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An easy and facile hydrothermal method is presented to synthesize hybrid materials of hollow mesoporous Zn0.76Co0.24S nanospheres anchored on reduced graphene oxide (rGO) sheets (Zn0.76Co0.24S@N/S-rGO), in which the obtained Zn0.76Co0.24S nanospheres are composed of numerous nanoparticles. Being evaluated as anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), the Zn0.76Co0.24S@N/S-rGO composites exhibited a high reversible capacity of 804 and 605 mA h g−1 at the current density of 1 A g−1 after 500 cycles for LIBs and SIBs, respectively. The excellent electrochemical performance of Zn0.76Co0.24S@N/S-rGO composites originates from the synergistic effect between hollow Zn0.76Co0.24S nanospheres and reduction graphene, as well as the void spaces between the neighbouring nanoparticles of Zn0.76Co0.24S providing large contact areas with electrolyte and buffer zone to accommodate the volume variation during the cycling process.

Acrylic fiber is one of three important synthetic fibers in the world. The disposal and reuse of large number of waste acrylic fibers from fabric manufacturers or waste recovery is an urgent economic and environmental issue. Here, a porous carbon was derived from waste acrylic fibers via pre-oxidized, carbonization and KOH activation. Furthermore, we adopted melamine as nitrogen source to dope the porous carbon materials. When used as the anode of lithium ion batteries, this nitrogen-doped porous carbon shows high reversible capacity of ca. 1200 mA h g −1 after 50 cycles at 0.1 A g −1 . Reversible capacities of 550 and 370 mA h g −1 are obtained at higher current densities of 1 and 5 A g −1 after 500 cycles, respectively. The outstanding electrochemical performance are a result of its large mesopore volume, high-level N-doping (especially, pyridinic-N), large quantity of edge defects, and three-dimensional hierarchical porous architecture. This paper demonstrates that the reuse of waste industrial acrylic fibers as energy storage materials is a promising method for both energy and environmental fields. [ABSTRACT FROM AUTHOR]

The rational structure design and strong interfacial bonding are crucially desired for high performance zinc oxide (ZnO)/carbon composite electrodes. In this context, micro-nano secondary structure design and strong dopamine coating strategies are adopted for the fabrication of flower-like ZnO/carbon (ZnO@C nanoflowers) composite electrodes. The results show the ZnO@C nanoflowers (2–6 μm) are assembled by hierarchical ZnO nanosheets (∼27 nm) and continuous carbon framework. The micro-nano secondary architecture can facilitate the penetration of electrolyte, shorten lithium ions diffusion length, and hinder the aggregation of the nanosheets. Moreover, the strong chemical interaction between ZnO and coating carbon layer via C-Zn bond improves structure stability as well as the electronic conductivity. As a synergistic result, when evaluated as lithium ion batteries (LIBs) anode, the ZnO@C nanoflower electrodes show high reversible capacity of ca. 1200 mA h g −1 at 0.1 A g −1 after 80 cycles. As well as good long-cycling stability (638 and 420 mA h g −1 at 1 and 5 A g −1 after 500 cycles, respectively) and excellent rate capability. Therefore, this rational design of ZnO@C nanoflowers electrode is a promising anode for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Highlights • Large specific surface area porous carbon. • Biomass-derived nitrogen/oxygen co-doped biomass carbon. • Excellent rate capability and cycle stability performance in sodium ion battery. Abstract Biomass derived porous carbons are economic and attractive materials for anode electrodes in sodium-ion batteries. In this work, a novel porous carbon has been prepared through activation of longan shell, which demonstrates an interconnected hierarchical porosity comprised of macro-, meso- and micro-pores as well with a high specific surface area of 2990 m2 g−1. Benefiting from the unique pore structure and oxygen and nitrogen dual doping, a well-developed ionic and electronic conductivity is achieved. Remarkably, it exhibits an excellent cycling stability with a capacity up to 345.9 mAh g−1 at a current density of 0.1 A g−1, and maintains a capacity of 304.2 mAh g−1 even at a high current density of 5 A g−1 after 1000 cycles as anodes for sodium-ion batteries. These results indicate that the fabricated porous carbon could be a promising electrode material for sodium-ion batteries. The mechanism of such high sodium-ion storage was also discussed with the scan-rate-dependent CV curves to quantify the pseudo-capacitive contribution. [ABSTRACT FROM AUTHOR]

