Search

Bimetallic sulfides display good electroconductibility and more redox active sites for sodium ion storage, which are expected to realize fast charging/discharging of sodium ion hybrid capacitors (SIHCs) integration. Herein, Sb was introduced into SnS2 on graphene (ATS/GNS) to enhance the kinetics of Na+ storage. The introduction of Sb at Sn site in SnS2 leads to a residual delocalized s electron and forms a half-filled and delocalized intermediate band, which can effectively improve electroconductivity. ATS possesses a high adsorption energy (-3.13 eV) and low diffusion energy barrier (0.26 eV) of Na+ by density functional theory calculations. ATS/GNS with remarkable stability possesses a reversible capacity of 507 mAh g−1 at 1 A g−1 after 3000 cycles. The ATS/GNS//N, S doped porous carbon SIHC delivers high energy/power densities (115 Wh kg−1/351 W kg−1 and 41 Wh kg−1/18750 W kg−1), and an excellent capacity retention of 70% after 10000 cycles at 5 A g−1. This work may present a feasible approach to design high-rate and long-term stability of sodium-based devices.

Layered transition-metal oxides have been extensively pursued as promising cathodes for sodium-ion batteries (SIBs) by virtue of their two-dimensional Na-diffusion channels and high theoretical capacities. Nevertheless, irreversible phase transitions, structural instability, and moisture sensitivity place obstacles in their way to approach higher performance. Aiming at tackling these challenging issues, an in-depth understanding of the structural evolutions, morphology changes, composition and valence variations, as well as the electrode/electrolyte interface reactions upon battery cycling is of vital importance. Current state-of-the-art characterization techniques can gain valuable insights into the elusive reaction mechanisms, yield an overall picture of the battery configurations, and provide a guideline for the design of new electrode materials. Herein, the latest progresses on the applications of advanced analytical techniques to probe the Na-storage layered oxide cathodes are comprehensively summarized. In-situ or operando techniques are highlighted in this review to directly link the real-time structure, morphology, composition information with the electrochemical response, and the electrochemical measurements are also mentioned in selected examples. Special attention is paid to the detection principle of each technique and what valuable information can be obtained. Finally, the future developments of layered oxides towards high-performance SIB cathode materials with the help of advanced diagnostic methods are well prospected.

Coupling metal oxides with heterostructured catalysts have been regarded as a promising strategy for promoting the hydrogen evolution reaction (HER). However, it remains a great challenge for optimal H adsorption and fast reaction kinetics. Herein, we fabricated few-layered MoN–MnO heterostructure catalysts implanted with interfacial-O configuration as synergistic sites. The unique structure promotes charge redistribution in the coupled boundary, which regulates the adsorption strength of H and synergistically interacts with nitrides for optimal H adsorption. Combined with a few-layered (5 layers, 3.5 nm) curved structure, the MoN–MnO electrode exhibits surpassed-Pt activity for HER under alkaline and neutral conditions. First-principles calculations indicate that the interfacial configuration is superactive and favorable for H adsorption. This work contributes to the understanding of heterostructured catalysts for promoting activity, and presents a new strategy to design interfacial engineering catalysts.

The intrinsically sluggish kinetics of the anodic oxygen evolution reaction (OER) is deemed to be the bottleneck for highly efficient electrocatalytic hydrogen production, and the by-product is less value-added oxygen. Herein, we report rational construction of Mo doped Co4N nanoarrays (Mo-Co4N) with an open skeleton structure as a robust bifunctional electrocatalyst for concurrent electrolytic high-purity hydrogen and value-added formate productions in the cathodic and anodic process. Benefitting from Mo doping, the unique structure characteristics of more exposed active sites, and optimized electronic synergy, Mo-Co4N exhibits intriguing hydrogen evolution reaction (HER) activity with an exceptionally small overpotential of 45 mV at 10 mA cm−2 and a low Tafel slope of 42 mV dec−1. Meanwhile, when the anodic partial methanol oxidation reaction (MOR) is used to replace the OER, the oxidation potential is significantly reduced to 1.356 V at 10 mA cm−2. In particular, a two-electrode electrolyzer employing Mo-Co4N as a bifunctional catalyst only requires an ultralow cell voltage of 1.427 V to achieve a current density of 10 mA cm−2, featuring low energy consumption in comparison to traditional overall water splitting. Furthermore, high Faraday efficiencies approaching 100% for hydrogen evolution and value-added formate production are achieved, as well as excellent 60 h long-term durability.

