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In this article, Co-doped Na3V2-xTix(PO4)2F3(NVTPF x = 0, 0.1, 0.5, 0.7) sodium ion battery anode material was prepared by one-step hydrothermal method and it was coated with graphene. The crystal structure and morphology of NVTPF cathode material were characterized by scanning electron microscope and X-ray diffractometer. The results show that the particle diameter of the sample becomes smaller and the shape gradually becomes regular with the increase of Ti doping amount. The graphene coating did not change the crystal structure of NVTPF, but it was helpful to improve its electrochemical performance. The substitution of Ti4+ for V3+ contributes to improve the electronic conductivity and diffusion coefficient of sodium ions, reduce the charge transfer impedance, and accelerate the reaction kinetics of NVTPF electrode, thus significantly improving the cycling stability of NVTPF electrode. Among the four groups of materials, Na3v1.5Ti0.5(PO4)2F3 has the best electrochemical performance. At 1C, the specific capacity of initial discharge is 53.4 mAh/g, and the capacity retention rate of 35 cycles is 72.3%. The graphene coated NVTPF has a discharge capacity of 125.9mAh/g for the first cycle and 44.8mAh/g for 35 cycles at 1C. [ABSTRACT FROM AUTHOR]

In this paper, Co-doped Na3V2−xCox(PO4)2F3(x = 0,0.1,0.5,0.7) sodium ion battery anode material was prepared by one-step hydrothermal method, and Na3V1.5Co0.5(PO4)2F3 anode material coated with graphene was also prepared. It is confirmed that moderate Co2+ doping can improve the electrochemical performance of NVPF. Among all samples, Na3V1.5Co0.5(PO4)2F3@Graphene shows the best rate and cycle performance. It exhibits the highest specific capacity of 91.5 and 48.8 mAh/g at 1C, respectively when x = 0.5, after coating graphene, the charge-discharge specific capacities of 1C cycle are 128.2 mAh/g and 63.5 mAh/g for the first time, and 62.2 mAh/g and 45.1 mAh/g for 45 weeks.The performance results show that the excellent electrochemical performance of Na3V1.5Co0.5(PO4)2F3@Graphene can be attributed to the increase in electronic conductivity and ion diffusion coefficient. [ABSTRACT FROM AUTHOR]

[(Bi1/2Na1/2)0.92Ba0.05La0.02](Mg1/3Nb2/3)xTi(1-0.5x)O3(BNT-BLMNT, x = 0.01, 0.03,0.05,0.07) lead-free anti-ferroelectric ceramics were synthesized by a conventional solid-state. The effects of B-doped Mg4Nb2O9 groups on phase structures, compositional distribution and electrical properties of BNT-BLMNT ceramics were systematically investigated to further understand the mechanism of phase transition.It was found that the grain size of ceramic materials tends to decrease and the distribution becomes more uniform, indicating that Mg4Nb2O9 is conducive to the synthesis of ceramic materials in this system and effectively improves the grain size and distribution of this material with the increase of B-doped Mg4Nb2O9 group content. According to SEM and XRD analysis, Mg4Nb2O9 was completely dissolved in the ceramic crystal, forming a solid solution, all of which were of a single perovskite crystal structure.With the increase of it's content, the remnant polarization (Pr) decreased significantly, from 38.9 µC/cm2(x = 0.01) to 10.4 µC/cm2(x = 0.05), and the difference between the maximum polarization(Pmax) and the remnant polarization(Pr) became larger and larger, indicating that the addition of Mg and Nb elements increased the transition trend of the anti-ferroelectric phase. [ABSTRACT FROM AUTHOR]

(Bi0.46Na0.46Ba0.05La0.02)ZrxTi(1-x)O3(BNBLZT,x= 0.01, 0.03, 0.05, 0.07) lead-free anti-ferroelectric ceramics were synthesized by conventional solid-state reaction method. Microstructures and electrical properties of BNBLZT were investigated. Calculation from the X-ray diffraction results reveals that BNBLZT ceramic possesses a single perovskite structure phase. All BNBLZT ceramics show high density and the grain sizes decrease slightly with the addition of Zr concentration. In addition, theP-Ehysteresis loops measured at room temperature show that the largest energy-storage densityWmaxis 1.89 J/cm3. The temperature dependence of dielectric permittivity ϵrand dielectric loss tanδ illustrate that the addition of Zr can improve the piezoelectric properties of BNBLZT ceramics. [ABSTRACT FROM PUBLISHER]

0.96Pb(Ni1/3Nb2/3)O3-0.04PbZrO3(PNN-PZ) ceramics prepared via columbite method exhibit high crystallinity and high density, typical relaxor behavior is demonstrated by the dielectric data. The high dielectric tunability (˜87%) and low dielectric loss (˜0.007) were obtained for PNN-PZ at room temperature around 30kV/cm and 1 kHz, at fields below 13kV/cm, a double-wells model work well between tunability and dc bias electric field, in contrast, at all fields, the thermodynamic model can do better in fitting the dielectric nonlinear tunability behavior of the PNN-PZ ceramics than the double-wells model. These properties indicate that PNN-PZ ceramics might be a promising candidate for tunable materials. [ABSTRACT FROM PUBLISHER]