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Silicon suboxide (SiOx) is a promising anode material for lithium-ion batteries due to its high theoretical capacity (∼2400 mA h g-1) and good cycle performance. However, the volume effect during cycling and the poor intrinsic electronic conductivity restrict its practical application. Since SiO thin films with carbon additive are able to cope with these limitations, we have synthesized SiO/C thin film anodes containing various carbon contents by magnetron co-sputtering. Among the as-deposited electrodes, SiO/C-80 with a thickness of 1.15 μm showed superior electrochemical performance with an initial coulombic efficiency of ∼72%, a maximum reversible specific capacity of 1223 mA h g-1 and a capacity retention of 82.0% ± 0.5% after 750 cycles at a current density of 1 A g-1. The co-sputtered carbon is uniformly dispersed inside the film, which enhances the electronic conductivity and enables higher reversible capacity during the initial cycles. Meanwhile, the co-sputtered carbon plays a role in buffering volume change and maintaining electrode structure during further cycling. These results demonstrated that the SiO/C thin film anode has the application prospect as an anode material for lithium-ion batteries.

In this work, N, S co-doped pomelo peel derived carbon is successfully prepared by a simple one-step method. The derived carbon exhibits high specific capacitance (317 F g−1) and excellent rate capability (69.7% of capacitance retention at 15 A g−1), owing to its large SBET, high heteroatom doping rate and suitable graphitization degree (these characteristics are derived from the synergistic activation and reduction of thiourea dopant). The one-step method is applied to the other two biomasses (bamboo fiber and sugarcane bagasse). The derived carbons of the other two biomasses still show outstanding electrochemical performance due to their similar microstructure and chemical composition to pomelo peel derived carbon, which suggests the universality of the one-step method. The series of carbon materials are applied to symmetric supercapacitors, all of which show high energy density (30.6–24.6 Wh kg−1), indicating the potential application of such carbon materials in energy storage.

Metal sulfides have been drawing more and more attention as electrode materials in batteries due to their high theoretical capacities. However, the volume expansion and loss of active materials are two major problems, hindering further improvement in their electrochemical performances. Herein, a strategy based on physical confinement/chemical adsorption is proposed to fabricate CoS and Co9S8 electrodes for advanced lithium batteries. Via a facile two-step method, porous C/CNT micro/nano-spheres embedding cobalt sulfide nanoparticles are successfully fabricated, in which sulfur is immobilized by C S bonds. Physically, the porous C/CNT micro/nano-spheres well accommodate the volume change and inhibit the loss of active materials. Chemically, the sulfur species are anchored by C S bonds to alleviate the migration and loss. Assembled as lithium battery anodes, the porous cobalt sulfide/carbon composites, particularly the CoS/C/CNT (CoS-0.4C) and Co9S8/C/CNT (Co9S8-0.8C), exhibit superior lithium storage properties to those without any complexing or any C S bonding. Furthermore, an in-situ electrochemical measurement is proposed to detect the existence of Li2S, which is helpful to understand the mechanism of conversion reaction-based metal sulfides.

The commercial applications of rechargeable magnesium batteries (RMBs) are hindered by the slow diffusion kinetic of Mg2+ ions in cathode materials. To overcome this problem, we design a new Na-Mg hybrid battery with the NaTi2(PO4)3@Carbon (NTP@C) nanoparticles as a cathode material, the Mg metal as an anode and the Mg(TFSI)2 + NaBH4 - triglyme/1,2-Dimethoxyethane (DME) as a hybrid electrolyte. For the first time, the Mg(TFSI)2 is applied as a Mg2+ ions source in the chlorine-free Na-Mg hybrid electrolyte with NaBH4 as both Na+ ions source and moisture scavenger. The NTP@C/Mg hybrid battery shows excellent electrochemical performance. The corresponding average capacity decay after 1000 cycles is only 0.004% and 0.008% per cycle at 2 C and 10 C, respectively. Even at 20 C, about 60 mAh g−1 can be obtained after 26000 cycles. The impressive capacity retention of 93.7% and 90.2% can be obtained at 5 and 10 C, respectively. The excellent electrochemical performance of the hybrid battery confirms the feasibility using Mg(TFSI)2 in the chlorine-free hybrid electrolyte for long term cycle. The developed NTP@C/Mg hybrid battery possesses the advantages of excellent electrochemical performances, good safety and low cost, making it promising for the commercial applications, especially for the large-scale energy storages.

