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2D materials are regarded as promising electrocatalysts for water splitting because of their advances in providing ample active sites and improving electrochemical reaction kinetics. 2D MoSe2 has a greater intrinsic electrical conductivity and lower Gibbs free energy for reactant adsorption. However, there is still room for improvement in the electrocatalytic performance of MoSe2 for high‐performance electrochemical water splitting devices. Herein, the in situ preparation of heterostructure made of covalently bonded MoSe2 and rGO is reported. The obtained electrocatalyst contains the aggregated 3D structured MoSe2 over rGO, which is covalently bonded together with more edge sites. The active edge sites of MoSe2/rGO are dynamically involved in the electrocatalytic activity while facilitating electron transfer. Hence, the MoSe2/rGO heterostructure requires a low cell voltage of 1.64 V to reach 100 mA cm−2 in water splitting with high reaction kinetics. The aggregated MoSe2 over rGO with more edge sites exposed by the 3D structure of MoSe2 and the interfacial covalent bond in between them provides a favorable electronic structure for the HER and OER with low overpotentials and high current densities and enhances the stability of the electrocatalyst. This work presents an attractive and cost‐effective electrocatalyst suitable for industrial‐scale hydrogen fuel production. [ABSTRACT FROM AUTHOR]

All-solid-state batteries (ASSLBs) have gained attention as a next-generation battery technology. Halide solid electrolytes may be a candidate material for next-generation batteries due to their high stability in combination with cathode-active materials and good deformability. However, the halide solid electrolyte exhibits low ionic conductivity compared to other solid electrolytes, such as oxide and sulfide solid electrolytes. In this study, in order to improve the ionic conductivity, a strategy is presented to increase the ionic conductivity by changing the Li + concentration and metal charge by doping Mn2+ in the trigonal Li 2 ZrCl 6. Mn-doped Li 2 ZrCl 6 is synthesized by high-energy ball-milling. Structural analysis is conducted by powder X-ray diffraction, 7Li-Nuclear magnetic resonance, Raman spectroscopy and X-ray photoelectron spectroscopy. Electrochemical performance is evaluated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge measurement. Each value of ionic conductivity in the bare and optimized compositions is 0.4 mS cm−1 and 0.8 mS cm−1, respectively. The activation energy of Li 2 ZrCl 6 and 5 mol% Mn doped Li 2 ZrCl 6 is 0.342 and 0.326 eV. Galvanostatic charge-discharge is conducted to confirm cycling performance. The initial discharge capacity for Li 2 ZrCl 6 and 5 mol% Mn-doped Li 2 ZrCl 6 are 171.6 and 185.6 mAh g−1, respectively. [Display omitted] • Mn is successfully doped to Zr site in Li 2 ZrCl 6. • Ionic conductivity of 5 mol% Mn-doped Li 2 ZrCl 6 is 0.8 mS cm−1. • It showed a lower activation energy of 0.326 eV than Li 2 ZrCl 6 (0.342 eV). • Initial discharge capacity is improved from 171 mAh·g−1 to 186 mAh·g−1. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) are undoubtedly the most promising alternatives to lithium-ion batteries considering the natural abundance, distribution and cost of sodium resources. Still, SIBs face challenges in the development of suitable anode materials due to the large volume change during sodiation/de-sodiation, which results in inferior cycling stability. Herein, we synthesized a yolk–shell structured pyrrhotite (Fe1−xS)@N-doped carbon (FS@NC) through a solution-based method and investigated its electrochemical properties for use in SIBs as an anode material. The optimized yolk–shell structured FS@NC with distinctive voids and a core exhibited a high reversible capacity of 594 mA h g−1 over 100 cycles at 100 mA g−1, excellent rate capability and superior cycling performance compared to core–shell and pristine Fe1−xS materials. During the charge and discharge cycles, the synergistic effect of the porous core (Fe1−xS) with empty voids and a defective carbon shell configuration provided a large electrode/electrolyte contact area and shortened the diffusion path for electrons and sodium ions. It also mitigated the structural degradation by accommodating the volume change during continuous cycles, which was confirmed by ex situ SEM and TEM analyses. To demonstrate a practical application, we assembled a sodium-ion full cell with an O3-type NaCo0.5Fe0.5O2 cathode and a yolk–shell structured FS@NC anode, and the results showed superior energy storage performance. [ABSTRACT FROM AUTHOR]

