Amorphous silicon thin films as a high capacity anodes for Li-ion batteries in ionic liquid electrolytes

High lithiation capacity at low red-ox potentials in combination with good safety characteristics makes amorphous Si as a very promising anode material for rechargeable Li batteries.Thin film silicon electrodes were prepared by DC magnetron sputtering of silicon on stainless steel substrates. Their behavior as Li insertion/extraction electrodes was studied by voltammetry and chronopotentiometry at room temperature in the ionic liquid (IL) 1-methyl-1-propylpiperidinium bis(trifluoromethylsuphonil)imide containing 1 M Li bis(trifluoromethylsuphonil)imide. Li/Si cells containing this electrolyte showed good performance with a stable Si electrodes capacity of about 3000 mA h g⁻¹ and a relatively low irreversible capacity. Preliminary results on cycling Si–LiCoO₂ cells using this IL electrolyte are also presented.     

Mesoporous Fe2O3 nanoparticles as high performance anode materials for lithium-ion batteries

This work introduces an effective, inexpensive, and large-scale production approach to the synthesis of Fe₂O₃ nanoparticles with a favorable configuration that 5 nm iron oxide domains in diameter assembled into a mesoporous network. The phase structure, morphology, and pore nature were characterized systematically. When used as anode materials for lithium-ion batteries, the mesoporous Fe₂O₃ nanoparticles exhibit excellent cycling performance (1009 mA h g^− 1 at 100 mA g^− 1 up to 230 cycles) and rate capability (reversible charging capacity of 420 mA h g^− 1 at 1000 mA g^− 1 during 230 cycles). This research suggests that the mesoporous Fe₂O₃ nanoparticles could be suitable as a high rate performance anode material for lithium-ion batteries.     

Investigation of immiscible alloy system of Al–Sn thin films as anodes for lithium ion batteries

The Al–Sn, which is immiscible alloy, film was prepared by e-beam deposition to explore the possibility as anode material for lithium ion batteries for the first time. The film has a complex structure with tiny Sn particles dispersed homogeneously in the Al active matrix. The diffusion coefficients of Li⁺ in these Al–Sn alloy films were determined to be 2.1–3.2 × 10⁻⁸ cm²/s by linear sweep voltammetry. The film electrode with high Al content (Al–33wt%Sn) delivered a high initial discharge capacity of 972.8 mA h g⁻¹, while the film electrode with high Sn content (Al–64wt%Sn) with an initial discharge capacity of 552 mA h g⁻¹ showed good cycle performance indicated by retaining a capacity of about 381 mA h g⁻¹ after 60 cycles. Our preliminary results demonstrate that Al–Sn immiscible alloy is a potential candidate for anodic material of lithium ion batteries.     

Room temperature Na/S batteries with sulfur composite cathode materials

Sodium/sulfur (Na/S) batteries were assembled with a sodium metal anode, liquid electrolyte and a sulfur composite cathode. Their electrochemical characteristics have been investigated at room temperature. Their charge/discharge curves indicate that sodium can reversibly react with sulfur at room temperature. The specific capacity of the sulfur composite cathode material in the first cycle was initially about 655 mA h g⁻¹ and stayed at about 500 mA h g⁻¹ up to the 18th cycle with about 100% charge/discharge efficiency.     

Fast fabrication of Ta2O5 nanotube arrays and their conversion to Ta3N5 for efficient solar driven water splitting

This work shows that highly ordered and mechanically stable micrometer-long Ta₂O₅ nanotube arrays can be fabricated by galvanostatic anodization in a few seconds. Typically, ~ 7.7 μm long nanotubes can be grown at 1.2 A cm^− 2 in only 2 s. Such nanotubes can be converted to Ta₃N₅ nanotube arrays by nitridation. Photoelectrochemical (PEC) water splitting using AM 1.5G illumination yields for the Ta₃N₅ nanotube photoanode modified with cobalt phosphate (Co–Pi) remarkable photocurrents of 5.9 mA cm ⁻² at 1.23 V_RHE and 12.9 mA cm ⁻² at 1.59 V_RHE and after Ba-doping a value of 7.5 mA cm ⁻² at 1.23 V_RHE is obtained.     