NaAlH4 is one of the most promising hydrogen storage materials due to its high energy density. However, the sluggish kinetic hindered it stepping into practical application. In this work, a bottom-up strategy was employed to confine NaAlH4 between graphene nanosheets with a millefeuille-liked multi-layer morphology. The NaAlH4 particles were uniformly arranged between graphene layers, with a high loading up to 90%, and performed improved dehydrogenation kinetic. The dehydrogenation peak temperature 55.7 °C decreased comparing with commercial NaAlH4. The generality of this nano-structuring strategy were confirmed by the successful synthesis of TiO2–NaAlH4 co-confined composites as well as the further enhanced kinetic.

The sodium super ionic conductor (NASICON) structured Na3MnTi(PO4)3 is attractive due to the eco-friendly and low-cost Na–Mn–Ti–P–O system. However, Na3MnTi(PO4)3 suffers from low Coulombic efficiency, inferior electronic conductivity and limited specific capacity basing on two-sodium-exchange. To address these multifaceted issues, herein, an interpenetrating graphene encapsulated Na3MnTi(PO4)3 particles with carbon-shell covering material (rGO@NMTP-C) was synthesized. By regulating cut-off voltages, a three-electron reaction was realized and Coulombic efficiency of the rGO@NMTP-C was found to increase from

To promote the electrochemical performance of a Li-rich layered cathode material Li1.2(Ni1/6Co1/6Mn4/6)0.8O2, the allogenic spinel@Li-rich (1 – y)[Li1.2(Ni1/6Co1/6Mn4/6)0.8O2]core·y[Lix(Ni1/6Co1/6M...

Aqueous alkali ion batteries attract increasing attention due to their merits of being safety, eco-friendly and low cost. Nevertheless, their development is hindered by the lack of suitable electrode materials with high capacity and cycling stability. As promising candidates, Prussian blue and its analogues (PBAs) are particularly attractive cathode materials in the energy storage field for their excellent electrochemical properties. Co-based PBAs (CoHCF) have relatively high discharge plateau, high theoretical capacity and good cycle performance. The potassium storage mechanism of CoHCF is still unclear and lacks study. Herein, a novel low-defect CoHCF was synthesized by a feasible coprecipitation method. When applied in aqueous potassium ion batteries (AKIBs), the two-electron-transfer process is observed clearly. The CoHCF electrode delivers a high reversible capacity of 83.6 mA h g−1 at a current density of 20 mA g−1 after 200 cycles. In addition, excellent rate performance and long cycling stability at 600 mA g−1 were obtained. The structural evolution and reaction mechanism of CoHCF upon K+ extraction/insertion were visibly characterized by ex situ X-ray diffraction and X-ray photoelectron spectroscopies. The results demonstrate a new strategy for the development of AKIB cathodes with excellent electrochemical performance.

Herein, the preparation of CoSb nanoparticles embedded in carbon nanofibers with a raised surface (N-doped CoSb@C nanofibers) via the electrospinning method is reported for the first time. The distinct structure facilitates the pseudocapacitive behaviors, which is the key to obtain fast kinetics and long cyclability. N and Co elements can not only optimize the electronic configuration but also buffer the volume changes of the material during cycling. For potassium-ion batteries, the capacity maintains 250 mA h g−1 after 500 cycles at 1 A g−1, and for sodium-ion batteries, the capacity keeps 413 mA h g−1 after 1000 cycles at 1 A g−1. Thus, this work makes a great contribution towards exploring high-capacity anodes for practical potassium-ion batteries and sodium-ion batteries.

Na2MnP2O7 has been considered as a promising cathode candidate for advanced sodium-ion batteries due to its high potential, low cost and non-toxicity. However, the low initial Coulombic efficiency, poor high-rate and unsatisfactory cycling ability originated from the intrinsic inferior electronic conductivity and manganese dissolution severely hinder its practical application. Herein, we report an approach based on a feasible high energy vibrating activation process to fabricate a robust graphene layers (GL) modified Na2MnP2O7 material (noted as NMP@GL) for the first time. The as-prepared NMP@GL could exhibit an ultrahigh initial Coulombic efficiency of 90%, and a high energy density over 300 Wh kg-1. In addition, rate performance and cycling stability were also improved, with high capacity retention of 83% after 600 cycles at 2 C. These impressive progresses should be ascribed to the enhanced electron transportation with distinctive framework through graphene layer modifying, and structural stability of triclinic Na2MnP2O7 with spacious 3D ion migration channels. Ex-situ XRD and GITT demonstrate a consecutive multi-phase reaction mechanism with facile sodium diffusion. Our design makes Na2MnP2O7@GL to achieve its potential for practical application.