Graphical abstract A simple co-precipitation approach to fabricate the Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron composites has been developed, which significantly improve the structural stability and conductivity of composite materials and exhibit excellent cycling and rate performance for lithium ion batteries. Highlights • A Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron has been prepared. • The capacity is up to 1571.9 mA h g−1 at 0.1 A g−1. • Ni-NiCo 2 O 4 @ZnCo 2 O 4 exhibited excellent rate capability and cycle stability. • Its excellent electrochemical performance came from yolk-shell architecture and the Ni-doping. Abstract Transition-metal oxide materials have gained significant attention as high-performance anode materials for lithium ion batteries. Great advances have been achieved in the development of micro/nanostructured materials with controllable shape and tunable pore size. In this work, a facile co-precipitation approach has been developed to fabricate the Ni-NiCo 2 O 4 @ZnCo 2 O 4 yolk-shell nano-tetrahedron composites, which significantly improve the structural stability and conductivity of the material. The Ni-NiCo 2 O 4 @ZnCo 2 O 4 is proven to exhibit excellent cycling and rate performance for lithium ion batteries, such as the charge capacity of 1571.9 mA h g−1 after 70 cycles at 0.1 A g−1, 1097.5 mA h g−1 after 600 cycles at 1.0 A g−1. This superior electrochemical performance may attribute to the yolk-shell architecture and the Ni-doping. [ABSTRACT FROM AUTHOR]

Multicomponent metal sulfides have been recognized as promising anode materials for lithium/sodium-ion storage given their enticing theoretical capacities. However, the simplification of synthetic processes and the construction of heterogeneous interfaces of multimetal sulfides remain great challenges. Herein, a hierarchical 1T-MoS 2 /carbon nanosheet decorated Co 1– x S/N-doped carbon (Co 1– x S/NC@MoS 2 /C) hollow nanofiber was designed and constructed via a one-pot hydrothermal method using a cobalt-based coordination polymer nanofiber. This nanofiber can transform in-situ into conductive N-doped carbon hollow fibers embedded with active Co 1– x S nanoparticles, enabling the epitaxial growth of MoS 2 nanosheets. Consequently, the Co 1– x S/NC@MoS 2 /C composites achieve exceptional lithium/sodium-ion storage performance. Compared to MoS 2 /C microspheres and Co 1– x S/NC hollow nanofibers alone, the Co 1– x S/NC@MoS 2 /C hollow nanofibers deliver higher discharge capacities (1085.9 mAh g−1 for lithium-ion batteries (LIBs) and 748.5 mAh g−1 for sodium-ion batteries (SIBs) at 100 mA g−1), better capacity retention (910 mAh g−1 for LIBs and 636.5 mAh g−1 for SIBs after 150 cycles at 100 mA g−1), and increased cycling stability (407.2 mAh g−1 after 1000 cycles for SIBs at 1000 mA g−1). Furthermore, the kinetic analysis shows that the lithium/sodium-ion storage processes of the Co 1– x S/NC@MoS 2 /C electrode are mainly controlled by pseudocapacitance behavior. The excellent electrochemical properties can thus be ascribed to the synergy of the MoS 2 /C nanosheets with the enlarged interlayer spacing, good conductivity of the carbon layers, and the Co 1– x S nanoparticles embedded in the hollow nanofibers with extensive reaction sites. [ABSTRACT FROM AUTHOR]

Graphical abstract A simple electrospinning approach has been developed to fabricate the Mo 2 C@C core-shell nanofibers, which significantly improves the structural stability and conductivity, exhibit excellent cycling and rate performance as anode of lithium-ion batteries. Highlights • Hollow Mo 2 C@C core-shell nanofibers have been synthesized via an coaxial electrospinning. • The hollow Mo 2 C@C composites can enhance the performance during the alloying reactions. • The obtained nonofibers exhibit excellent rate capability and cycle stability. Abstract Hollow Mo 2 C@C core-shell nanofibers (H-Mo 2 C@C/NFs) have been successfully synthesized via an integrated procedure including coaxial electrospinning, oil extraction and carbonization. As an anode of lithium-ion batteries, H-Mo 2 C@C/NFs delivers high discharge capacity of 1176.3 mA h g−1 in the first cycle at a current density of 0.1 A g−1 and exhibits good rate capability and reversibility. The capacity can maintain at 595.1 mA h g−1 even when the current density is up to 5 A g−1. In addition, at a high current density of 1 A g−1, H-Mo 2 C@C/NFs also displays extraordinary long-term cycling performance with a capacity of 674.4 mA h g−1. The excellent rate performance and cycling stability result from the synergistic effect of Mo 2 C nanoparticles and hollow structure nanofiber matrix. Coaxial electrospinning technology can be widely extended to manufacture other metal carbide/carbon composites to achieve important energy storage and other applications. [ABSTRACT FROM AUTHOR]