Structure and electrochemical hydrogen storage behaviors of alloy Co2B

The alloys Co₂B were prepared by two ways of high temperature solid phase process and arc melting, the structure of the alloys was characterized by XRD and SEM. It showed that it was structure of tetragonal Co₂B.The electrochemical experimental results demonstrated that the Co₂B prepared by two means both showed excellent cycling stability. The initial discharge capacity of Co₂B prepared by the high temperature solid phase process was 480.3 mA h g⁻¹, there was no distinct declination after 70 charge–discharge cycles and the capacity kept about 195 mA h g⁻¹. Co₂B prepared by the high temperature solid phase process showed very good electrochemical reversibility in CV curves. The hydrogen storage mechanism was also discussed, it confirmed that the high initial capacity of Co₂B prepared by the high temperature solid phase process was due to the oxidation of Co and B₂O₃, and it was irreversible.     

Nano-wire networks of sulfur–polypyrrole composite cathode materials for rechargeable lithium batteries

Polypyrrole (PPy) nanowire was synthesized through a surfactant mediated approach. The sulfur–polypyrrole (S–PPy) composite materials were prepared by heating the mixture of element sulfur and polypyrrole nanowire. The materials were characterized by FTIR, SEM. PPy with special morphology serves as conductive additive, distribution agent and absorbing agents, which effectively enhanced the electrochemical performance of sulfur. The initial discharge capacity of the active materials was 1222 mA h g⁻¹ the remaining capacity is 570 mA h g⁻¹ after 20th cycles.     

A layered δ-MnO2 nanoflake cathode with high zinc-storage capacities for eco-friendly battery applications

This study reports the use of a layered-type birnessite δ-MnO₂ nano-flake cathode for eco-friendly zinc-ion battery (ZIB) applications. The present δ-MnO₂ was prepared via the simple low temperature thermal decomposition of KMnO₄. The X-ray diffraction (XRD) pattern of the samples was well indexed to the δ-MnO₂ phase. Field emission SEM and TEM images of the δ-MnO₂ revealed flake-like morphologies with an average diameter of 200 nm. The electrochemical properties, investigated by cyclic voltammetry and constant current charge-discharge measurements, revealed that the nano-flake cathode exhibited first discharge capacity of 122 mAh g^− 1 under a high current density of 83 mA g^− 1 versus zinc. The discharge capacity thereafter increased until it reached 252 mAh g^− 1 in the fourth cycle. On the hundredth cycle, the electrode registered a discharge capacity of 112 mAh g^− 1. Coulombic efficiencies of nearly 100% were maintained on prolonged cycling and thereby indicate the long cycle stability of the δ-MnO₂. Besides, the realization of specific capacities of 92 and 30 mAh/g at high current densities of 666 and 1333 mA g⁻¹, respectively, clearly demonstrates the decent rate capabilities of δ-MnO₂ nano-flake cathode. These results may facilitate the utilization of layered-type birnessite δ-MnO₂ in ZIB applications.     

Fabrication and electrochemical performance of nickel ferrite nanoparticles as anode material in lithium ion batteries

Nano-sized nickel ferrite (NiFe₂O₄) was prepared by hydrothermal method at low temperature. The crystalline phase, morphology and specific surface area (BET) of the resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and nitrogen physical adsorption, respectively. The particle sizes of the resulting NiFe₂O₄ samples were in the range of 5–15 nm. The electrochemical performance of NiFe₂O₄ nanoparticles as the anodic material in lithium ion batteries was tested. It was found that the first discharge capacity of the anode made from NiFe₂O₄ nanoparticles could reach a very high value of 1314 mAh g⁻¹, while the discharge capacity decreased to 790.8 mAh g⁻¹ and 709.0 mAh g⁻¹ at a current density of 0.2 mA cm⁻² after 2 and 3 cycles, respectively. The BET surface area is up to 111.4 m² g⁻¹. The reaction mechanism between lithium and nickel ferrite was also discussed based on the results of cycle voltammetry (CV) experiments.     

Significant improved electrochemical performance of Li(Ni1/3Co1/3Mn1/3)O2 cathode on volumetric energy density and cycling stability at high rate

Li(Ni_1/3Co_1/3Mn_1/3)O₂ microspheres with a tap density of 2.41 g cm⁻³ have been synthesized for applications in high power and high energy systems, using a simple rheological phase reaction route. Cyclic voltammograms (CV) showed no shift of anodic and cathodic peaks centred at 3.81, 3.69 V for the Ni²⁺/Ni⁴⁺ couple after first cycle. The results of power pulse area specific impedance (ASI) and differential scanning calorimetry (DSC) tests showed lower power impedance and increased thermal stability of the electrode at high rate. These merits mentioned above provided significant improved capacity and rate performance for Li(Ni_1/3Co_1/3Mn_1/3)O₂ microspheres, which 159, 147 mAh g⁻¹ discharge capacity was delivered after 100 cycles between 2.5–4.6 V vs. Li at a different discharge rate of 2.5 C (500 mA g⁻¹), 5 C and a constant 0.5 C charge rate, respectively.     