Transition metal oxides have been regarded as the most potential anode material for lithium-ion batteries (LIBs), because of their high theoretical capacity, abundant resource, and low cost. Nevertheless, poor conductivity and large volumetric expansion during the charge–discharge processes make it difficult for LIBs application. In this work, we have adopted an in situ carbon coating method to synthesize 1D mesoporous MnO@C nanorods, which effectively work out the above problems of LIBs. Meanwhile, the MnO@C-3 (the mixture is 40 mL of H2O in solvothermal reaction) anode exhibits excellent rate capability with the capacity retention of 90.3% at 2.0 A g–1 and prominent cycling stability at 5.0 A g–1 with the discharge capacity of 1210.1 mAh g–1 after 400 cycles. When assembled to a full cell with commercial LiFePO4 as cathode, the full cell represents 360.7 mAh g–1 after 30 cycles (based on the anode), which displays a development potential for practical application.

Transition metal oxides possess eminently high capacity based on the conversion reaction by delivering multiple electrons. However, they usually demonstrate limited cycle life and inferior rate capability due to the pulverization and aggregation of active materials. V2O3 is considered to be an attractive electrode material due to its intrinsic tunnel structure provided by 3D V-V framework. Herein, a flexible and self-standing electrode of V2O3 nanoparticles embedded in porous N-doped carbon nanofibers (V2O3@PNCNFs) has been fabricated through a facile electrospinning method and subsequent thermal treatment. Electrochemical kinetic analysis, in situ XRD, ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculation suggest that the potassium storage of V2O3 is dominated by intercalation pseudocapacitance and only up to 1 mol K+ can insert into V2O3 crystal. Different from the conversion reaction in conventional transition metal oxides, in the mechanism of intercalation pseudocapacitance, K+ intercalate into the tunnels of V2O3 accompanied by a faradaic charge-transfer with no crystallographic phase change. This mechanism combines short charging/discharging times with long cycle life, which is reported in PIBs for the first time. This work may open up a new avenue for further development of pseudocapacitive nanomaterials for high-rate and ultra-stable energy storage.

We report an aqueous Zn–V2O5 battery chemistry employing commercial V2O5 cathode, Zn anode, and 3 M Zn(CF3SO3)2 electrolyte. We elucidate the Zn-storage mechanism in the V2O5 cathode to be that hydrated Zn2+ can reversibly (de)intercalate through the layered structure. The function of the co-intercalated H2O is revealed to be shielding the electrostatic interactions between Zn2+ and the host framework, accounting for the enhanced kinetics. In addition, the pristine bulk V2O5 gradually evolves into porous nanosheets upon cycling, providing more active sites for Zn2+ storage and thus rendering an initial capacity increase. As a consequence, a reversible capacity of 470 mAh g–1 at 0.2 A g–1 and a long-term cyclability with 91.1% capacity rentention over 4000 cycles at 5 A g–1 are achieved. The combination of the good battery performance, safety, scalable materials synthesis, and facile cell assembly indicates this aqueous Zn–V2O5 system is promising for stationary grid storage applications.

Designing the hydrogen evolution reaction (HER) electrocatalysts by tuning the micro/nano structure and optimizing composition to overcome the sluggish HER kinetics have fueled intensive research interests in recent years. Herein, the Co and CoP nanograins embedded in porous nitrogen-doped carbon nanofibers (Co/CoP@NC) are prepared by a controllable electrospinning method and subsequent thermal treatments as the wide-pH HER electrocatalysts. Owning to the prominent merits of strong synergistic relationships between Co and CoP nanoparticles, N-doped carbon configuration, and the interconnected three dimensional (3D) porous carbon network, the Co/CoP@NC nanofibers exhibit robust HER activity with affording an overpotential of 117 mV in acidic and 180 mV in alkaline media to deliver the current density of 10 mA cm-2. As a practical application, when integrated the Co/CoP@NC/Ni foam cathode with the NiFe layered double hydroxides/Ni foam anode (NiFe-LDH/Ni foam), the electrolyzer can afford the cell voltage of 1.62 V to deliver the current density of 10 mA cm-2, as well as ultralong lifetime of 60 h in alkaline medium, providing a viable alternative to the noble-metal electrocatalysts for water splitting.

Developing durable, nonprecious hydrogen evolution reaction (HER) electrocatalysts with Pt-like performance is desirable but remains challenging. Here we report a one-step electroless synthesis of an amorphous Co2.90B0.73P0.27 ternary alloy and its application as a new highly active and robust HER catalyst. The synthesized Co2.90B0.73P0.27 nanosheets supported on Ni foam exhibit remarkable catalytic performance in alkaline media, delivering a low onset overpotential of 12 mV and a low Tafel slope of 42.1 mV dec−1. Moreover, this self-supported monolithic electrode sustains a high current density of 1000 mA cm−2 and extended polarization over 20 h, outperforming the Pt/C benchmark. The superior performance is attributed to the superhydrophilic properties of the nanosheet microstructure and the synergistic effect of elements P and B, which favors dissociation of H2O, weakens surface H absorption, and suppresses Co oxidation. This work provides a new avenue for the design and optimization of transition metal boron phosphides for HER electrocatalysis.

