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A novel composite containing CoSe and porous carbon polyhedra (PCP), denoted as CoSe@PCP, was successfully synthesized using Co-based zeolitic imidazolate framework (ZIF-67) as precursor through a two-step method, including carbonization of ZIF-67 and subsequent selenization. The field-emission scanning electron microscopy and transmission electron microscopy characterizations confirm that CoSe nanoparticles are uniformly dispersed in PCP. When the CoSe@PCP was used as anode material for lithium-ion batteries, it exhibits superior performance with a high reversible capacity of 675 mAh g −1 at 200 mA g −1 after 100 cycles and 708.2 mAh g −1 at 1 A g −1 after 500 cycles as well as excellent cycling stability. Additionally, the CoSe@PCP also demonstrates excellent performance as anode material for sodium-ion batteries. A reversible capacity of 341 mAh g −1 can be obtained over 100 cycles at 100 mA g −1 with high cycling stability. The excellent battery performance of CoSe@PCP should be attributed to the synergistic effect of nanostructured CoSe and PCP derived from ZIF-67, in which the nanostructured CoSe possesses high reactivity towards lithium and sodium ions and the PCP can provide a continuous conductive matrix to facilitate the charge transfer and an effective buffering to mitigate the structure variation of CoSe during cycling. [ABSTRACT FROM AUTHOR]

In this work, sulfur-doped carbon spheres with hierarchical micro/mesopores (denoted as S-MCSs) were fabricated via a sol-gel method combined with surfactant-directing assembly strategy and subsequent sulfuration process. When used as anode materials of sodium-ion batteries (SIBs), S-MCSs show excellent electrochemical performance with a high maximum reversible capacity of 443.4 mA h g −1 after 50 cycles at 50 mA g −1 , and even at a high current density of 1 A g −1 , a reversible capacity of 238.2 mA h g −1 is obtained after 600 cycles, mainly due to their hierarchical micro/mesoporous structure with high specific surface area, large pore volume and high sulfur content. The excellent cycling performance and high capacity enable the S-MCSs to be a promising candidate for SIBs. [ABSTRACT FROM AUTHOR]

Porous carbon spheres (PCSs) with high surface area were fabricated by the reaction of D-Glucose monohydrate precursor with sodium molybdate dihydrate (Na 2 MoO 4 ·2H 2 O) via a facile hydrothermal method followed by carbonization and aqueous ammonia solution (NH 3 ·H 2 O) treatment. The as-prepared PCSs exhibit a highly developed porous structure with a large specific surface area and show an excellent electrochemical performance as anode material of sodium-ion batteries (SIBs). A reversible capacity of 249.9 mA h g −1 after 50 cycles at a current density of 50 mA g −1 and a long cycling life at a high current density of 500 mA g −1 are achieved. The excellent cycling performance and high capacity make the PCSs a promising candidate for long cycling SIBs. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide/carbon nanotubes (CNTs) sponge (GCNTS) is fabricated via a simple freeze drying of graphene oxide/CNTs mixed solution and subsequent thermal treatment in nitrogen atmosphere, and used as anodes for sodium-ion batteries (SIBs) for the first time. The morphology, structure and electrochemical performance of GCNTS are characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, nitrogen adsorption-desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The results show that GCNTS with 20 wt % CNTs has a highest charge capacity of 436 mA h g −1 after 100 cycles at a current density of 50 mA g −1 and even at a high current density of 10 A g −1 , a capacity of 195 mA h g −1 is maintained after 7440 cycles. The high capacity, excellent rate performance and long life cycling enable the GCNTS to be a promising candidate for practical SIBs. [ABSTRACT FROM AUTHOR]

Porous MnO@C nanorods were synthesized simply by annealing Mn-based metal-organic frameworks precursor. The morphology, structure and electrochemical performance of MnO@C hybrid were characterized by scanning electron microscopy, nitrogen adsorption/desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impendence spectroscopy. When used as anode material for sodium-ion batteries, the MnO@C hybrid exhibits a high reversible specific capacity of 260 mAh g −1 after 100 cycles at a current density of 50 mA g −1 . When the current density is increased to 2 A g −1 , the MnO@C delivers a superior long-life cycling performance with a capacity of 140 mAh g −1 at very high current density of 2 A g −1 . The excellent electrochemical performance of MnO@C can be attributed to its unique porous structure with MnO nanoparticles embedded in carbon matrix, which can apparently increase the electrical conductivity and buffer the volume change during the charge/discharge process. [ABSTRACT FROM AUTHOR]

N-doped porous carbon materials (NPCs) were prepared by the carbonization of covalent-organic frameworks as precursors and used as anodes for lithium and sodium ion batteries (LIBs and SIBs) for the first time. The morphology, structure and electrochemical performance were characterized and evaluated by field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, nitrogen adsorption and desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The NPCs not only show high maximum reversible charge capacities of 488 mAh g −1 at 100 mA g −1 (LIBs) and 237.7 mAh g −1 at 50 mA g −1 (SIBs) after 100 cycles, but also deliver high reversible charge capacities of 143 mAh g −1 at 5 A g −1 (LIBs) and 88.8 mAh g −1 at 2.5 A g −1 (SIBs) and excellent rate performance. Moreover, superior long-life cycling stability is observed for 5000 cycles even at a very high current density of 5 A g −1 for LIBs and 2.5 A g −1 for SIBs. The excellent electrochemical performance of NPCs with superior reversible capacity, good rate performance, and long-life cycling stability is attributed to their N doping, high specific surface area and porous structure with large interlayer distance. [ABSTRACT FROM AUTHOR]