One-step synthesis of hollow structured Si/C composites based on expandable microspheres as anodes for lithium ion batteries

Si/C composites of carbon hollow structures loaded with Si nanoparticles (NPs) (Si/C-HSs) were prepared by one-step pyrolysis of a mixture of Si NPs and expandable microspheres (EMs). For the Si/C-HSs, hollow carbon shells with rough surfaces were formed by directly carbonizing the polymer shells of EMs, and the Si NPs fell into the void space or were loaded on the rough surfaces of the carbon shells. The EM-based carbon shells accommodated the volume expansion of the Si NPs and improved the electrical conductivity of the composites. As a result, the Si/C-HSs exhibited a high capacity (initial reversible capacity: 854.4 mAh g^− 1 at 300 mA g^− 1), stable cycling performance (capacity retention: 80% after 50 cycles), and excellent rate capability.     

Si-doped Fe2O3 nanotubular/nanoporous layers for enhanced photoelectrochemical water splitting

The present work reports the enhancement of the photoelectrochemical water splitting performance of in-situ silicon (Si)-doped nanotubular/nanoporous (NT/NP) layers. These layers were grown by self-organizing anodization on Fe-Si alloys of various Si content. The incorporation of Si is found to retard the layer growth rates, leads to a more pronounced nanotubular morphology, and most importantly, an improved photoelectrochemical behavior. By increasing Si content from 1, 2 to 5 at.% in the iron oxide NT/NP photoanodes, the photocurrent onset potential shifts favorably to lower values. At 1.3 V vs. RHE, hematite layer with 5 at.% Si shows a 5-fold increase of the photocurrent, i.e. 0.5 mA cm^− 2 in comparison to 0.1 mA cm^− 2 for the undoped samples. The study also reveals that a suitable layer thickness is essential to achieve a beneficial effect of the Si doping.     

Aliphatic thioether polymers as novel cathode active materials for rechargeable lithium battery

Two aliphatic thioether polymers, poly[methanetetryl-tetra(thiomethylene)] (PMTTM) and poly(2,4-dithiopentanylene) (PDTP) were designed, synthesized, characterized and tested as cathode active materials. The chemical structure of polymers was confirmed by FT-IR, FT-Raman, and XPS spectral analysis. Both polymers were found to have electrochemical activity as cathode materials for rechargeable lithium battery by the electrochemical tests. The specific capacity of PMTTM was 504 mA h g⁻¹ at the third cycle and faded to 200 mA h g⁻¹ after 10 cycles; PDTP showed low and stable specific capacity around 100 mA h g⁻¹ even after 50 cycles. The specific capacity of fully saturated aliphatic thioether polymers demonstrated that thioether bonds offered energy storage. It was proposed that thioether bond was oxidized to form thioether cations with the help of ether solvents.     

Bismuth nanosheets grown on carbon fiber cloth as advanced binder-free anode for sodium-ion batteries

The bismuth nanosheets grown on carbon fiber cloth were designed. For sodium-ion batteries, the Bi/CFC electrode exhibited a high reversible capacity of 350 and 240 mAh g^− 1 after 300 cycles at 50 and 200 mA g^− 1, as well as a good rate capability. Besides, the electrode displayed two flat potential profiles during the charge/discharge process. The results suggest that the Bi/CFC electrode has excellent potential as an anode for sodium-ion batteries.     

Spherical Sn–Ni–C alloy anode material with submicro/micro complex particle structure for lithium secondary batteries

Submicro/micro-scaled spherical Sn–Ni–C alloy powders synthesized from oxides of Sn and Ni via carbothermal reduction at 900 °C were examined for use as anode materials in Li-ion battery. The synthesized spherical Sn–Ni–C particles show a loose micro-sized structure and a multi-phase composition. The reaction product carbon oxide gases yielded in the carbothermal reduction process should be responsible to the loose structure characteristics of Sn–Ni–C particles. The prepared Sn–Ni–C alloy composite electrode exhibits a stable reversible capacity of 310 mA h g⁻¹ at constant current density of 100 mA g⁻¹, and can be retained at 290 mA h g⁻¹ after 25 cycles. The space existing in loose particle can accommodate the large volume changes during charge/discharge cycling. The ductile component Ni plays as a buffer to relieve the mechanical stress induced by the large volume changes upon cycling. The remained carbon can prevent the aggregation between small alloy particles. All these factors contribute greatly to the excellent cycling stability of Sn–Ni–C alloy electrode. This carbothermal reduction method is simple, cheap and mass-productive, thus suitable to large scale production of alloy anode powders used for lithium ion batteries.     

