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To optimize the cycle life and rate performance of lithium‐ion batteries (LIBs), ultra‐fine Fe2O3 nanowires with a diameter of approximately 2 nm uniformly anchored on a cross‐linked graphene ribbon network are fabricated. The unique three‐dimensional structure can effectively improve the electrical conductivity and facilitate ion diffusion, especially cross‐plane diffusion. Moreover, Fe2O3 nanowires on graphene ribbons (Fe2O3/GR) are easily accessible for lithium ions compared with the traditional graphene sheets (Fe2O3/GS). In addition, the well‐developed elastic network can not only undergo the drastic volume expansion during repetitive cycling, but also protect the bulk electrode from further pulverization. As a result, the Fe2O3/GR hybrid exhibits high rate and long cycle life Li storage performance (632 mAh g−1 at 5 A g−1, and 471 mAh g−1 capacity maintained even after 3000 cycles). Especially at high mass loading (≈4 mg cm−2), the Fe2O3/GR can still deliver higher reversible capacity (223 mAh g−1 even at 2 A g−1) compared with the Fe2O3/GS (37 mAh g−1) for LIBs. Winning ribbon: Graphene ribbon networks can effectively improve electron/ion transfer to enhance the battery performance of hybrids, especially at high mass loading. Ultra‐fine Fe2O3 nanowires uniformly anchored on interconnected graphene ribbon networks are successfully synthesized, and exhibit high rate and long cycle life performance. [ABSTRACT FROM AUTHOR]

The development of stable electrode materials for sodium‐ion batteries (NIBs) with excellent rate capacity, high volumetric/gravimetric capacity, and ultralong‐term cycling stability still remains a challenge. Herein, a novel strategy for the synthesis of edge‐nitrogen‐rich carbon dots pillared graphene blocks (N‐CDGB) through self‐polymerization of aniline into graphene oxide blocks, and subsequent carbonization is developed. Due to high bulk density (1.5 g cm−3) and integrated lamellar structure with large edge‐interlayer spacing (4.2 Å) pillared by nitrogen‐doped carbon dots (95% edge‐nitrogen content), the dense N‐CDGB shows robust structural stability, fast ion/electron transfer pathways, and more active sites for sodium storage. As a result, the N‐CDGB electrode exhibits ultrahigh reversible volumetric and gravimetric capacities (780 mAh cm−3/520 mAh g−1 at 0.02 A g−1) far exceeding those of graphene (108 mAh cm−3/290 mAh g−1) and hard carbon (297 mAh cm−3/311 mAh g−1), excellent rate capability (118 mAh g−1/177 mAh cm−3 at 10 A g−1), and superior cycling stability up to 10 000 cycles with almost no capacity loss at 10 A g−1. This work signifies the superiority of densely pillared structure in the future development of NIBs with high volumetric/gravimetric capacity and ultralong‐term cycling stability. Edge‐nitrogen‐rich carbon dots pillared graphene blocks synthesized from natural graphite exhibit ultrahigh volumetric/gravimetric capacities (780 mAh cm−3/520 mAh g−1 at 0.02 A g−1), excellent rate performance, and ultralong cycle life. [ABSTRACT FROM AUTHOR]

Abstract Nickel hexacyanoferrate (NiHCF) with rigid open framework is promising for energy storage devices, yet still suffer from inferior conductivity and low energy density. Herein, NiHCF supported on diallyldimethylammonium chloride (PDDA) modified graphene (PRGO-NiHCF) was successfully synthesized via a facile co-precipitation method. The size of NiHCF nanoparticals decreased from 50 nm to 20 nm with the introduction of PDDA-induced reduced graphene oxide. The unique structure can not only reversibly accommodate hydrated alkali cations with 3D open-framework, but also facilitate the electrons transportation through the graphene basal plane. Consequently, the as-obtained PRGO-NiHCF exhibits higher specific capacitances of 294 F g−1 at 2 mV s−1 compared to pure NiHCF (176 F g−1). Moreover, under the combination of PRGO-NiHCF positive electrode and the interconnected sandwiched graphene carbon (SGC) negative electrode, the as-assembled asymmetric supercapacitor delivers a wide operation potential of 1.8 V and a high energy density of 25.4 Wh kg−1. Highlights • The PRGO-NiHCF possesses many mesopores and small nanoparticals for efficient charge storage. • The specific capacitance of PRGO-NiHCF is 294 F g−1 at 2 mV s−1, higher than that of pure NiHCF (176 F g−1). • The SGC//PRGO-NiHCF asymmetric supercapacitor delivers a high energy density of 25.4 Wh kg−1. [ABSTRACT FROM AUTHOR]

[Display omitted] • Unique graphene ribbon and Ni wire lead robust electron and ion transport. • Ultrahigh length capacitance of 73.8 mF·cm−1. • Excellent weldability of our devices. Carbon-based fiber supercapacitors hold great potential in portable electronics. However, those fiber-based electrodes often suffer from low length capacitance and poor rate performance due to low electrical conductivity and sluggish ion diffusion kinetics. And the poor weldability hinders the design of complex circuits. Herein, we report a simple strategy to prepare weldable and flexible graphene ribbon@Ni fiber (GR-Ni-5) with fast ion/electron transfer capabilities for fiber-shaped supercapacitors via the immersion-drying process and followed by thermal treatment. As a result, the GR-Ni-5 exhibits an ultrahigh length capacitance of 73.8 mF·cm−1 at 2 mV·s−1, remarkable rate performance (26.8 mF·cm−1, 200 mV·s−1), and ultrahigh capacitance retention of 80% with the length of the electrode from 1.0 to 10.0 cm. Moreover, the assembled all-solid-state symmetric supercapacitor using GR-Ni-5 fibers as the electrodes and polyvinyl alcohol (PVA)/KOH gel as electrolyte can deliver remarkable electrochemistry properties, as well as good flexibility, and remarkable weldability which are beneficial for miniaturization and application. [ABSTRACT FROM AUTHOR]