Sulfur is a promising alternative lithium battery cathode for its low cost, abundance, and high specific capacity. However, issues of rapid capacity decay and low coulombic efficiency hamper its practical application pace owing to polysulfides dissolution. Despite efforts on hybridizing sulfur with metal oxides to solve these issues are considered to be effective, the synthesis of hybrid materials is always tedious. Herein, S@MnO2 hybrid material was synthesized via a green method at room temperature. We encapsulate S spheres in poly-dopamine (PDA) by in-situ polymerization of dopamine. The formed PDA shell is served as reducing agent and sacrificial template to transform KMnO4 into δ-MnO2 shell without adding any other agents (such as acid). δ-MnO2 encapsulates the S spheres uniformly and succeeded in entrapping polysulfides when S@MnO2 used for Li–S battery, endowing the S@MnO2 cathode with high reversible capacity, improved cycling stability, and satisfied coulombic efficiency. Moreover, this method could be adopted for hybridizing δ-MnO2 with diverse materials (such as CNTs@MnO2) in mild reaction environment (ambient pressure and temperature), exhibiting an extensive application on constructing Mn-based oxide hybrid functional materials.

In this paper, red phosphorus nanoparticles (~ 97.7 nm, 51 wt% content) homogeneously embedded in porous nitrogen-doped carbon nanofibers (denoted as P@C) are prepared using a feasible electrospinning technique for the first time. Meanwhile, red P@C with the character of free-standing membrane is directly used as binder- and current collector-free anode for sodium-ion batteries, exhibiting a highly reversible three-electron transfer reaction (3Na + + P + 3e - ↔ Na 3 P) with excellent rate capability (1308 mA h g -1 at 200 mA g -1 in comparison of 343 mA h g -1 at 10,000 mA g -1 ) and remarkable cyclic stability (~ 81% capacity retention after 1000 cycles). Furthermore, a soft package Na-ion full battery with red P@C anode and Na 3 V 2 (PO 4 ) 2 F 3 /C cathode is assembled, displaying a high operation voltage of ~ 3.65 V and an outstanding energy density of 161.8 W h kg -1 for the whole battery. This is owing to the distinctive structure of very small amorphous phosphorus nanoparticles uniformly confined in porous N-doped carbon nanofibers, which can effectively facilitate the electronic/ionic transportation and retard the active materials pulverization/fracture caused by volume fluctuation upon prolonged cycling. The simple and scalable synthesis route as well as the promising electrochemical performance shed new insights into the quest for high energy and long life phosphorus-based Na-storage anode materials.

The dehydrogenation behavior of LiBH4 has been investigated when confined into porous NiMnO3 microsphere via a wet chemical impregnation method. The confinement of LiBH4 in the pores of NiMnO3 nanoparticles leads to a significant decrease of the onset and the maximum desorption temperatures. The composites begin to release hydrogen at 150 °C and the maximum desorption temperature is 300 °C, which are much lower compared to the raw LiBH4. Also, the hydrogen release amount is found to be increased. Moreover, the LiBH4@NiMnO3 composites exhibit excellent dehydrogenation kinetics, with 2.8 wt% hydrogen released in 1 h at 300 °C. X-ray diffraction and Fourier transform infrared spectroscopy are used to deduce the desorption mechanism of NiMnO3.

Potassium-ion batteries (KIBs) are considered to be promising energy-storage-systems in the post-Li-ion batteries. Conversion and alloy reaction anode materials draw much attention owing to high theoretical capacities. However, their inherent volume expansions always block the K-ion diffusion or interrupt electron transfer to a degree, resulting in degraded performances at high rates. It is supposed that the rate capability of the anode would be improved when the avenues for ion/electron are kept expedite simultaneously. Herein, SnS2 and carbon hybrid submicro-fibers with optimized channels were prepared as integrated KIBs electrodes to clarify the effect of the bi-continuous avenues on the rate capability. In this configuration, SnS2 nanosheets are confined by carbon and further crosslinked into 3D network. The 3D carbon submicro-fibers are adopted as a network for electron transfer, while the channels play the role of ion diffusion avenues. Owing to the stable and expedite bi-continuous electron/ion avenues, the rate capability of the SnS2@C–1V1 SMF electrode (137.5 mAh g−1 at 2.0 A g−1) is improved when compared to the counterparts (3.6 mAh g−1 and 94.5 mAh g−1 at the same condition). This work will offer an important reference for the optimization design and construction of KIBs anode materials with high rate capability.