Improving the cycleability of Si anodes by covalently grafting with 4-carboxyphenyl groups

In this study, the lithium storage capacity of Si nanoparticles is significantly enhanced by grafting with 4-carboxyphenyl groups via diazonium salts. The modified Si anodes exhibit reversible capacities of 1173 and 527 mA h g^?1 at the 1st and 50th cycle, while those of the bare Si electrodes are only 56 and 62 mA h g^?1, respectively. The improved electrochemical performance is supposed to arise from the formation of a robust and flexible solid electrolyte interface on the surfaces of the modified Si nanoparticles.     

Electrochemical properties of Li(Li(1−x)/3CoxMn(2−2x)/3)O2 (0 ⩽ x ⩽ 1) solid solutions prepared by poly-vinyl alcohol (PVA) method

The whole range of solid solutions Li(Li_(1−x)/3Co_xMn_(2−2x)/3)O₂ (0 ⩽ x ⩽ 1) was firstly synthesized by an aqueous solution method using poly-vinyl alcohol as a synthetic agent to investigate their structure and electrochemical properties. X-ray diffraction results indicated that the synthesized solid solutions showed a single phase without any detectable impurity phase and have a hexagonal structure with some additional peaks caused by monoclinic distortion, especially in the solid solutions with a low Co amount. In the electrochemical examination, the solid solutions in the range between 0.2 ⩽ x ⩽ 0.9 showed higher discharge capacity and better cyclability than LiCoO₂ (x = 1) on cycling between 2.0 and 4.6 V with 100 mA g⁻¹ at 25 °C. For example, Li(Li_0.2Co_0.4Mn_0.4)O₂ (x = 0.4) exhibited a high discharge capacity of 180 mA h g⁻¹ at the 50th cycle. By synthesizing the solid solution between Li₂MnO₃ and LiCoO₂, the electrochemical properties of the end members were improved.     

Highly active PtRuFe/C catalyst for methanol electro-oxidation

High methanol electro-oxidation activity was obtained on novel PtRuFe/C (2:1:1 at.%) catalyst. Mass and specific activities were 5.67 A  g⁻¹ catal. and 177 mA m⁻² for the PtRuFe/C catalyst while those of the commercial PtRu/C catalyst were 2.28 A g⁻¹ catal. and 87.7 mA m⁻², respectively. CO stripping results showed that on-set voltage for CO electro-oxidation was lowered by incorporation of Fe. XRD and XPS results revealed that Fe₂O₃ was formed instead of Fe(0), which resulted in large electron deficiency in Pt and easy CO electro-oxidation. The electron deficiency of Pt was proved by XPS results of Pt4f peaks, which moved to higher binding energies in PtRuFe/C than PtRu/C.     

Fabrication of porous carbon/Si composite nanofibers as high-capacity battery electrodes

Carbon/Si composite nanofibers with porous structures are prepared by electrospinning and subsequent carbonization processes. It is found that these porous composite nanofibers can be used as anode materials for rechargeable lithium-ion batteries (LIBs) without adding any binding or conducting additive. The resultant anodes exhibit good electrochemical performance; for example, a large discharge capacity of 1100 mAh g^?1 at a high current density of 200 mA g^?1.     

Electrodeposited PbO2 thin film on Ti electrode for application in hybrid supercapacitor

PbO₂ thin films were prepared by pulse current technique on Ti substrate from Pb(NO₃)₂ plating solution. The hybrid supercapacitor was designed with PbO₂ thin film as positive electrode and activated carbon (AC) as negative electrode in the 5.3 M H₂SO₄ solution. Its electrochemical properties were determined by cyclic voltammetry (CV), charge–discharge test and electrochemical impedance spectroscopy (EIS). The results revealed that the PbO₂/AC hybrid supercapacitor exhibited large specific capacitance, high-power and stable cycle performance. In the potential range of 0.8–1.8 V, the hybrid supercapacitor can deliver a specific capacitance of 71.5 F g^?1 at a discharge current density of 200 mA g^?1(4 mA cm^?2) when the mass ratio of AC to PbO₂ was three, and after 4500 deep cycles, the specific capacitance remains at 64.4 F g^?1, or 32.2 Wh Kg^?1 in specific energy, and the capacity only fades 10% from its initial value.