Ni3S2 nanoarrays directly growing on Ni foam are fabricated via an electrochemical corrosion method and used as freestanding electrode for sodium ion batteries. Based on high electronic conductivity facilitated by the 3D Ni backbone and fast surface redox reactions rendered by the ultrathin thickness of the Ni3S2 nanoarrays, high pseudocapacitive contribution for the charge storage is induced in the Ni3S2-Ni electrode. Remarkably, the capacitive contribution is self-adaptively enhanced in cycling owing to the gradually reduced and stabilized charge transfer resistance, triggering exceptional electrochemical performance. The Ni3S2-Ni electrode delivers ultra-stable cycling with charge/discharge capacities of 344.2/350.6 mAh g−1 after 200 cycles at 150 mA g−1 as well as high capacity recovery of 427 mAh g−1 after 70 cycles from 150 to 3000 mA g−1. Meanwhile, practical application for the Ni3S2-Ni electrode is also preliminarily assessed. It exhibits promising fast discharge/slow charge (750/150 mA g−1) performance with initial discharge/charge capacities of 285.4/275.7 mAh g−1 and 244.8/242.2 mAh g−1 after 300 cycles. When matching with Na3V2(PO4)3 cathode, it delivers discharge capacity of 347.8 mAh g−1 after 180 cycles at 200 mA g−1.

Li3VO4/C/rGO (HC-LVO/C/G) ternary composite with honeycomb-like structure is successfully prepared through a simple spray drying method with polystyrene (PS) microspheres as soft template. In this characteristic structure, carbon-coated Li3VO4 nanoparticles are well wrapped by rGO sheets and uniformly distributed within the honeycomb-like micrometer-sized clusters. The double coating layers of amorphous carbon and rGO can avoid the direct exposure of Li3VO4 nanoparticles to the electrolyte and enhance the electronic conductivity. Meanwhile, the honeycomb-like structure can shorten the diffusion paths of Li+ ions and favors the relaxation of the strain/stress during cycling. The resultant HC-LVO/C/G composite exhibits significantly improved high-rate performance and long cycle-life (the high reversible capacity of 312 mAh g−1 can be maintained after 1000 cycles at 10 C) compared with the contrastive Li3VO4/C composite synthesized by a typical solid-state reaction method.

In this work, CuS microspheres are synthesized by a facile microwave synthesis without any template or additive. As-prepared CuS microspheres display steady reversibility by adopting triethylene glycol dimethyl ether (TEGDME) as the electrolyte solvent and adjusting cut-off voltage to 0.6 − 3.0 V. The discharge capacity stands at 162 mAh g −1 after 200 cycles with the capacity retention of 95.8%. Electrochemical kinetics of CuS electrodes is investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) tests. Beyond that, electrochemical reactions of CuS electrodes are explored using ex-situ X-ray diffraction (XRD). As far as we know, it is not only the best performance of CuS electrodes in Na-ion batteries (NIBs) but also the first time that the kinetics and reaction mechanism of CuS in NIBs are investigated.

Li3VO4 (LVO) is a promising insertion-type anode material for lithium ion batteries (LIBs) while its electrochemical performance in magnesium ion batteries (MIBs) is rarely reported. Here, mesoporous LVO/Carbon (LVO/C) hollow spheres are synthesized by a facile spray-drying method and their electrochemical performance as Mg2+ insertion-host material is investigated for the first time. Galvanostatic charge-discharge results of LVO/C show no obvious platform in the potential range of 0.5∼2.5 V vs. Mg2+/Mg. The LVO/C delivers a high discharge capacity of 318 mAh g−1 at first cycle and exhibits good cycle performance. The electrochemical intercalation process is proved by element mapping, ex-situ X-ray Powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. Our results show that LVO is a promising anode material for MIBs.

Nanostructure construction and surface modification are effective ways to improve the electrochemical performances of electrode materials, especially for the conversion reaction-based materials. In this study, one-dimensional carbon coating bamboo-like Cu 2-x S nanorods have been delicately designed in a template-free method. The structure and morphology are well characterized via different instruments such as X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tested in lithium batteries as the anode, the Cu 2-x S@C electrode shows superior electrochemical performances to pristine Cu 2-x S. At 1 and 2 C, the Cu 2-x S@C nanorod electrode releases 309 and 277 mAh g −1 after 300 cycles. At high rates of 15 and 22 C, the electrode still exhibits 269 and 264 mAh g −1 . The kinetics of electrodes are also investigated by means of cyclic voltammetry (CV) and galvanostatic intermittence titration (GITT) measurements, proving the enhanced electrochemical properties. Thus, the one-dimensional bamboo-like Cu 2-x S voided nanorods can be a promising candidate for high-performance batteries.