The nanoscaled Ni-based compounds (Ni 3 C, Ni 3 N, NiO and Ni 2 P) are synthesized by chemical methods. The MgH 2 -X (X = Ni 3 C, Ni 3 N, NiO and Ni 2 P) composites are prepared by mechanical ball-milling. The dehydrogenation properties of Mg-based composites are systematically studied using isothermal dehydrogenation apparatus, temperature-programmed desorption system and differential scanning calorimetry. It is experimentally confirmed that the dehydrogenation performance of the Mg-based materials ranks as following: MgH 2 Ni 3 C, MgH 2 Ni 3 N, MgH 2 NiO and MgH 2 Ni 2 P. The onset dehydrogenation temperatures of MgH 2 Ni 3 C, MgH 2 Ni 3 N, MgH 2 NiO and MgH 2 Ni 2 P are 160 °C, 180 °C, 205 °C and 248 °C, respectively. The four Mg-based composites respectively release 6.2, 4.9, 4.1 and 3.5 wt% H 2 within 20 min at 300 °C. The activation energies of MgH 2 Ni 3 C, MgH 2 Ni 3 N, MgH 2 NiO and MgH 2 Ni 2 P are 97.8, 100.0, 119.7 and 132.5 kJ mol −1 , respectively. It' found that the MgH 2 Ni 3 C composites exhibit the best hydrogen storage properties. Moreover, the catalytic mechanism of the Ni-based compounds is also discussed. It is found that Ni binding with low electron-negativity element is favorable for the dehydrogenation of the Mg-based composites.

To enhance the electronic conductivity of TiO 2 , carbon-coating has been used as a simple and effective method for improving the electrochemical performances of TiO 2 in sodium ion batteries. In this work, considering the internal connection between TiO 2 and the coated carbon-layer, we synthesized carbon-coated TiO 2 composites (TiO 2 /C) via hydrothermal method and subsequent calcination, assisted with different types of surfactant as carbon sources. Due to strong electrostatic attraction, cationic surfactant CTAB (cetyltrimethyl ammonium bromide) generates a uniformly-coated carbon layer onto TiO 2 surface, which enables good electronic conductivity and fast kinetics of the product. Therefore, TiO 2 /C assisted with CTAB as carbon source (TiO 2 /C-C) shows optimal sodium storage performance with excellent specific capacity (303 mA h g −1 at 0.1 C) and satisfying cycling stability, offering promising anode for constructing high capacity sodium ion batteries.

LiBH4@xZZCO composites are successfully synthesized by confining LiBH4 in hierarchical porous ZnO/ZnCo2O4 (ZZCO) nanoparticles via a chemical impregnation method, and the effect of ZZCO on the dehydrogenation performance is systematically investigated. It is found that dehydrogenation properties of LiBH4 are significantly improved, especially for the LiBH4@2ZZCO composite. The onset desorption temperature of LiBH4@2ZZCO is decreased to 169 °C, and the majority of hydrogen release occurs at 275 °C, much lower than raw LiBH4. In addition, 8.7 wt% H2 could be released below 500 °C. Moreover, the apparent activation energy (Ea) has been reduced from 146 kJ/mol (pure LiBH4) to 120.22 kJ/mol. The improved dehydrogenation properties are attributed to the synergistic effect of nanoconfinement and destabilization of ZZCO nanoparticles.

In this paper, we report the synthesis of graphene-like MoS2/graphene hybrid by a facile lithium-assisted sonication method and its cathode application for rechargeable Mg batteries. Instrumental analyses elucidate that the composite displays a three-dimensional (3D) porous architecture constructed by exfoliated single or few MoS2 layers, and some graphene is intercalated in the MoS2 gallery with an enlarged interlayer spacing from 0.62 to 0.98 nm. The obtained MoS2/graphene hybrid exhibits high electrochemical performance with a remarkable capacity (115.9 mA h g−1) and good cyclic stability (82.5 mA h g−1 after 50 cycles). This is owing to the synergistic effect between the graphene-like MoS2 and the highly conductive graphene, which can effectively facilitate the Mg2+ ions diffusion and electrons transfer, provide abundant active sites for Mg2+ intercalation, and prevent structural collapse upon prolonged cycling.

Graphene monolayers or bilayers highly scattered in porous carbon nanofibers (denoted as G/C) are first prepared by a feasible electrospinning technique. Meanwhile, G/C with the character of a flexible membrane adherent on copper foil is directly used as binder-free anode for Na-ion batteries, exhibiting fascinating electrochemical performance in terms of high reversible capacity (432.3 mA h g−1 at 100 mA g−1), exceptional rate capability (261.1 mA h g−1 even at 10 000 mA g−1), and ultra-long cycling life (91% capacity retention after 1000 cycles). This is due to the synergistic effect between the highly exfoliated graphene layers and the porous carbon nanofibers, which can provide massive active Na-storage sites, ensure sufficient electrolyte infiltration, offer open ionic diffusion channels and oriented electronic transfer pathways, and prevent graphene agglomeration as well as carbon nanofiber fracture upon prolonged cycling. The findings shed new insights into the quest for high-performance carbon-based anode materials of sodium-ion batteries.

