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Abstract: Li[Ni0.5Co0.2Mn0.3]O2 was prepared using nickel–cobalt–manganese hydroxide as the precursors, then resultant Li[Ni0.5Co0.2Mn0.3]O2 was surface modified by FePO4 through co-precipitation routine. The samples of bare and FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 were characterized with various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the thickness of FePO4-coating layer is about 5nm, and FePO4-coating layer not affects the crystal structure of the pristine Li[Ni0.5Co0.2Mn0.3]O2. Thus FePO4-coating layer is only a thin layer with amorphous structure. Furthermore, the FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 exhibits much better cycle performance, higher capacity retention ratios of 91.2% at 1C after 50 cycles since the FePO4-coating effectively prevents the reaction between active material and electrolyte on the process of charge/discharge under a high charge cutoff voltage of 4.6V. Meanwhile, the rate capability of FePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 is enhanced, and it obtained at 0.2, 0.5, 1, 2, 5 and 10C rates are 213.1, 207.9, 203.8, 190.2, 171.2 and 151.6mAhg−1, respectively. [Copyright &y& Elsevier]

The morphology-controlled Li 2 FeSiO 4 /C cathode material is successfully synthesized by a sol-gel method, in which commercial, spherical and cubic Fe 2 O 3 are respectively used as iron sources. By controlling the Fe 2 O 3 precursors' morphologies, the morphology and grain size of the Li 2 FeSiO 4 /C materials can be purposefully controlled via morphology-inheritance strategy. The morphologies, sizes, elemental distributions and structures of the as-prepared Li 2 FeSiO 4 /C materials are confirmed by field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results show that the as-synthesized Li 2 FeSiO 4 /C samples exhibit well-defined morphologies due to the homogeneous and well-crystallized Fe 2 O 3 precursors. Comparing with Li 2 FeSiO 4 /C synthesized by commercial Fe 2 O 3 precursor, the Li 2 FeSiO 4 /C materials prepared by spherical or cubic Fe 2 O 3 precursors exhibit eminent electrochemical properties, e.g., high initial reversible capacities of 214.1 mAh g −1 for LFS/C-S and 206.5 mAh g −1 for LFS/C-C at 0.1 C and good cyclic stability (93.1% for LFS/C-S and 91.5% for LFS/C-C). In particular, the spherical LFS/C-S material with better fluidity and less agglomeration displays excellent rate capability of 105.4 mAh g −1 at 10 C. Therefore, the control of the morphology and size during preparation process of Li 2 FeSiO 4 /C cathode materials will open a new route for the development of high performances lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based cathode materials (LRMCs) can be regarded as one of the most potential cathode materials for the next-generation high-energy Li-ion batteries due to the extra oxygen redox, which can greatly increase the actual output energy density of LRMCs. Nevertheless, the structure degradation and inevitable loss of oxygen will be triggered by the irreversible oxygen redox, which will cause a significant decline in cyclic performance and limited initial Coulombic efficiency, thus restricting their industrial applicability. Herein, the LRMCs with the submicron-sized single-crystal morphology and sodium doping are prepared by molten salt treatment with NaCl. On one hand, the submicron-sized single-crystal cathode effectively reduces the diffusion path for Li+ due to the smaller particle dimensions. On the other hand, Na+ doping expands the Li slab spacing, promoting the transport of Li+. The results show that the as-prepared material can purposefully alleviate oxygen release, improve structure stability, and increase the Li+ diffusion rate for the pristine LRMCs. Moreover, the as-prepared material in this study exhibits a higher reversible capacity of 282.8 mAh g−1 at 0.1 C and displays good cyclic performance, retaining a capacity rate of 80.9% after 200 cycles at 1 C. Therefore, this study offers a potential exploration for designing LRMCs with high energy density and excellent cyclic performance, which are achieved through building submicron-sized single-crystal morphology and introducing cationic doping. [Display omitted] • The Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO) is modified by the molten salt treatment with NaCl. • The obtained LMNCO characterizes submicron sized single crystal morphology and Na+ doping. • The submicron sized single crystal morphology and Na+ doping prompt the Li+ diffusion of LMNCO. • The enhanced specific capacity and initial Coulombic efficiency are obtained by the modified materials. [ABSTRACT FROM AUTHOR]

Tin-based materials possess a high-capacity as a potential anode for Na-ion batteries (SIBs), but the inferior electric conductivity and sluggish reaction kinetics limit their further development. In this paper, we have successfully constructed multiphase structure SnO 2 /SnS/SnS 2 by combining the electrochemical induction and in-situ hydrothermal method to effectively alleviate these problems. The continuous addition of sulfur source (thioacetamide, TAA) results in the formation of a transition from pure product (SnO 2) to double structure (SnO 2 /SnS), and finally multiphase structure (SnO 2 /SnS/SnS 2). Compared to single or bimetal chalcogenides, the tri-metal chalcogenides have strengthened synergistic effects between diverse components. Additionally, the SnO 2 /SnS/SnS 2 composites exhibit small grain size and abundant mesoporous structure, which aid to shorten the distance of ions transfer and increase surface active sites for Na-ions storage. The SnO 2 /SnS/SnS 2 anode displays optimal diffusion coefficient (1.94 × 10−15 cm2 s−1) and cycling durability, with a recoverable specific discharge ability of 401 mA h g−1 over 100 cycles at 100 mA g−1 and a maintenance overpasses 77 %. These results indicate that the construction of multiphase structures is a prospective way to improve the reaction kinetics of Sn-based materials for SIBs. • Tin-based multiphase structures were prepared through combining the electrochemical synthesis and in-situ hydrothermal. • The composite has abundant mesoporous structures and nanoscale amorphous particles, which aid in electrolyte infiltration. • Benefiting from the synergistic effects among three substances, the composites exhibit excellent electrochemical properties. [ABSTRACT FROM AUTHOR]