Micro/nanostructured Co 9 S 8 cubes and spheres (S-Co 9 S 8 ) were successfully prepared with Co 3 O 4 as templates via the vapor-based anion exchange reaction. The morphology and structure of both materials were characterized by SEM and XRD. Co 9 S 8 microcubes and microspheres were composed of nanoparticles, inheriting the micro/nanostructure of Co 3 O 4 precursors. Tested in lithium ion batteries, C-Co 9 S 8 and S-Co 9 S 8 anodes exhibited high specific capacities, excellent cycle stability (C-Co 9 S 8 : 369 mAh g −1 , S-Co 9 S 8 : 370 mAh g −1 over 300 cycles at 1C) and high rate performances (C-Co 9 S 8 : 450 mAh g −1 , S-Co 9 S 8 : ∼430 mAh g −1 at 5C).

In this work, CuS/graphene (CuS-G) composite is synthesized via one-pot microwave irradiation method under ambient conditions. As anode material for lithium ion batteries, the CuS-G composite delivers a significantly enhanced reversible capacity and charge/discharge cycle stability compared with pristine CuS. A capacity of 348 mAh g−1 can be maintained after 1000 cycles at the current density of 2.0 A g−1. Electrochemical impedance spectroscopy (EIS) along with cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT) measurements indicate that the incorporation of graphene sheets reduces the contact resistance and enhances lithium ion transfer rate during the electrochemical lithium insertion/extraction remarkably. Thus, as-prepared CuS spheres can be a promising anode material for high performance lithium ion batteries.

Hydrogen plasma processing offers improved thermodynamics, kinetics and optimal reductive environment over conventional, thermal processing. In the current work, we report the first demonstration of hydrogen plasma treatment as a simple and effective strategy to fundamentally improve the performance of TiO 2 nanowires for lithium storage. In comparison to pristine TiO 2 nanowires, the hydrogen plasma treated TiO 2 (H-TiO 2 ) samples show substantially enhanced electron conductivity due to Ti 3+ introduction, which are successfully confirmed by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and four-probe testing instrument. More importantly, the H-TiO 2 electrode exhibits a higher rate capability and better reversibility. At charge/discharge current of 200, 800, 1600 and 3350 mA/g (10C), the discharge capacity of the H-TiO 2 electrode is 200, 162, 144 and 130 mAhg −1 . After 200 cycles at current of 200 mA/g, its capacity retention was 99.8% with almost no capacity fading. The electrochemical impedance spectra analyses and theoretical energy calculations using density functional theory (DFT) finally suggest that the hydrogenation process not only improves electronic conductivity due to the formation of Ti 3+ in the hydrogenation process but also dramatically augments lithium-ion mass transport within the crystalline lattice due to the introduction of Ti 3+ .

In this work, morphology-controlled lithium cobalt oxides (LCO) were obtained by a simple two-step method that involves a Co3O4 synthetic process, in which cubic and spherical Co3O4 were prepared by a hydrothermal method and a subsequent lithiation process with Li2CO3. The structures and morphologies of two materials were investigated by XRD, SEM and TEM. In contrast with the LCO prepared by using commercial Co3O4 precursor, the cubic and spherical LCO materials have an excellent performance in cyclic stability and rate capacity which is attributed to the better fluidity and less agglomeration with specific morphology of LCO materials.

Aluminum cobalt oxide-coated LiNi0.5Mn1.5O4 (LNMO) cathode materials are synthesized via a wet-coating method. The surface coating of the LNMO with cobalt aluminum oxide (CoAl2O4) does not alter its spinel structure, but greatly affects its thermostability. The complete, thin cobalt aluminum oxide coating layer strongly adheres to the host material and possesses a great thermal stability and electrochemical resistance, and it is not damaged in acid or alkali environments. The CoAl2O4 coating layer in this work successfully inhibits the dissolution of transition metal ions and maintain the stability of the LNMO structure. This CoAl2O4 coating layer also hold back the HF scavenger of the spinel structure in the electrolyte, which leads to enhanced electrochemical properties, especially at high temperatures. Furthermore, the coated LNMO exhibits an obviously improved thermostability compared with bare LNMO.

