Hierarchical porous ZnMnO3 yolk–shell microspheres with superior lithium storage properties enabled by a unique one-step conversion mechanism

ZnMnO₃ has attracted enormous attention as a novel anode material for rechargeable lithium-ion batteries due to its high theoretical capacity. However, it suffers from capacity fading because of the large volumetric change during cycling. Here, porous ZnMnO₃ yolk–shell microspheres are developed through a facile and scalable synthesis approach. This ZnMnO₃ can effectively accommodate the large volume change upon cycling, leading to an excellent cycling stability. When applying this ZnMnO₃ as the anode in lithium-ion batteries, it shows a remarkable reversible capacity (400 mA h g⁻¹ at a current density of 400 mA g⁻¹ and 200 mA h g⁻¹ at 6400 mA g⁻¹) and excellent cycling performance (540 mA h g⁻¹ after 300 cycles at 400 mA g⁻¹) due to its unique structure. Furthermore, a novel conversion reaction mechanism of the ZnMnO₃ is revealed: ZnMnO₃ is first converted into intermediate phases of ZnO and MnO, after which MnO is further reduced to metallic Mn while ZnO remains stable, avoiding the serious pulverization of the electrode brought about by lithiation of ZnO.

ZnMnO₃ has attracted enormous attention as a novel anode material for rechargeable lithium-ion batteries due to its high theoretical capacity.     

Development of an efficient CVD technique to prepare TiO2/porous–carbon nanocomposites for high rate lithium-ion capacitors

Titanium dioxide is a promising electrode material for lithium-ion capacitors. When using TiO₂ as an electrode material, it is necessary to combine it with carbon at the nanometer level to improve its low electrical conductivity and low reactivity with Li⁺. However, preparation methods of reported TiO₂/porous–carbon nanocomposites are generally not cost-effective, and their productivities are low. In this study, the vacuum liquid-pulse chemical vapor deposition (VLP-CVD) technique was developed to easily prepare TiO₂/porous–carbon nanocomposites, where TiO₂ nanoparticles with a diameter of ∼4 nm could be homogeneously deposited inside the pores of meso- or macroporous carbons. Because the deposited TiO₂ nanoparticles had access to effective electrically conductive paths formed by the porous–carbon substrate, they showed a high discharge capacity of ∼200 mA h g⁻¹-TiO₂ (based on TiO₂ weight). In particular, the composite prepared from macroporous carbon showed an extremely high rate performance, where 50% of the discharge capacity was retained at a current density of 15 000 mA g⁻¹ when compared to that measured at 50 mA g⁻¹. In addition, the composite also showed very high cyclability, where 80% of the discharge capacity was retained at the 10 000^th cycle. Because the VLP-CVD technique can be performed using simple apparatus and commercially available starting materials, it can be expected to boost industrial production of TiO₂/porous–carbon for lithium-ion capacitors.

TiO₂ nanoparticles with a diameter of around 5 nm were homogeneously deposited inside the pores of meso-macroporous carbons.     

Improved cycling performance and rate stability of ITO-compounded Li2MnSiO4 for lithium-ion batteries

Li₂MnSiO₄ compounded with indium tin oxide (ITO) was successfully synthesized through a sol–gel method. The structure and morphology characterization of Li₂MnSiO₄/ITO nanocomposite are demonstrated by XRD, SEM, TEM, EDS and XPS. Galvanostatic charge–discharge tests, EIS and CV are employed to examine the electrochemical performance of the composite. From those results, it could be observed that the electrochemical performance of Li₂MnSiO₄ cathode material has been significantly improved due to the introducing of indium tin oxide. The 3 wt% ITO-compounded sample displayed a discharge specific capacity around 141 mA h g⁻¹ at 0.05C, 134.4 mA h g⁻¹ at 0.1C, 132.9 mA h g⁻¹ at 0.2C and 127.4 mA h g⁻¹ at 0.5C in the first cycle, which is much higher than the pristine sample.