Sodium-ion batteries (SIBs) have been considered as a potential large-scale energy storage technology (especially for sustainable clean energy like wind, solar, and wave) owing to natural abundance, wide distribution, and low price of sodium resources. However, SIBs face challenges of low specific energy, unsatisfactory rate capability, and short cycling life caused by the heavy mass and large radius of Na+ ions. Therefore, developing promising host materials with the ability of fast, stable, and efficient sodium-ion insertion/extraction is key to promoting SIBs. Furthermore, the optimization of the electrolyte, the matching of cathode and anode materials, and the construction of sodium-ion full batteries with high-performance, high-safety, and low cost are urgently needed in order to make SIBs commercially available. In this review, we summarize the up-to-date research progress and insights on key materials (including cathode, anode, and electrolyte) for Na storage and some representative Na-ion full battery configurations will also be emphatically described. This should shed light on the fundamental research and practical applications of sodium-ion batteries.

Nitrogen-doped hierarchically porous carbon (NHPC) materials have been synthesized by using a zeolitic imidazolate framework, ZIF-8, as self-sacrificing template. The initial derived carbon (D-carbon) contains a 3-dimensional (3D) hierarchically porous carbon framework with rich nitrogen doping (11.22%). Chemical activation by KOH, the further activated carbon (Ac-carbon) shows a specific high surface area (2477 m 2 g −1 ), but lower N content (1.99%). LiBH 4 -(D-carbon)/(Ac-carbon) is prepared by ball-milling method and the dehydrogenation performance of LiBH 4 is significantly improved. More than 6.13 wt% H 2 can be released from either of the two mixtures within 100 min at 320 °C, respectively, showing better dehydrogenation performance than that of pure LiBH 4 . Additionally, the controlled experiments reveal that those improved dehydrogenation properties of LiBH 4 might be attributed to the synergetic contributions of high N heteroatom loading, large surface area and catalysis of carbon materials. We provided a simple method to prepare solely MOF-derived nitrogen-doped carbon materials, which might be a promising catalyst for the hydrogen storage materials.

Ni2P/GNS nanocomposite was synthesized by a facile and green hydrothermal technique. Microstructural characterizations demonstrated that Ni2P nanoparticles with an average size of about 5 nm were uniformly distributed in graphene nanosheets. The Ni2P/GNS nanohybrid exhibited enhanced effects on the dehydrogenation properties of MgH2 compared to Ni2P and GNS individually. The onset desorption temperature of MgH2 Ni2P/GNS composite reduced by 98 °C in contrast with the pure as-milled MgH2. Moreover, the MgH2 Ni2P/GNS composite could release 6.1 wt% H2 (only 0.2 wt% H2 for the pure as-milled MgH2) within 20 min at 325 °C. In addition, the relative hydrogen desorption mechanism of MgH2 Ni2P/GNS composite has also been discussed.

We report on the preparation of the three dimensional (3D) network structure CuO by rapid and facile engraving method and their application as high rate anode for sodium ion battery. The CuO is rapidly synthesized by in-situ etched and oxidated the specified Cu foils within 15 min. It shows the 3D network architecture with flower-like nanosheets connected by nanowires, which provides the porous structure, short ion diffusion pathway and collaborative electronic transmission. Furthermore, the etched CuO can be directly used as anode for sodium ion battery without polymer additions or conductive agents. The electrodes exhibit excellent electrochemical performance with a high capacity of 680 mAh·g −1 at 50 mA g −1 and a reversible capacity of 280 mAh·g −1 at 1000 mA g −1 . In addition, the electrochemical reaction and detail charge/discharge process are carefully explored to discover the conversion reaction routes and the recession reason. Thus, the 3D network structure CuO might open an insight for transition-metal oxides as energy storage materials.

We report on the strategy of Cu doping inducing the nanosize effect of CoO and their application as anode for lithium ion batteries. With an increase of Cu-doped amount, the structures and morphologies of CoO have special changes. The 0.05 mol Cu-doped CoO shows straw-like bundle structure assembled by nanorods, and the nanorods consist of ultra small nanoparticles (about 6–8 nm). Meanwhile, it shows an excellent rates performance and cycle life. The capacity of 800 mA h g−1 is obtained at 0.5 C after 80 cycles. The highest discharge capacity is 580 mA h g−1 at 10 C and the discharge capacities are relatively stable for 1000 cycles as an anode for Li-ion battery. Therefore, the controllable Cu-doped CoO composite could be deemed to be a potential candidate as an anode material.

