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For the first time, we successfully synthesize a self-supported Na 0.7 CoO 2 nanosheet arrays via the facile “sodiation and post-calcination” method. Different from the traditional high temperature solid-state technique, this facile strategy can easily maintain the novel construction of the precursor. A mass loading as high as 8 mg cm −2 is achieved for the Na 0.7 CoO 2 electrode with an initial capacity of 145.2 mAh g −1 at 1 C. Most importantly, the corresponding areal capacity for the Na 0.7 CoO 2 electrode is calculated to be 1.16 mAh cm −2 . This superb areal capacity is higher than that of the previously reported cathode materials. This special “sodiation and post-calcination” protocol mentioned in this article guarantees the high mass loading of Na 0.7 CoO 2 on Ni foam, providing a straightforward direction for engineering high-areal-capacity cathode materials. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical performance of LiFePO4/C samples synthesized by different carbon sources varies considerably, the structural difference of residual carbon in LiFePO4/C accounts for the performance variation. Higher performance is associated with a larger ratio of graphitic carbon, which exhibits better electronic conductivity than amorphous carbon. To improve the electronic conductivity, we prepared LiFePO4/(C+G) composites by a one-step solid-state method, in which natural graphite is used as reducing agent and conducting additives. The samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), Raman microprobe spectroscope and other electrochemical methods. The results show that reversible capacity and rate performance of LiFePO4 are improved considerably by the two-phase carbon coating. Therefore, LiFePO4/(C+G) composites are a promising candidate for lithium ion batteries. [Copyright &y& Elsevier]

The development of simple and efficient approaches to achieve high-performance electrode materials for supercapacitors is urgently needed at present. In this work, a facile and efficient hydrothermal approach (50 °C) is reported to prepare flower-like amorphous cobalt hydrogen phosphate (ACHP) architectures with significantly enhanced electrochemical activity as robust supercapacitor electrodes. These ACHP nanoflowers with numerous thin nanosheets are readily grown on nickel foam by using eco-friendly sodium hexametaphosphate (NaHMP) as phosphorus source and their formation mechanism is also revealed. The ACHP displays a high specific capacitance (411.2 F g−1 at 1 A g−1) as well as excellent rate capability (remained capacitance retention of 82.0% at 10 A g−1) due to the unique nanosheet-like architecture and the influence of structural water. In addition, this ACHP also exhibits an ultra-long lifespan that can maintain more than 97.6% capacitance retention after 10000 charge/discharge cycles. Therefore, this easy and effective one-step low temperature hydrothermal method offers a sustainable development strategy for energy storage devices in practical application. • ACHP nanosheets are prepared by a one-step low temperature hydrothermal method. • NaHMP is used as a novel phosphorus source. • ACHP electrode displays 97.6% capacitance maintained after 10000 GCD cycles. [ABSTRACT FROM AUTHOR]

Lithium sulfide (Li 2 S) is a promising cathode material for Lithium-sulfur (Li–S) batteries, but poor conductivity and electrochemical reactivity seriously hinders its applications. Herein, Ti 3 C 2 nanosheet (TNS) supported core-shell nano-Li 2 S@Li 3 PS 4 composite (NLi 2 S@LPS) is comprehensively designed to tackle these challenges. It displays fast Li+/e− transport kinetics, low energy barrier and high catalytic activity for the electrochemical redox reactions, which are derived from the synergistic effect of nano-sized Li 2 S, Li 3 PS 4 coating and catalytic MXene (Ti 3 C 2) components. The NLi 2 S@LPS/TNS composite electrode exhibits high utilization ratio of the active materials with low polarization and robust rate capability for charge/discharge, resulting in improved cycling stability for Li–S batteries. The Li–S batteries with NLi 2 S@LPS/TNS electrode have a capacity retention rate of 77% after 300 cycles of charge and discharge at 0.5C rate, corresponding to an average decay rate of 0.08% per cycle. • A core-shell NLi 2 S@LPS is synthesized to reduce the Li+/e−transport distance and provide ionic conductivity to the Li 2 S electrode. • The catalytic MXene nanosheets further promotes the LiPSs conversion kinetics and suppresses the shuttle effect. • The synergistic effect of NLi 2 S@LPS/TNS resulted in high utilization of the active material with good rate capability. [ABSTRACT FROM AUTHOR]

Resemblin, g core-shell electrocatalysts consisting of a Au core and Pd shell (Au@Pd) are synthesized via a Cu underpotential deposition (UPD)-Pd-displacement method. The Pd shell is non-uniform consisting of tiny Pd clusters with a coverage of 0.5–0.6. The ethanol oxidation reaction (EOR) activity of this kind of structure is much higher than Pd/C in an alkaline solution. The forward peak current density of Au@Pd is 5.4 times higher than that of Pd/C. Furthermore, the onset potential for EOR of the former is ∼100 mV more negative. An interesting particle size dependent EOR activity is also observed. With increasing the Au particle size (2.9, 5.8 and 6.5 nm), the EOR activity increases. The strain and ligand effects from the Au core, together with the bifunctional reaction mechanism in the Au–Pd system may be reasons for the enhanced activity in Au@Pd catalysts. [ABSTRACT FROM AUTHOR]