Li₂MnSiO₄ compounded with indium tin oxide (ITO) was successfully synthesized through a sol–gel method.     

TiO2-decorated porous carbon nanofiber interlayer for Li–S batteries

Lithium–sulfur (Li–S) batteries are the most promising energy storage systems owing to their high energy density. However, shuttling of polysulfides detracts the electrochemical performance of Li–S batteries and thus prevents the commercialization of Li–S batteries. Here, TiO₂@porous carbon nanofibers (TiO₂@PCNFs) are fabricated via combining electrospinning and electrospraying techniques and the resultant TiO₂@PCNFs are evaluated for use as an interlayer in Li–S batteries. TiO₂ nanoparticles on PCNFs are observed from SEM and TEM images. A high initial discharge capacity of 1510 mA h g⁻¹ is achieved owing to the novel approach of electrospinning the carbon precursor and electrospraying TiO₂ nanoparticles simultaneously. In this approach TiO₂ nanoparticles capture polysulfides with strong interaction and the PCNFs with high conductivity recycle and re-use the adsorbed polysulfides, thus leading to high reversible capacity and stable cycling performance. A high reversible capacity of 967 mA h g⁻¹ is reached after 200 cycles at 0.2C. The cell with the TiO₂@PCNF interlayer also delivers a reversible capacity of around 1100 mA h g⁻¹ at 1C, while the cell without the interlayer exhibits a lower capacity of 400 mA h g⁻¹. Therefore, this work presents a novel approach for designing interlayer materials with exceptional electrochemical performance for high performance Li–S batteries.

Lithium–sulfur (Li–S) batteries are the most promising energy storage systems owing to their high energy density.     

Preparation of cobalt sulfide@reduced graphene oxide nanocomposites with outstanding electrochemical behavior for lithium-ion batteries

Cobalt sulfide@reduced graphene oxide composites were prepared through a simple solvothermal method. The cobalt sulfide@reduced graphene oxide composites are composed of cobalt sulfide nanoparticles uniformly attached on both sides of reduced graphene oxide. Some favorable electrochemical performances in specific capacity, cycling performance, and rate capability are achieved using the porous nanocomposites as an anode for lithium-ion batteries. In a half-cell, it exhibits a high specific capacity of 1253.9 mA h g⁻¹ at 500 mA g⁻¹ after 100 cycles. A full cell consists of the cobalt sulfide@reduced graphene oxide nanocomposite anode and a commercial LiCoO₂ cathode, and is able to hold a high capacity of 574.7 mA h g⁻¹ at 200 mA g⁻¹ after 200 cycles. The reduced graphene oxide plays a key role in enhancing the electrical conductivity of the electrode materials; and it effectively prevents the cobalt sulfide nanoparticles from dropping off the electrode and buffers the volume variation during the discharge–charge process. The cobalt sulfide@reduced graphene oxide nanocomposites present great potential to be a promising anode material for lithium-ion batteries.

Cobalt sulfide@reduced graphene oxide nanocomposites obtained through a dipping and hydrothermal process, exhibit ascendant lithium-ion storage properties.     

Ultrafast-charging and long cycle-life anode materials of TiO2-bronze/nitrogen-doped graphene nanocomposites for high-performance lithium-ion batteries

Emerging technologies demand a new generation of lithium-ion batteries that are high in power density, fast-charging, safe to use, and have long cycle lives. This work reports charging rates and specific capacities of TiO₂(B)/N-doped graphene (TNG) composites. The TNG composites were prepared by the hydrothermal method in various reaction times (3, 6, 9, 12, and 24 h), while the N-doped graphene was synthesized using the modified Hummer''s method followed by a heat-treatment process. The different morphologies of TiO₂ dispersed on the N-doped graphene sheet were confirmed as anatase-nanoparticles (3, 6 h), TiO₂(B)-nanotubes (9 h), and TiO₂(B)-nanorods (12, 24 h) by XRD, TEM, and EELS. In electrochemical studies, the best battery performance was obtained with the nanorods TiO₂(B)/N-doped graphene (TNG-24h) electrode, with a relatively high specific capacity of 500 mA h g⁻¹ at 1C (539.5 mA g⁻¹). In long-term cycling, excellent stability was observed. The capacity retention of 150 mA h g⁻¹ was observed after 7000 cycles, at an ultrahigh current of 50C (27.0 A g⁻¹). The synthesized composites have the potential for fast-charging and have high stability, showing potential as an anode material in advanced power batteries for next-generation applications.