Hierarchical porous ZnO/ZnCo2O4 (denoted as ZZCO) nanosheets have been successfully synthesized by one-step thermal annealing of the as-prepared Zn–Co-MOF precursor. The ZZCO nanosheets are composed of uniform sized, interconnected primary ZnO and ZnCo2O4 (donated as ZCO) nanoparticles (NPs), which are homogeneously dispersed in the products. Moreover, it possesses favorable features, such as a three-dimensional hierarchical nanosheet structure for fast charge transfer, high porosity from the MOF and good structural stability. This hierarchical porous ZZCO nanohybrid is found to be very attractive for lithium-ion batteries. A reversible capacity of 1016 mA h g−1 was maintained after a repetitive 250 cycles at 2 A g−1 with a remarkable coulombic efficiency of almost 99% and even when the current was 10 A g−1, a capacity of 630 mA h g−1 was attained. The excellent electrochemical performance should be due to the advantageous structural and compositional features.

An advanced asymmetric supercapacitor device (ASC) with high energy density was successfully fabricated by using a three-dimensional (3D) core–shell Ni@C hybrid as the positive electrode and activated carbon (AC) as the negative electrode. In addition, the Ni@C hybrid exhibited a one-dimensional (1D) morphology as a whole and a 3D core–shell nanostructure in details. The Ni@C hybrid was subtly controlled down to 10 nm scale to achieve a large exposed exterior surface and a remitting diffusion-controlled ion transference process. Moreover, the 1D porous texture and Ni-decoration of the Ni@C hybrids improved the supercapacitive performance enormously, with an ultrathin carbon shell ensuring a large external active surface and high electrical conductivity. Due to its unique core–shell structure, the Ni@C hybrid electrode delivered a high 2006 F g−1 capacitance at 1 A g−1, and still retained a high 1582 F g−1 capacitance with the current density increasing up to 20 A g−1. Coupled with the AC negative electrode, the ASC device delivered a 152.7 F g−1 capacitance at 1 A g−1 and 99 F g−1 at 10 A g−1. The capacitance retention reached up to 91% after 2000 cycles at a 1 A g−1 current density. In addition, the ASC device delivered a maximum 61.3 W h kg−1 energy density with a 1.6 V operational voltage, which could remain at 39.8 W h kg−1 even at a 1.12 kW kg−1 power density, suggesting promising future applications.

In this work, 3D hierarchical flower-like MoS 2 spheres are successfully fabricated via a hydrothermal method followed by a heat treatment. The obtained product is composed of few-layered MoS 2 nanosheets with enlarged interlayer distance (ca. 0.66 nm) of the (002) plane. Meanwhile, the hydrogen storage properties of the as-prepared MoS 2 ball milled with LiBH 4 are systematically investigated. The results of temperature programmed desorption (TPD) and isothermal measurement suggest that the LiBH 4 –MoS 2 (as-prepared) mixture exhibits favorable dehydrogenation properties in both lowering the hydrogen release temperature and improving kinetics of hydrogen release rate. LiBH 4 –MoS 2 (as-prepared) sample (the preparation mass ratio is 1:1) starts to release hydrogen at 171 °C, and roughly 5.6 wt% hydrogen is released within 1 h when isothermally heated to 320 °C, which presents superior dehydrogenation performance compared to that of the bulk LiBH 4 . The excellent dehydrogenation performance of the LiBH 4 –MoS 2 (as-prepared) mixture may be attributed to the high active site density and enlarged interlayer distance of the MoS 2 nanosheets, 3D architectures and hierarchical structures.

A facile two-step annealing process is applied to synthesize nanocage Co3O4, using cobalt-based metal-organic framework as precursor and template. The as-obtained nanocages are composed of numerous Co3O4 nanoparticles. N2 adsorption–desorption isotherms show that the as-obtained Co3O4 has a porous structure with a favorable surface area of 110.6 m2 g−1. Electrochemical tests show that nanocage Co3O4 is a potential candidate as anode for lithium-ion batteries. A reversible specific capacity of 810 mAh g−1 was obtained after 100 cycles at a high specific current of 500 mA g−1. The material also displays good rate capability, with a reversible capacity of 1069, 1063, 850, and 720 mAh g−1 at specific current of 100, 200, 800, and 1000 mA g−1, respectively. The good electrochemical performance of nanocage Co3O4 can be attributed to its unique hierarchical hollow structure, which is maintained during electrochemical cycling.