MoO 3 /reduced graphene oxide (MoO 3 /RGO) composites were successfully prepared via a facile one-step hydrothermal method, and evaluated as anode materials for sodium ion batteries (SIBs). The crystal structures, morphologies and electrochemical properties of the as-prepared samples were characterized by X-ray diffraction, field-emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge tests, respectively. The results show that the introduction of RGO can enhance the electrochemical performances of MoO 3 /RGO composites. MoO 3 /RGO composite with 6 wt% RGO delivers the highest reversible capacity of ~208 mA h g −1 at 50 mA g −1 after 50 cycles with good cycling stability and excellent rate performance for SIBs. The excellent sodium storage performance of MoO 3 /RGO should be attributed to the synergistic effect between MoO 3 and RGO, which offers the increased electrical conductivity, the facilitated electron transfer ability and the buffering of volume expansion. [ABSTRACT FROM AUTHOR]

Porous cake-like TiO 2 was prepared simply by annealing Ti-based metal-organic frameworks templates. The morphology, structure and electrochemical performance of porous TiO 2 were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption, galvanostatic charge/discharge test, cyclic voltammetry and electrochemical impedance spectroscopy. When used as an anode for sodium ion batteries, porous TiO 2 exhibits a maximum charge capacity of 250 mAh g −1 after 50 cycles at a current density of 50 mA g −1 and delivers a remarkably stable reversible capacity of 173 mA g −1 after 2500 cycles even at a high current density of 1 A g −1 . The excellent electrochemical performance is attributed to the unique porous structure and suitable pore size of porous TiO 2 . [ABSTRACT FROM AUTHOR]

Sb 2 O 3 /reduced graphene oxide (RGO) composites were prepared through a facile microwave-assisted reduction of graphite oxide in SbCl 3 precursor solution, and investigated as anode material for sodium-ion batteries (SIBs). The experimental results show that a maximum specific capacity of 503 mA h g −1 is achieved after 50 galvanostatic charge/discharge cycles at a current density of 100 mA g −1 by optimizing the RGO content in the composites and an excellent rate performance is also obtained due to the synergistic effect between Sb 2 O 3 and RGO. The high capacity, superior rate capability and excellent cycling performance of Sb 2 O 3 /RGO composites demonstrate their excellent sodium-ion storage ability and show their great potential as electrode materials for SIBs. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon microspheres (NCSs) derived from oatmeal are employed as anodes for sodium ion batteries (SIBs). Their morphology, structure and electrochemical performance are characterized by field emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption isotherms, galvanostatic charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy, respectively. The results show that NCSs treated at 500 °C exhibit a high maximum charge capacity of 336 mA h g −1 after 50 cycles at a current density of 50 mA g −1 and even at a high current density of 10 A g −1 within 70 s charging time, a capacity of 104 mA h g −1 is maintained after 12500 cycles without obvious decay. The high capacity, excellent rate performance, long life cycling and ultrafast rechargeable ability enable the NCSs to be a promising candidate for practical SIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • 3D carbon-free nanoflower-like V 3 S 4 architecture was prepared via a facile method. • When used as anode of SIBs, V 3 S 4 exhibits superior sodium ion storage performance. • The electrochemical reaction mechanism of V 3 S 4 for sodium storage was investigated. Over the past years, transition metal sulfides, with remarkable redox reversibility, favorable electrical conductivity and superb theoretical capacity, have received considerable attention on the development of electrode materials that are capable of efficient and reversible storage of sodium ions. In this work, three-dimensional (3D) nanoflower-like V 3 S 4 was applied into sodium-ion batteries (SIBs) as anode, which was successfully synthesized via a facile solvothermal process with post-calcination treatment. The electrochemical measurements demonstrate that the as-prepared V 3 S 4 delivers a high reversible capacity of 499 mAh g−1 after 100 cycles at 0.1 A g−1. Furthermore, even at a high current density of 5 A g−1, the V 3 S 4 also exhibits an outstanding specific capacity of 299 mAh g−1 and a capacity retention rate of 58% compared with the capacity at 0.1 A g−1, which are superior to those of most vanadium sulfides for SIBs reported previously. Remarkably, the ultrahigh sodium-ion storage performance of V 3 S 4 should be ascribed to the unique nanoflower-like structure assembled by ultrathin nanosheets, which not only provides a large specific surface area, but also offers an adequate cushion to suppress the volume expansion during the sodiation-desodiation processes. More importantly, operando Raman spectra, ex-situ X-ray diffraction and ex-situ X-ray photoelectron spectroscopy were employed to demonstrate the evolution of the structure and chemical valence of V 3 S 4 , revealing that the high capacity of V 3 S 4 results from the cooperation of Na+ intercalation and conversion reaction. The findings of this study provide a better understanding on the sodium storage mechanism of V 3 S 4. [ABSTRACT FROM AUTHOR]

• NTP/M nanohybrid was synthesized by the transformation of Ti 3 C 2 MXene. • NTP/M nanohybrid was first applied for hybrid capacitive deionization. • NTP/M nanohybrid exhibited superior desalination performance and rate. The exploration and design of high-performance sodium-ion insertion host materials is of great significance to the development of hybrid capacitive deionization (HCDI). NaTi 2 (PO 4) 3 , abbreviated as NTP, is famous for its high theoretical sodium-ion storage performance, but due to the poor electrical conductivity, its desalination capacity has been largely limited. Herein we report the design and synthesis of NTP/MXene (NTP/M) nanohybrid by the transformation of Ti 3 C 2 MXene under solvothermal conditions. Due to its improved electrical conductivity and enhanced sodium-insertion ability with the introduction of MXene, the NTP/M nanohybrid shows an extraordinary desalination performance including a maximum deionization rate of 29.6 mg g−1 min−1, an ultrahigh desalination capacity of 128.6 mg g−1 and a stable cycling desalination ability, suggesting the promising application for practical HCDI. [ABSTRACT FROM AUTHOR]