Energy storage and conversion remain signifi cantly challenging to the research community. Among the candidates, lithium-ion batteries show great attraction and have been used in a wide range of applications, from small electronic devices, such as mobile phones and notebook computers, to increasing numbers of electric vehicles and large-scale energy storage equipments. [1][2][3][4][5][6] However, the relatively high cost of lithium resources shows the potential problems in terms of the long-term and large-scale applications of lithium-ion batteries. Lithium resources are limited; lithium makes up about 0.0065% of the earth ′ s crust and is unevenly distributed in South America. Thus, development of alternative storage devices is not only desirable but also necessary. Given this background, intense interest in the use of sodium-ion batteries particularly for largescale energy storage has recently been rekindled. Sodium, an element of electrochemical equivalence and proper potential, could be used as a substitute for lithium to meet the demands of rechargeable batteries. Furthermore, the sodium resources are considered to be unlimited and sodium salts widely exist in the sea. Therefore, sodium-ion batteries demonstrate the potential to substitute for lithium-ion batteries in the particular application in large-scale energy storage for renewable solar and wind power as well as smart grid. [ 7 , 8 ] Tremendous attention has been paid to sodium-ion batteries in recent years. Many electrode materials, such as Na x CoO 2 , [ 9 ] NaCrO 2 , [ 10 ] Na 1.0 Li 0.2 Ni 0.25 Mn 0.75 O δ , [ 11 , [ 17 ] hard carbon [ 13 , 18 , 19 ] and TiO 2 [ 20 ] have been investigated for application in sodium-ion batteries. Very recently, we reinvestigated the sodium ion insertion/extraction into/from Na 3 V 2 (PO 4 ) 3 with a NASICON structure. [ 21 ] The NASICON structure features a highly covalent three-dimensional framework that generates large interstitial spaces through which sodium ions may diffuse. [22][23][24] Our previous study was the fi rst to demonstrate that carbon coating can signifi cantly improve its sodium storage performance. [ 21 ] Carbon-coated Na 3 V 2 (PO 4 ) 3 electrodes show two fl at plateaus at 3.4 V and 1.6 V vs. Na + / Na, respectively. The voltage plateau located at 3.4 V is relatively higher than that of other cathode materials for sodium-ion batteries in recent reports. [9][10][11][12][13][14][15] However, the coulombic efficiency of the Na 3 V 2 (PO 4 ) 3 electrode in a half-cell is not as high as 99.5%, and does not even increase after the fi rst cycle, [ 21 ] likely because of the NaClO 4 /PC electrolyte used. Moreover, the storage capacity could also be enhanced by decreasing the carbon content of the composite and using optimized electrolyte system. In this contribution, Na 3 V 2 (PO 4 ) 3 /C nanocomposites with different carbon contents were prepared by a one-step solid state reaction and evaluated in different electrolyte systems. It was found that the sodium storage performance in terms of capacity...

Co(3)O(4) with three different crystal plane structures - cubes bounded by {001}planes, truncated octahedra enclosed by {111} and {001} planes, and octahedra with exposed {111}planes - is synthesized using a very simple one-step hydrothermal method. The three kinds of Co(3)O(4) exhibit significantly different electrochemical performances and the effect of different exposed crystal planes on the electrochemical performance of Co(3)O(4) is comprehensively studied.

Key indicators: single-crystal X-ray study; T = 293 K; mean (P-O) = 0.001 A ˚ ; disorder in solvent or counterion; R factor = 0.032; wR factor = 0.075; data-to-parameter ratio = 36.0. Single crystals of the title compound, trisodium divanadium-(III) tris(orthophosphate), were grown from a self-flux in the system Na 4 P 2 O 7-NaVP 2 O 7. Na 3 V 2 (PO 4) 3 belongs to the family of NASICON-related structures and is built up from isolated [VO 6 ] octahedra (3. symmetry) and [PO 4 ] tetrahedra (.2 symmetry) interlinked via corners to establish the framework anion [V 2 (PO 4) 3 ] 3À. The two independent Na + cations are partially occupied [site-occupancy factors = 0.805 (18) and 0.731 (7)] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (3. symmetry) and eightfold for the second (.2 symmetry) Na + cation. Related literature For structures and properties of complex phosphates with general formula Na 3 M III 2 (PO 4) 3 (M III = Sc, Fe, Cr), see: Collin et al. (1986); Genkina et al. (1991); Lazoryak et al. (1980); Lucazeau et al. (1986); Masquelier et al. (1992); Susman et al. (1983). For preparation of NaVP 2 O 7 which was used as an educt for crystal growth of the title compound, see: Zatovsky et al. (1999). Experimental Crystal data Na 3 V 2 (PO 4) 3 M r = 455.76 Trigonal, R3c a = 8.7288 (2) A ˚ c = 21.8042 (7) A ˚ V = 1438.73 (7) A ˚ 3 Z = 6 Mo K radiation = 2.66 mm À1 T = 293 K 0.20 Â 0.15 Â 0.10 mm Data collection Oxford Diffraction Xcalibur-3 CCD diffractometer Absorption correction: multi-scan (Blessing, 1995) T min = 0.635, T max = 0.780 12580 measured reflections 1331 independent reflections 1153 reflections with I > 2(I) R int = 0.063

In this work, we demonstrated the EG-assisted solvothermal synthesis of 3-D microspherical BiOBr architectures assembled by nanosheets. The morphology and compositional characteristics of the 3-D architectures were investigated by various microscopy techniques. The possible formation mechanism for the architectures was discussed. The band gap of the obtained BiOBr materials was estimated to be 2.54 eV by UV-vis. The specific surface area and porosity of the BiOBr 3-D architectures also were investigated by using nitrogen adsorption and desorption isotherms. Because of the narrow bandgap and the novel 3-D micro-/nanostructure, the BiOBr architectures show a more excellent photocatalytic activity under visible light irradiation than the BiOBr bulk plates. Several possible reasons for the higher photocatalytic activity have been taken into consideration. In addition, the photocatalyst is stable during the reaction and can be used repeatedly.