The TiO₂-bronze/nitrogen-doped graphene nanocomposites have the potential for fast-charging and have high stability, showing potential as an anode material in advanced power batteries for next-generation applications.     

TiO2-coated LiCoO2 electrodes fabricated by a sputtering deposition method for lithium-ion batteries with enhanced electrochemical performance

We fabricated lithium cobalt oxide (LiCoO₂, LCO) electrodes in the absence and presence of TiO₂ layers as cathodes for lithium-ion batteries (LIBs) using a sputtering deposition method under an Ar atmosphere. In particular, TiO₂ coating layers on sputtered LCO electrodes were directly deposited in a layer-by-layer form with varying TiO₂ sputtering times from 60 to 120 s. These sputtered electrodes were heated at 600 °C in an air atmosphere for 3 h. The thicknesses of TiO₂ layers in TiO₂-coated LCO electrodes were controlled from ∼2 to ∼10 nm. These TiO₂-coated LCO electrodes exhibited superior electrochemical performance, i.e. high capacities (93–107 mA h g⁻¹@0.5C), improved retention of >60% after 100 cycles, and high-rate cycling properties (64 mA h g⁻¹@1C after 100 cycles). Such an improved performance of TiO₂-coated LCO electrodes was found to be attributed to relieved volumetric expansion of LCO and protection of LCO electrodes against HF generated during cycling.

We fabricated lithium cobalt oxide (LiCoO₂, LCO) electrodes in the absence and presence of TiO₂ layers as cathodes for lithium-ion batteries (LIBs) using a sputtering deposition method under an Ar atmosphere.     

K-doped Li2ZnTi3O8/C as an efficient anode material with high performance for Li-ion batteries

Li₂ZnTi₃O₈/C and Li_1.9K_0.1ZnTi₃O₈/C were successfully synthesized using the sol–gel method. Doping K apparently yielded a wider tunnel, helpful for increasing the rate of transport of lithium ions, and furthermore yielded excellent electrochemical properties. The first discharge capacity for Li_1.9K_0.1ZnTi₃O₈/C was 352.9 mA h g⁻¹ at a current density of 200 mA g⁻¹. Li_1.9K_0.1ZnTi₃O₈/C also performed stably, retaining a capacity of 323.7 mA h g⁻¹ at the 100th cycle, indicative of its excellent cycling properties. In the rate performance test, Li_1.9K_0.1ZnTi₃O₈/C showed at the first cycle a high discharge capacity of 379.5 mA h g⁻¹ for a current density of 50 mA g⁻¹ and a capacity of 258.9 mA h g⁻¹ at 1000 mA g⁻¹. The results indicated that K-doping should be considered a useful method for improving electrochemical performances.

(A and B) CV curves of (A) Li₂ZnTi₃O₈/C and (B) Li_1.9K_0.1ZnTi₃O₈/C, (C) Initial charge–discharge curves and (D) cycling capacity and (E) rate performances of Li₂ZnTi₃O₈/C and Li_1.9K_0.1ZnTi₃O₈/C. (F) The composition of the CR2032 cell.     