A facile and efficient electrostatic-assembly method to fabricate ball-milling-silicon@carbon/reduced-graphene-oxide composite (bmSi@C/rGO) has been developed. In the fabrication process, chitosan (CTS), as a charged bridge, connected ball milling silicon (bmSi) and graphene oxide (GO), and then was transformed into carbon coating by heat treatment. The carbon coated ball milling silicon (bmSi@C) particles were distributed evenly between the sheets of reduced graphene oxide (rGO). Therefore, the carbon coating and the wrinkled graphene sheets formed a superior conductive matrix and a buffer zone. The composite used as anode material exhibited high reversible capacity of 935.77 mAh g−1 and 71.9% capacity retention after 100 cycles. The excellent electrochemical properties are attributed to the well-designed structure, in which both the carbon layer and the rGO play an important role for improving the whole electrical conductivity and preventing the silicon from pulverization.

Increasing the charge voltage of a battery can greatly augment its specific capacity, but the increase of the voltage often brings some negative effects. Among them, the decomposition of the electrolyte at high voltage is a very serious problem. In this work, theoretical calculations are used to combine the advantages of each solvent, so that the designed electrolyte can effectively strengthen the high-voltage property of high-capacity NCM811/SiOx-Gr system batteries. The additive sulfolane is adopted to be oxidized in advance and build a protective film around the LiNi0·8Co0·1Mn0·1O2 positive electrode, and fluoroethylene carbonate is employed to be priorly reduced and form a film on the face of silicon oxide-graphite negative electrode. Compared with the traditional electrolyte, the cycling retention rate of the full battery is increased from 58.44% to 77.51% after cycling for 200 times under the voltage of 4.5 V with the high-performance electrolyte. From the results of a series of tests, it can be found that the high-voltage electrolyte can effectually maintain the structural of the cathode and anode materials at high voltages and improve the electrochemical performance. In addition, the electrolyte also has high conductivity and wettability with separator, which brings it a good application prospect.

In this study, N, S co-doped bamboo fiber derived carbon has been prepared when K3Fe(CN)6 and thiourea are selected as graphitization catalysis and dopant, respectively. The derived carbon possesses a large SBET, suitable graphitization degree, excellent conductivity and wettability of electrolyte, and particularly, it exhibits a unique sheet-like microstructure derived from the layer stripping of gas produced by thiourea pyrolysis, and these microstructure features are very beneficial for energy storage. Typically, the derived carbon displays a high specific capacitance of 328 F/g and an acceptable rate capability of 61.3% at 15 A g−1 in three-electrode systems. Meanwhile, the derived carbon-based coin-type symmetric supercapacitors are assembled in an aqueous electrolyte and an ionic liquid electrolyte, respectively, and they all show a considerable synergetic energy-power output performance (21.2 Wh kg−1 at 454 W kg−1 in aqueous electrolyte, and 61.6 Wh kg−1 at 300 W kg−1 in ionic liquid electrolyte), indicating the potential application of the derived carbon in supercapacitors.

Nanofibers fabricated by the electrospinning process have been used to construct sandwich-type Polyimide/Poly (vinylidene fluoride)/Polyimide (PI/PVDF/PI) separators with the thermal shutdown function for lithium ion batteries. This architecture uses the good thermal stability of PI as the top and bottom structure layers. Under high temperature operations, the middle layer made of PVDF nanofibers can melt and form a pore-free film to shut down the battery operation. The electrolyte uptake and ionic conductivity of the PI/PVDF/PI separator are superior to those of commercial polyolefin separators at 476% and 3.46 mS cm −1 , respectively, resulting better battery performances in terms of impedance, discharge capacity and cycle life. Under high temperature treatments above 170 °C, the self-shutdown function of the PI/PVDF/PI has been observed within 10 minutes, which could serve as the safety mechanism to defend the thermal runaway issue of lithium ion batteries. The effects of heating temperature and different time on the morphologies of each layer and electrolyte uptake of the separator are characterized as well.