The exploitation of efficient electrocatalysts is vital for zinc-air batteries (ZABs). Fe-based catalysts exhibit insufficient bifunctional activity and stability, impeding the further development of ZABs. Herein, an efficient bifunctional electrocatalyst (PFeNC@NiFe-LDH) is rationally constructed and designed through the pore-creating and in-situ-generated interface nanoengineering approach. In this process, in-situ Fe-modified framework material (Fe-ZIF-8) regulates intermetallic distance to prevent Fe atom agglomeration. Fe-ZIF-8 and activator are co-heated to enable a highly porous structure and single-atom catalyst (PFeNC). The porous defect sites in PFeNC can be served as nucleation centers to anchor NiFe-LDH nanosheet, reinforcing the stability of the complex and enhancing bifunctional catalytic activity. Benefiting from single-atoms dispersing, interface effect, hierarchical pore channel, and synergistic effect, the PFeNC@NiFe-LDH demonstrates eminent bifunctional oxygen electrocatalytic performance (ΔE = 0.66 V), high stability, and rapid kinetic process (73.1 mV dec-1) for oxygen reduction reaction(ORR)), far outperforming the commercial Pt/C + IrO 2 benchmark (ΔE = 0.87 V). Furthermore, the PFeNC@NiFe-LDH as a ZABs air-electrode delivers prominent stability last 16 days. These results take a perspective to devise bifunctional composite catalysts with NiFe-LDH grown on carbon-based materials. • The strong interface structure of the composite material (PFeNC@NiFe-LDH) is prepared through in-situ interface nanoengineering. • The controlled distance of iron atoms is beneficial to catalyze the improvement of active sites. [ABSTRACT FROM AUTHOR]

Transition metal sulfides (TMSs) are utilized in supercapacitors as electrode materials for their high theoretical capacity. The fabrication of TMSs/carbon composite for supercapacitors has gained much interest because of its favorable electron conductivity, and mechanical strength. Herein, the biomass absorption method is applied to fabricate NiS/Ni 3 S 4 carbon composite. Carbon-wrapped nickel (Ni@C) is obtained through the carbonization of Ni2+ absorbed biomass. The wrapping structure can prevent nanoparticles from stacking and structure collapse. In the following process, utilizing Na 2 SO 4 as activator and sulfur source, it etches the carbon surface to create multistage pore structure, and meanwhile, the carbon matrix reduced part of SO 4 2- to form S2-/S that can be captured by the available active sites, leading to produce S-S/C-S bond. Subsequently, A-NiS/Ni 3 S 4 @C and NiS/Ni 3 S 4 @C were effectively obtained after sulfuring A-Ni@C and Ni@C in the condition of hydrothermal, respectively. Benefitting from the bonding structure and coating characteristics, A-NiS/Ni 3 S 4 @C presented better ion diffusion behavior and exhibited a specific capacity of 560.6 F g−1 at 1 A g−1, F g−1 higher than that of NiS/Ni 3 S 4 @C. Furthermore, the A-NiS/Ni 3 S 4 @C was also assembled into a hybrid supercapacitor and showed a specific capacity of 118.6 F g−1 at 1 A g−1. • Biomass-derived carbon well confined NiS/Ni 3 S 4 nanoparticles was successfully prepared. • Nanoparticles can be obtained efficiently via biomass absorption method. • Na 2 SO 4 can enhance the property in a mild way by etching the carbon surface physically and form C-S/S-S. • Offering a new method for the fabrication of nanocomposite and mild way for polish the properties of carbon. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Y2O3 coated LiMn2O4 microsphere wrapped with graphene is firstly synthesized. [•] The graphene/Y2O3/LiMn2O4 hybrid shows the notable rate and cycling performance. [•] Y2O3 and graphene modification can effectively improve the performance of material. [ABSTRACT FROM AUTHOR]

Highlights: [•] BiPO4 is initially reported as a cathode material for lithium-ion batteries. [•] We have explored that BiPO4 is a cathode material based on conversion reactions. [•] Its theoretical specific capacity and output voltage are 264.5mAhg−1 and 3.14V. [•] Its theoretical volumetric energy density is close to twice higher than LiCoO2. [•] Effects of the phase transformation on electrochemistry of BiPO4 are discussed. [ABSTRACT FROM AUTHOR]