A stable TiO2–graphene nanocomposite anode with high rate capability for lithium-ion batteries

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries. With the assistance of hydrazine hydrate as a reducing agent, graphene oxide was reduced while TiO₂ nanoparticles were grown in situ on the nanosheets to obtain the nanocomposite material. The morphology of the nanocomposite obtained consisted of TiO₂ particles with a size of ∼100 nm, uniformly distributed on the reduced graphene oxide nanosheets. The as-prepared TiO₂–graphene nanocomposite was able to deliver a capacity of 250 mA h g⁻¹ ± 5% at 0.2C for more than 200 cycles with remarkably stable cycle life during the Li⁺ insertion/extraction process. In terms of high rate capability performance, the nanocomposite delivered discharge capacity of ca. 100 mA h g⁻¹ with >99% coulombic efficiency at C-rates of up to 20C. The enhanced electrochemical performance of the material in terms of high rate capability and cycling stability indicates that the as-developed TiO₂–rGO nanocomposites are promising electrode materials for future Li-ion batteries.

A rapid microwave hydrothermal process is adopted for the synthesis of titanium dioxide and reduced graphene oxide nanocomposites as high-performance anode materials for Li-ion batteries.     

Role of polyvinylpyrrolidone in the electrochemical performance of Li2MnO3 cathode for lithium-ion batteries

While Li₂MnO₃ as an over-lithiated layered oxide (OLO) shows a significantly high reversible capacity of 250 mA h g⁻¹ in lithium-ion batteries (LIBs), it has critical issues of poor cycling performance and deteriorated high rate performance. In this study, modified OLO cathode materials for improved LIB performance were obtained by heating the as-prepared OLO at different temperatures (400, 500, and 600 °C) in the presence of polyvinylpyrrolidone (PVP) under an N₂ atmosphere. Compared to the as-prepared OLO, the OLO sample heated at 500 °C with PVP exhibited a high initial discharge capacity of 206 mA h g⁻¹ and high rate capability of 111 mA h g⁻¹ at 100 mA g⁻¹. The superior performance of the OLO sample heated at 500 °C with PVP is attributed to an improved electronic conductivity and Li⁺ ionic motion, resulting from the formation of the graphitic carbon structure and increased Mn³⁺ ratio during the decomposition of PVP.

The modified OLO cathode materials for improved LIB performance were obtained by heating the as-prepared OLO in the presence of polyvinylpyrrolidone (PVP) under an N₂ atmosphere.     

Dendritic nanostructured FeS2-based high stability and capacity Li-ion cathodes

Here we show that dendritic architectures are attractive as the basis of hierarchically structured battery electrodes. Dendritically structured FeS₂, synthesized via simple thermal sulfidation of electrodeposited dendritic α-Fe, was formed into an electrode and cycled vs. lithium. The reversible capacities of the dendritic FeS₂ cathode were 560 mA h g⁻¹ at 0.5C and 533 mA h g⁻¹ at 1.0C after 50 cycles over 0.7–3.0 V. Over 0.7–2.4 V, where the electrode is more stable, the reversible capacities are 348 mA h g⁻¹ at 0.2C and 179 mA h g⁻¹ at 1.0C after 150 cycles. The good cycling performance and high specific capacities of the dendritic FeS₂ cathodes are attributed to the ability of a dendritic structure to provide good ion and electron conducting pathways, and a large surface area. Importantly, the dendritic structure appears capable of accommodating volume changes imposed by the lithiation and delithiation process. The presence of a Li_2−xFeS₂ phase is indicated for the first time by high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) electron energy loss spectroscopy (EELS). We suspect this phase is what enables electrochemical cycling to possess high reversibility over 0.7–2.4 V.

High performance dendritically structured FeS₂ cathodes are systemically studied. The dendritic structure is resistant to volume changes during cycling, increasing cyclability. The presence of Li_2–xFeS₂, which also enhances cyclability, is confirmed.     