anatase TiO2 nanowires lithium ion battery film electrodes hierarchical 3D nano-network silver mirror reaction A B S T R A C T A series of anatase TiO2 nanowires (TiO2-NWs) and Ag-modified TiO2 nanowires (TiO2@Ag-NWs) film electrodes with hierarchical 3D nano-network structure are successfully synthesized via a facile hydrothermal process followed by the traditional silver mirror reaction. Successful modification of silver nanoparticles onto the TiO2-NWs surface is confirmed by X-ray diffraction, scanning electron microscope, transmission electron microscopy with energy-dispersive X-ray analysis, and inductively coupled plasma technique. The electrochemical performances of the TiO2-NWs and TiO2@Ag-NWs film electrodes are also investigated in this work. Compared with the pristine TiO2-NWs, the TiO2@Ag-NWs nanomaterial exhibits a higher rate capability and better reversibility. At charge/discharge rates of 50, 100, 200, 400, 800,1600 and 3350 mA/g, the discharge capacities of the TiO2@Ag-NWs electrodes are 237, 219, 198, 179, 159, 139 and 120 mAh/g, respectively. After 120 cycles at 200 mA/g, its capacity retention was as high as 99.1% with little capacity fading.

Cuprous sulfide (Cu 2 S) is attractive electrode material for lithium-ion battery because of its high capacity and energy density. Interestingly, the cycling stability of cuprous sulfide is poor in the carbonate-based electrolytes used in lithium ion battery industry but excellent in ether-based electrolyte. In this study, we have compared the electrochemical performance of commercially available cuprous sulfide in various kinds of carbonate-based electrolytes. Our results show that the specific capacity of Cu 2 S electrode fades quickly in cyclic carbonate-based electrolytes, but a much better electrochemical performance in linear carbonate-based electrolytes. In linear carbonate-based electrolyte (1 M LiPF 6 in EMC), it exhibits a specific discharge capacity of 242.8 mAh g −1 after 50 cycles with coulombic efficiency of 99.6%. Our study suggests that the poor cycling performance of Cu 2 S in cyclic carbonate-based electrolytes is mainly due to the higher reactivity of cyclic carbonates with polysulfides on the surface of the electrode than linear carbonates, which was confirmed for the first time by our experiment studies and theoretical calculation.

This paper firstly reports a facile hydrothermal method to prepare CuFeS 2 spike-like nanorods as a promising anode material for lithium ion batteries. When being evaluated as an anode material in traditional carbonate-based (EC/DEC/DMC) and ether-based (DOL/DME) electrolytes, it's found that the type of the electrolytes plays a key role in contribution to the electrochemical performance. The CuFeS 2 binary mental sulfide material has initial discharge capacities of 632.6 mAh/g in the carbonate-based electrolyte and 674.9 mAh/g in the other at the rate of 0.2 C. After 50 circles, the discharge capacity decays severely, down to 64.3 mAh/g while the one performed in the ether-based electrolyte still possesses a capacity of 425.3 mAh/g, whose capacity retention is far more higher. Besides, an outstanding rate capability (∼190 mAh/g) can be obtained at a high rate of 10 C in the ether-based electrolyte, which is indicative of becoming promising anode materials for high-rate lithium batteries.

The novel Na-substituted Li 1-x Na x Ni 0.5 Mn 1.5 O 4 has been synthesized to use as a cathode material for lithium ion battery via a solid-state method. Both crystal domain size and lattice parameter are influenced by the doping content of Na, without changing the basic spinel structure. The doping of Na ions not only increase the disordered distribution of nickel and manganese cations in spinel, but also increase two additional electron hopping paths, which contribute to a better charge transfer ability, relieve the ohmic polarization and electrochemical polarization of materials and improve lithium ion diffusion coefficient. After Na-doped, the discharge specific capacity rises up comparing to the sample without Na-doped. As a result, the excellent rate capability is achieved for the doping content of 5% Na in spinel, that the discharge capacity is increased by 3.4%, 9.4%, 9.1%, 8.7%, 6.5% and 3.4% in comparison with LNMO, presenting a discharge specific capacity of 121, 119.4, 118.5, 115.1, 108.4 and 101.3mAh·g −1 at the rates of 0.2, 0.5, 1, 2, 5 and 10 C respectively, with tiny Mn 3+ platform appearing. In addition, the sample presents a discharge capacity of 125mAh·g −1 at 1 C, with a retention of 116.2mAh g −1 after 100 cycles. Even cycling at 5 C rate and 55 °C, the cell with 5% Na-doped LNMO cathode can has 82% of capacity retention after 400 cycles, indicating that it is a promising cathode material for lithium ion batteries.