfides. This work may provide a feasible strategy to promote the practical application of commercial-sulfur-based LSBs.

High surface area, good conductivity, and high mechanical strength are important for carbon nanofiber fabrics (CNFs) as high-performance supercapacitor electrodes. However, it remains a big challenge because of the trade-off between the strong and continuous conductive network and a well-developed porous structure. Herein, we report a simple strategy to integrate these properties into the electrospun CNFs by adding graphene quantum dots (GQDs). The uniformly embedded GQDs play a crucial bifunctional role in constructing an entire reinforcing phase and conductive network. Compared with the pure CNF, the GQD-reinforced activated CNF exhibits a greatly enlarged surface area from 140 to 2032 m2 g–1 as well as a significantly improved conductivity and strength of 5.5 and 2.5 times, respectively. The mechanism of the robust reinforcing effect is deeply investigated. As a freestanding supercapacitor electrode, the fabric performs a high capacitance of 335 F g–1 at 1 A g–1 and extremely high capacitance retentions of 77% at 100 A g–1 and 45% at 500 A g–1. Importantly, the symmetric device can be charged to 80% capacitance within only 2.2 s, showing great potential for high-power startup supplies.

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