In situ production of a two-dimensional molybdenum disulfide/graphene hybrid nanosheet anode for lithium-ion batteries

A solvent-free, low-cost, high-yield and scalable single-step ball milling process is developed to construct 2D MoS₂/graphene hybrid electrodes for lithium-ion batteries. Electron microscopy investigation reveals that the obtained hybrid electrodes consist of numerous nanosheets of MoS₂ and graphene which are randomly distributed. The MoS₂/graphene hybrid anodes exhibit excellent cycling stability with high reversible capacities (442 mA h g⁻¹ for MoS₂/graphene (40 h); 553 mA h g⁻¹ for MoS₂/graphene (20 h); 342 mA h g⁻¹ for MoS₂/graphene (10 h)) at a high current rate of 250 mA g⁻¹ after 100 cycles, whereas the pristine MoS₂ electrode shows huge capacity fading with a retention of 37 mA h g⁻¹ at 250 mA g⁻¹ current after 100 cycles. The incorporation of graphene into MoS₂ has an extraordinary effect on its electrochemical performance. This work emphasises the importance of the construction of the 2D MoS₂/graphene hybrid structure to prevent capacity fading issues with the MoS₂ anode in lithium-ion batteries.

A solvent-free, low-cost, high-yield and scalable single-step ball milling process is developed to construct 2D MoS₂/graphene hybrid electrodes for lithium-ion batteries.     

Lychee-like TiO2@TiN dual-function composite material for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are promising candidates for next generation rechargeable batteries because of their high energy density of 2600 W h kg⁻¹. However, the insulating nature of sulfur and Li₂S, the “shuttle effect” of lithium polysulfides (LiPSs), and the volumetric change of sulfur electrodes limit the practical application of Li–S batteries. Here, lychee-like TiO₂@TiN hollow spheres (LTTHS) have been developed that combine the advantages of high adsorption TiO₂ and high conductivity TiN to achieve smooth adsorption/spread/conversion of LiPSs and use them as a sulfur host material in Li–S batteries for the first time. The cathode exhibits an initial specific capacity of 1254 mA h g⁻¹ and a reversible capacity of 533 mA h g⁻¹ after 500 cycles at 0.2C, which corresponds to an average coulombic efficiency up to 99%. The cell with the LTTHS@S cathode achieved an extended lifespan of over 1000 cycles. Such good performance can be assigned to the good adsorption and catalysis of the dual-function TiO₂@TiN composite. This work proved that the TiO₂@TiN composite can be an attractive matrix for sulfur cathodes.

Lithium–sulfur (Li–S) batteries are promising candidates for next generation rechargeable batteries because of their high energy density of 2600 W h kg⁻¹.     

Improved pseudocapacitive charge storage in highly ordered mesoporous TiO2/carbon nanocomposites as high-performance Li-ion hybrid supercapacitor anodes

A Li-ion hybrid supercapacitor (Li-HSCs), an integrated system of a Li-ion battery and a supercapacitor, is an important energy-storage device because of its outstanding energy and power as well as long-term cycle life. In this work, we propose an attractive material (a mesoporous anatase titanium dioxide/carbon hybrid material, m-TiO₂-C) as a rapid and stable Li⁺ storage anode material for Li-HSCs. m-TiO₂-C exhibits high specific capacity (∼198 mA h g⁻¹ at 0.05 A g⁻¹) and promising rate performance (∼90 mA h g⁻¹ at 5 A g⁻¹) with stable cyclability, resulting from the well-designed porous structure with nanocrystalline anatase TiO₂ and conductive carbon. Thereby, it is demonstrated that a Li-HSC system using a m-TiO₂-C anode provides high energy and power (∼63 W h kg⁻¹, and ∼4044 W kg⁻¹).

A mesoporous TiO₂/carbon nanocomposite prepared by block copolymer self-assembly improves pseudocapacitive behavior and achieves high energy/power density Li-ion hybrid supercapacitors.     