High capacity and superlong cycle life of Li 3 VO 4 have been actualized via carbon hybridization and N doping. The Li 3 VO 4 /N doped C (Li 3 VO 4 /N–C) that fabricated via an in situ carbonization method based on an intermedial solution phase delivers initial discharge and charge capacities of 686 and 540 mAh g −1 at a specific current of 0.15 A g −1 , which maintain of 538 and 536 mAh g −1 after 800 cycles, showing excellent cycle stability. Meanwhile, the Li 3 VO 4 /N–C exhibits superior rate performance and long life performance. After 150 cycles at various specific currents from 0.1 to 2.0 A g −1 , the discharge and charge capacities can restore 100% when reverting the specific current to 0.1 A g −1 . After 1100 cycles at a specific current of 2.0 A g −1 , the discharge and charge capacities can maintain of 340 and 337 mAh g −1 , showing no capacity attenuation in cycling. [ABSTRACT FROM AUTHOR]

Li 3 VO 4 /N-doped graphene with unique architecture of Li 3 VO 4 nanoparticles embed in N-doped graphene is successfully prepared via a facile method, which shows superior electrochemical performance as anode for Li-ion batteries. At a specific current of 0.15 A g −1 , it delivers discharge and charge capacities of 550 and 429 mAh g −1 in the initial cycle, which maintain of 478 and 476 mAh g −1 after 100 cycles. After 150 cycles at various specific currents from 0.1 to 2.0 A g −1 , the discharge capacity can restore to 487 mAh g −1 when reverting the specific current to 0.1 A g −1 . Meanwhile, even after 900 cycles at a specific current of 2.0 A g −1 , the Li 3 VO 4 /N-doped graphene electrode can deliver discharge and charge capacities of 195 and 193 mAh g −1 . [ABSTRACT FROM AUTHOR]

Coordinated electrochemical effect between Li 3 VO 4 and NiO occurs in Li 3 VO 4 /NiO/Ni electrodes owing to the close potential regions of lithiation and delithiation for Li 3 VO 4 and NiO. Remarkably, Li 3 VO 4 /NiO/Ni with bottom nanowalls and upper micro-flowers architecture undergoes a novel coordinated electrochemical reconstruction owing to well coordinated morphology variation of Li 3 VO 4 and NiO in lithiation and delithiation process, which leads to the formation of a new symmetrical porous architecture in cycling, resulting in superior electrochemical performance. At a specific current of 70 mA g −1 , it exhibits discharge and charge capacity of 860 and 631 mAh g −1 in the initial cycle, maintaining of 612 and 604 mAh g −1 after 100 cycles. After 60 cycles at various specific currents from 54 to 2700 mA g −1 , the discharge and charge capacity can restore to 612 mAh g −1 when reverting the specific current to 54 mA g −1 . [ABSTRACT FROM AUTHOR]

CoV 2 O 6 /natural graphite electrode with sodium alginate binder is prepared, which shows excellent electrochemical performance as anode for Li-ion batteries. It exhibits initial discharge and charge capacity of 902 and 638 mAh g −1 at a specific current of 110 mA g −1 . After 100 cycles, the discharge and charge capacity maintain of 669 and 665 mAh g −1 , respectively. The charge/discharge mechanism of CoV 2 O 6 is also studied, suggesting a structure variation in discharging, which involves the initial formation of LiV 2 O 5 and Co 3 V 2 O 8 , the subsequent transition from Co 3 V 2 O 8 to Li x V 2 O 5 and CoO, and the later reduction of CoO into Co. The structure variation of Co 3 V 2 O 8 accompanies by an amorphization process, which maintains in the subsequent discharging and charging process. [ABSTRACT FROM AUTHOR]

NiO nanowalls are directly grown on porous Ni foam via a facile electrochemical corrosion method and subsequent annealing, which show excellent cycle stability and rate capability as anode for lithium ion batteries. It delivers initial discharge and charge capacity of 1029 and 761 mAh g −1 at 0.15C, maintaining of 721 and 704 mAh g −1 after 100 cycles. After 60 cycles at various rates from 0.06 to 10C, the discharge capacity of the NiO/Ni can gradually restore when lowering the charge/discharge, finally arriving at 745 mAh g −1 after 30 cycles at 0.06C. The excellent electrochemical performance of the NiO/Ni electrode is relevant to a novel electrochemical reconstruction in cycling, which can be described as the initial formation of a large number of nanosized particles and the subsequent reassembly of these nanoparticles into a unique porous architecture. [ABSTRACT FROM AUTHOR]

Abstract: Li3VO4 is fabricated by a facile hydrothermal method and subsequent annealing treatment. The electrochemical performance and the possible charge/discharge mechanism of the as-prepared Li3VO4 as anode for Li-ion battery are firstly studied. Galvanostatic battery testing shows that the Li3VO4 electrode exhibits excellent cycle stability and rate capability. At a current density of 0.25 C, it delivers initial discharge and charge capacity about 624 and 481 mAh g−1, respectively, which maintains of 398 and 396 mAh g−1 after 100 cycles. After 60 cycles at various rates from 0.2 to 4.0 C, the discharge capacity can restore 98% when lowering the charge/discharge rate to 0.2 C. A possible redox reaction mechanism is proposed to interpret the lithiation/delithiation process of Li3VO4 according to experimental observations. The electrochemical reaction kinetic of the Li3VO4 electrode is studied by cyclic voltammetry measurement at various scan rate, which indicates the anodic and cathodic peak currents show linear dependence on the square root of scan rate from 0.3 to 1.0 mV s−1, suggesting a lithium ion diffusion controlled mechanism in the charge/discharge process. [Copyright &y& Elsevier]