Fabricating electrode with hierarchical heterostructure is an effective method to incorporate the merits of different active materials into an electrode with desired electrochemical performance. However, heterostructure electrodes constructed layer by layer may increase the ion diffusion distances inadvertently when used for alkali metal ion batteries, though the synergistic effects of the components are exhibited. In this work, Co3O4 nanocrystallines (about 5 nm) anchor on ultrathin MnO2 nanosheets, which assemble hierarchical heterostructure hollow spheres (named as MnO2/Co3O4). When used as LIBs anode, the different dimensions of the components in MnO2/Co3O4 make them accessible for the electrolyte synchronously, without enlarging the ion diffusion distance. Moreover, the unique hierarchical hollow structure mitigates the internal mechanical stress brought by the volume variations upon cycling, preventing the electrode collapse. Therefore, the as-prepared MnO2/Co3O4 electrode not only delivers a high reversible capacity of 1209.0 mAh g−1 at 0.4 A g −1 over 300 cycles, but also exhibits long cyclic stability (a capacity of 581.8 mAh g−1 at 2.0 A g−1 after 1100 cycles). This work could provide new insight into heterostructure materials for batteries.

A new recycling way for simply recovered LiCoO2 materials from spent Li-ion batteries (LIBs) is proposed to serve as a high-performance supercapacitor material in aqueous systems for the first time. A solvent method, using inexpensive DMF to recover the waste LiCoO2 scraps, is suitable for industrial large-scale application with the prominent characteristics of low cost and simple technique. The recovered LiCoO2 sample displays the maximum capacitances of 654 F g–1 with a capacity retention rate of 86.9% after 4000 cycles at 2 A g–1. Excellent electrochemical capacitive behaviors demonstrate that the recovered LiCoO2 material is a promising candidate for pseudocapacitors, which could overcome not only the serious resource waste and environment contamination of LiCoO2 materials in spent LIBs but also the high-cost restriction of supercapacitor practical applications. So, it is hopeful for the recovered LiCoO2 material to be used in supercapacitors, which has advantages of high power density, cost-effective...

In this paper, the novel Cu@CoNi tri-metallic core-shell NPs have been synthesized by a facile and efficient in situ method at room temperature. It exhibits superior catalytic activity towards the hydrolysis dehydrogenation of ammonia borane (NH 3 BH 3 , AB). In these series nanoparticles, the Cu 0.4 @Co 0.5 Ni 0.1 core-shell NPs showed the best catalytic performance that the maximum hydrogen generation rate is 7340.80 mL min −1 g −1 at 298 K. The hydrolysis reaction towards AB was proved to the first order by the Cu 0.4 @Co 0.5 Ni 0.1 NPs via kinetic studies. The activation energy was 36.08 kJ mol −1 . Even after five recycle experiment, the catalysts also showed a good recycle stability in aqueous solution owing to the synergistic effect of Cu, Co and Ni in the tri-metallic core-shell NPs. The core-shell NPs/carbon composites also showed the better catalytic performance for hydrolysis to ammonia borane and rGO is proved to be the best support to catalyst.

Mesoporous zinc cobaltite (ZnCo 2 O 4 ) microspheres have been successfully prepared by a facile solvothermal method followed by an annealing process. The as-prepared ZnCo 2 O 4 displays uniform sphere-like morphology composed of interconnected ZnCo 2 O 4 nanoparticles. The Brunauer–Emmett–Teller (BET) surface area of mesoporous ZnCo 2 O 4 microspheres is about 51.4 m 2 g −1 with dominant pore diameter of 7.5 nm. The novel ZnCo 2 O 4 material exhibits high specific capacitance of 953.2 F g −1 and 768.5 F g −1 at discharge current densities of 4 A g −1 and 30 A g −1 , respectively. The energy density can be estimated to be 26.68 Wh kg −1 at a power density of 8 kW kg −1 . The specific capacitance retention is 97.8% after 3000 cycles, suggesting its excellent cycling stability. The superior electrochemical performance is mainly attributed to the uniformity of the surface structure and the porosity of the microspheres, which benefit electrons and ions transportation, provide large electrode-electrolyte contact area, and meanwhile reduce volume change during the charge–discharge process. This method of constructing porous microspheres is very effective, yet simple, and it could be applied in other high-performance metal oxide electrode materials for electrochemical capacitors, as well as in Li-ion batteries.

Small amount of reduce graphene oxide (rGO) nanosheets modified Li 4 Ti 5 O 12 nanoparticles composite has been synthesized by a facile and environmental in-situ hydrothermal reaction with subsequent annealing. The small amount of rGO (only 1.2 wt. %) greatly improves the whole morphology and electrochemical performance of composite. The nanoparticles uniformly grow on the rGO nanosheets effective suppressing the agglomeration and enhancing the specific surface area. Meanwhile, the special discharge capacity is 187 mAh g −1 at 1 C and the high rates discharge capacity is 128 mAh g −1 at 80 C (discharge-charge time only 33s). In particular, the cells remain in good work condition after 2000 cycles at 80 C, which credibly evidence the excellent electrochemical performance as an anode for high-power LIBs.