Rigid TiO2−x coated mesoporous hollow Si nanospheres with high structure stability for lithium-ion battery anodes

Rigid oxygen-deficient TiO_2−x coated mesoporous hollow Si nanospheres with a mechanically and electrically robust structure have been constructed through a facile method for high-performance Li-ion battery anodes. The mesoporous hollow structure provides enough inner void space for the expansion of Si. The oxygen-deficient TiO_2−x coating has functions in three aspects: (1) avoiding direct contact between Si and the electrolyte; (2) suppressing the outward expansion of the mesoporous hollow Si nanospheres; (3) improving the conductivity of the composite. The combined effect leads to high interfacial stability and structural integrity of both the material nanoparticles and the whole electrode. By virtue of the rational design, the composite yields a high reversible specific capacity of 1750.4 mA h g⁻¹ at 0.2 A g⁻¹, an excellent cycling stability of 1303.1 mA h g⁻¹ at 2 A g⁻¹ with 84.5% capacity retention after 500 cycles, and a high rate capability of 907.6 mA h g⁻¹ even at 4 A g⁻¹.

A conductive TiO_2−x shell suppresses the outward expansion of Si to maintain high interfacial stability and structural integrity.     

An anode catalyst support for polymer electrolyte membrane fuel cells: application of organically modified titanium and silicon dioxide

This work describes an attempt to improve the physical and electrochemical parameters of PEM fuel cells that have electrodes modified by titanium and silicon dioxides. A customized design of membrane electrode assemblies was proposed which is characterized to have an around 6 times higher concentration of catalyst at the cathode side (2.0 mgPt cm⁻²) in order to investigate the influence of anode catalyst support treatment. Anode catalyst support materials were modified using pristine TiO₂ and TiO₂–SiO₂–VTMS – the composite was crosslinked with the aid of vinyltrimethoxysilane. Surface area and porosity analysis was carried out with the aid of BET, BJH, t-plot and Horvath–Kawazoe (H–K) theories for particular components of the support materials and their catalyst mixtures. The experiment revealed a positive influence of TiO₂–SiO₂–VTMS (BET 321.9 m² g⁻¹, BJH 3.7 nm) on the anode catalyst layer in terms of surface area (3-times increase, 75 m² g⁻¹) and average pore size (decrease from 25.3 to 15.7 nm). Additionally, favourable microporosity (pores less than 2 nm) was introduced to the material according to the H–K analysis results (10.3 m² g⁻¹, 0.65 nm). Electrochemical experiments, which include polarization curves, electrochemical impedance spectroscopy and cyclic voltammetry, have demonstrated the change of behaviour for the fabricated fuel cells with modified anodes against the reference sample. The mitigation of charge and mass transfer resistance (by 15–20%, 50 mV at 200 mA cm⁻²), the improvement of power density (up to 72%, 217 mW cm⁻²) and a better exposure of the catalyst to the reactants of an electrochemical reaction were observed for fuel cells modified by both pristine TiO₂ and the hybrid TiO₂–SiO₂–VTMS-based compound.

TiO₂ and SiO₂ act successfully as an anode support material despite their poor electrical properties providing the improvement of fuel cell electrochemical parameters.     

Ultradispersed titanium dioxide nanoparticles embedded in a three-dimensional graphene aerogel for high performance sulfur cathodes

Lithium–sulfur (Li–S) batteries are regarded as one of the most promising energy storage technologies, however, their practical application is greatly limited by a series of sulfur cathode challenges such as the notorious “shuttle effect”, low conductivity and large volume change. Here, we develop a facile hydrothermal method for the large scale synthesis of sulfur hosts consisting of three-dimensional graphene aerogel with tiny TiO₂ nanoparticles (5–10 nm) uniformly dispersed on the graphene sheet (GA–TiO₂). The obtained GA–TiO₂ composites have a high surface area of ∼360 m² g⁻¹ and a hierarchical porous structure, which facilitates the encapsulation of sulfur in the carbon matrix. The resultant GA–TiO₂/S composites exhibit a high initial discharge capacity of 810 mA h g⁻¹ with an ultralow capacity fading of 0.054% per cycle over 700 cycles at 2C, and a high rate (5C) performance (396 mA h g⁻¹). Such architecture design paves a new way to synthesize well-defined sulfur hosts to tackle the challenges for high performance Li–S batteries.