• Nb 2 O 5 nanoparticles synthesized through facile sonochemical process. • Nb 2 O 5 @NC achieved via mixing of polyacrylonitrile followed by calcination. • Nb 2 O 5 @NC showed the high capacity of 96 mAh g−1 than bare Nb 2 O 5 (28 mAh g−1). Core-shell structured Nb 2 O 5 @NC nanoparticles are successfully prepared by facile sonochemical approach using polyacrylonitrile as a carbon and nitrogen source. The prepared particles are in orthorhombic phase of T-Nb 2 O 5 crystal structure and the particles exist in uniform spherical shape and size in the range of 60–80 nm. The Raman and XPS analysis confirms the presence of carbon and nitrogen in the prepared sample. The electrochemical performance demonstrates the good cycling stability of Nb 2 O 5 @NC electrode than pristine. Here, carbon aid to reduce the side reaction on the electrode/electrolyte interface and increase the electronic conductivity of the electrode thus leads to superior electrochemical performance. [ABSTRACT FROM AUTHOR]

The development of high ionic conducting solid electrolyte is one of the most active research topics in the field of lithium solid-state batteries. In the present study, we enhance the ionic conductivity of the lithium argyrodites using excess halogen substitution at the sulfur site. The halogen-rich Li 6-x PS 5-x Cl 1.0 Br x (0 ≤ x ≤ 0.5) composition is synthesized through a high-energy ball milling process followed by heat treatment. The ionic conductivity measurement reveals that Li 5.6 PS 4.6 Cl 1.0 Br 0.4 solid electrolyte exhibits a higher ionic conductivity value of 9.16 mS cm−1 than Li 6 PS 5 Cl (4.96 mS cm−1) at room temperature. The optimized electrolyte is utilized in a solid battery system thus shows a higher capacity of 188 mAh g−1 at 0.1C rate than Li 6 PS 5 Cl (181 mAh g−1). Interestingly, Li 5.6 PS 4.6 Cl 1.0 Br 0.4 solid electrolyte maintains the higher capacity retention (80.6%) than the Li 6 PS 5 Cl (75.3%) after 50 cycles. Further, we demonstrate the influence of excess halogen substitution through electrochemical kinetics using electrochemical impedance spectroscopy and galvanostatic intermittent titration technique. Finally, the air stability test indicates that Li 5.6 PS 4.6 Cl 1.0 Br 0.4 electrolyte delivers a high ionic conductivity of 5.26 mS cm−1 after 30 min dry air exposure. [Display omitted] • High ionic conducting halogen-rich argyrodite prepared via dry ball milling method. • Li 5.6 PS 4.6 Cl 1.0 Br 0.4 electrolyte delivered a ionic conductivity of 9.16 mS cm−1. • Solid state battery exhibited a high discharge capacity of 188 mAh g−1 at 0.1C. • Solid electrolyte showed a better conductivity of 5.26 mS cm−1 after dry air test. [ABSTRACT FROM AUTHOR]

• Antiperovskite-like Li 3 SI solid electrolyte was prepared by ball milling method. • Li 3 SI solid electrolyte exhibited the ionic conductivity value of 2.2 × 10−5 S/cm. • Electrochemical performance of Li 3 SI electrolyte was studied. Lithium-rich antiperovskite-type (LiRAP) solid electrolytes have received a great deal of attention due to their high mobile ion occupancy rate and narrow activation barrier. Oxide-based LiRAPs are widely studied. However, almost no reports are available on the electrochemical nature of sulfide-based LiRAPs. Here, we prepared the first antiperovskite-like Li 3 SI – solid solution type solid electrolyte and studied its electrochemical properties. The crystalline nature of the electrolyte was evaluated by powder X-ray diffraction. Electrochemical impedance spectroscopy showed that the Li 3 SI solid electrolyte exhibited an ionic conductivity of 2.2 × 10−5 S cm−1 at room temperature. The electrochemical stability of the electrolyte was studied with cyclic voltammetry and DC cycle tests, which showed that the proposed electrolyte was stable up to 10 V and >100 h, respectively. An assembled all-solid-state lithium battery using the Li 3 SI solid electrolyte exhibited an initial discharge capacity of 96.8 mAh g−1 at a current density of 3 mA g−1. [ABSTRACT FROM AUTHOR]