•Carbon-constraint Fe3N nanoparticles were realized by a facile 2-step process.•First-principle calculation was carried out to clarify the reactions of Fe3N.•The ion migration at interfaces was detected by an impedance measurement.Carbon-constraint Fe3N nanoparticles (Fe3N@C) with a unique core-shell structure are successfully realized through a facile 2-step process: fabricating Fe@C core-shell nanoparticles by DC arc-discharge method and subsequently converting them into Fe3N@C through chemical nitriding reactions. A series of technological conditions are carried out to manipulate the core components and the shell structure. Owing to the protection of carbon shell, the nanoparticles own clear morphology and fine dispersion without distinct sintering. The Fe3N@C nanoparticles are applied as the anode material for lithium-ion batteries and exhibit high electric capacity in long-term cyclic charge/discharge process. Their excellent performance comes from the electrochemical lithiation/delithiation reactivity of the Fe3N core, while stable nanostructure of the electrodes sustained in the long cycles benefits from the constraint of carbon shell mostly.

•A highly porous carbon film was coated on nickel foam employing MPCVD.•A 3D-crosslinked nanoscale network owned high degree of graphitization.•High stability of 95% of capacitance retention after 10,000 cycles.•Ideal electric double-layer capacitive and quick charge/discharge behavior.•Facile synthetic route for large-scale production.Highly porous carbon film (PCF) coated on nickel foam was prepared successfully by microwave plasma-assisted chemical vapor deposition (MPCVD) with C2H2 as carbon source and Ar as discharge gas. The PCF is uniform and dense with 3D-crosslinked nanoscale network structure possessing high degree of graphitization. When used as the electrode material in an electrochemical supercapacitor, the PCF samples verify their advantageous electrical conductivity, ion contact and electrochemical stability. The test results show that the sample prepared under 1000 W microwave power has good electrochemical performance. It displays the specific capacitance of 62.75 F/g at the current density of 2.0 A/g and retains 95% of its capacitance after 10,000 cycles at the current density of 2.0 A/g. Besides, its near-rectangular shape of the cyclic voltammograms (CV) curves exhibits typical character of an electric double-layer capacitor, which owns an enhanced ionic diffusion that can fit the requirements for energy storage applications.

•Thermodynamic analyses of oxides on Sn-M nanoparticles surface.•The relationship between chemical components and electrochemical responses.•Sn-Fe nanoparticles show excellent electrode performance.A direct current arc-discharge method was applied to prepare the Sn–M (M=Fe, Al, Ni) bi-alloy nanoparticles. Thermodynamic is introduced to analyze the energy circumstances for the formation of the nanoparticles during the physical condensation process. The electrochemical properties of as-prepared Sn–M alloy nanoparticles are systematically investigated as anodes of Li-ion batteries. Among them, Sn–Fe nanoparticles electrode exhibits high Coulomb efficiency (about 71.2%) in the initial charge/discharge (257.9 mA h g−1/366.6 mA h g−1) and optimal cycle stability (a specific reversible capacity of 240 mA h g−1 maintained after 20 cycles) compared with others. Large differences in the electrochemical behaviors indicate that the chemical composition and microstructure of the nanoparticles determine the lithium-ion storage properties and the long-term cyclic stability during the charge/discharge process.The growth mechanism and electrochemical performance of Sn-based alloy nanoparticles.

•A simple arc-discharge approach for the synthesis of Sn-carbon nanotube nanocapsules, Sn nanorods semi-filled into the multi-walled CNTs are presented.•Provides a conductive network and a solution to the volume expansion issue of a high-capacity electrode.•According to the following figure. Charging and discharging mechanism of lithium ions were reflected in experiment and theory analysis.Direct current (DC) arc-discharge method is used to fabricate Sn-carbon nanotube nanocapsules (Sn-CNT NCs). The Sn is partially-filled into multi-walled CNTs, as an ideal configuration for the active materials as lithium-ion battery anode; Sn nanoparticles provide large storage capacity and CNTs confine and accommodate the volume expansion of Sn as well as provide the conductive network and contribute their own capacity. Large initial specific capacity and stable cyclic performance are identified in the electrochemical tests. Such novel nanostructure provides a solution to the volume expansion issue of a high-capacity electrode.

•Sn-alloy nanoparticles were synthesized successfully by DC arc-discharge method.•FeSn, FeSn2, Mg2Sn, Cu3Sn and Cu10Sn3 stably exist in the studied alloy nanoparticles.•Sn-Fe nanoparticles show the best cyclic capacity due to the activity of FeSn2.The electrochemical properties of Sn-M (M = Cu, Mg and Fe) bi-alloy nanoparticles prepared by DC arc-discharge method have been studied when these nanoparticles serve as the anode materials in Li-ion batteries (LIBs). Among all the alloy electrodes, the Sn-Fe electrode has the best initial specific capacity that maintains at about 227.3 mAh g−1 within 20 cycles. The intermetallic compounds in the nanoparticles have been characterized and thermodynamics analysis is introduced to elucidate the energy balance of their formation mechanism. As the electrochemical behaviours of the various alloy nanoparticles are different, we conclude that the present intermetallic compounds eventually determine the lithium-ion storage ability as well as the cyclic stability during the lithiation/delithiation process.