GA–TiO₂ composites as a cathode material realize an excellent electrochemical performance in Li–S batteries.     

Design and synthesis of graphene/SnO2/polyacrylamide nanocomposites as anode material for lithium-ion batteries

Tin dioxide (SnO₂) is a promising anode material for lithium-ion batteries owing to its large theoretical capacity (1494 mA h g⁻¹). However, its practical application is hindered by these problems: the low conductivity, which restricts rate performance of the electrode, and the drastic volume change (400%). In this study, we designed a novel polyacrylamide/SnO₂ nanocrystals/graphene gel (PAAm@SnO₂NC@GG) structure, in which SnO₂ nanocrystals anchored in three-dimensional graphene gel network and the polyacrylamide layers could effectively prevent the agglomeration of SnO₂ nanocrystals, presenting excellent cyclability and rate performance. A capacity retention of over 90% after 300 cycles of 376 mA h g⁻¹ was achieved at a current density of 5 A g⁻¹. In addition, a stable capacity of about 989 mA h g⁻¹ at lower current density of 0.2 A g⁻¹ was achieved.

Tin dioxide (SnO₂) is a promising anode material for lithium-ion batteries owing to its large theoretical capacity (1494 mA h g⁻¹).     

Synthesis of a three-dimensional cross-linked Ni–V2O5 nanomaterial in an ionic liquid for lithium-ion batteries

A three-dimensional cross-linked Ni–V₂O₅ nanomaterial with a particle size of 250–300 nm was successfully prepared in a 1-butyl-3-methylimidazole bromide ionic liquid (IL). The formation of this structure may follow the rule of dissolution–recrystallization and the ionic liquid, as both a dissolution and structure-directing agent, plays an important role in the formation of the material. After calcination of the precursor, the active material (Ni–V₂O₅–IL) was used as an anode for lithium-ion batteries. The designed anode exhibited excellent electrochemical performance with 765 mA h g⁻¹ at a current density of 0.3 A g⁻¹ after 300 cycles, which is much higher than that of a NiVO–W material prepared via a hydrothermal method (305 mA h g⁻¹). These results show the remarkable superiority of this novel electrode material synthesized in an ionic liquid.

A three-dimensional cross-linked Ni–V₂O₅ nanomaterial with a particle size of 250–300 nm was successfully prepared in a 1-butyl-3-methylimidazole bromide ionic liquid (IL).     

Large-scale synthesis of ultrafine Fe3C nanoparticles embedded in mesoporous carbon nanosheets for high-rate lithium storage

Fe₃C modified by the incorporation of carbon materials offers excellent electrical conductivity and interfacial lithium storage, making it attractive as an anode material in lithium-ion batteries. In this work, we describe a time- and energy-saving approach for the large-scale preparation of Fe₃C nanoparticles embedded in mesoporous carbon nanosheets (Fe₃C-NPs@MCNSs) by solution combustion synthesis and subsequent carbothermal reduction. Fe₃C nanoparticles with a diameter of ∼5 nm were highly crystallized and compactly dispersed in mesoporous carbon nanosheets with a pore-size distribution of 3–5 nm. Fe₃C-NPs@MCNSs exhibited remarkable high-rate lithium storage performance with discharge specific capacities of 731, 647, 481, 402 and 363 mA h g⁻¹ at current densities of 0.1, 1, 2, 5 and 10 A g⁻¹, respectively, and when the current density reduced back to 0.1 A g⁻¹ after 45 cycles, the discharge specific capacity could perfectly recover to 737 mA h g⁻¹ without any loss. The unique structure could promote electron and Li-ion transfer, create highly accessible multi-channel reaction sites and buffer volume variation for enhanced cycling and good high-rate lithium storage performance.

Fe₃C modified by the incorporation of carbon materials offers excellent electrical conductivity and interfacial lithium storage, making it attractive as an anode material in lithium-ion batteries.