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Due to the unique safety qualities, solid composite polymer electrolyte (SCPE) has achieved considerable attentions to fabricate high-energy-density lithium metal batteries, but its overall performance still has to be improved. Herein, a high lithium salt content poly(vinylidene fluoride) (PVDF)-based SCPE was developed, enhanced by hexagonal boron nitride (h-BN) nanosheets, presenting perfect electrochemical performance, fast ion transport, and efficient inhibition of lithium dendrite growth. The optimized SCPE (PVDF-L70-B5) could deliver high ionic conductivity (2.98×10

The application of lithium metal anode with high specific capacity and energy density is limited by the volume expansion and pulverization caused by dendrite growth during cycle process. We propose a composite lithium anode by immersing molten lithium on the flexible three-dimensional (3D) carbon cloth scaffold with the zinc nanoparticles. The lithiophilic zinc nanoparticles layer of framework is synthesized by fast and easy electrochemical deposition from ionic liquid avoiding high temperature, high pressure and toxic reagent. The lithium is infused into the 3D lithiophilic framework, the composite anode is obtained. The steady network structure can confine the lithium and lead to Li dendrite restraining and reducing volume change due to the low interfacial resistance and reduce the effective current density, which induced the homogeneous Li growth. Benefiting from this, the Li infused 3D carbon cloth-Zn symmetric battery exhibits a low stripping/plating overpotential (~30 mV) and can be stable over 900 h at 1 mA cm−2. The Li//LiFePO4 battery delivers higher reversible capacity (140 mAh g−1 at 2 C and 120 mAh g−1 at 5 C) and stable cycling for 1500 and 2000 cycles than bare Li.

Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their high energy density (2600 Wh kg−1). However, its commercialization is hindered seriously by the low loading and utilization rate of sulfur cathodes. Herein, we designed the cellulose-based graphene carbon composite aerogel (CCA) self-standing electrode to enhance the performance of Li-S batteries. The CCA contributes to the mass loading and utilization efficiency of sulfur, because of its unique physical structure: low density (0.018 g cm−3), large specific surface area (657.85 m2 g−1), high porosity (96%), and remarkable electrolyte adsorption (42.25 times). Compared to Al (about 49%), the CCA displayed excellent sulfur use efficiency (86%) and could reach to high area capacity of 8.60 mAh cm−2 with 9.11 mg S loading. Meanwhile, the CCA exhibits the excellent potential for pulse sensing applications due to its flexibility and superior sensitivity to electrical response signals.

Here we prepare a hexagonal boron nitride (h-BN)–polyethylene oxide composite polymer electrolyte via a convenient casting method, which shows high mechanical strength. Meanwhile, the electrochemical properties (electrochemical window and lithium ion transference number) are enhanced but the ionic conductivity of the h-BN composite electrolyte is decreased after adding h-BN. Density functional theory (DFT) calculation results show that a stronger binding effect is observed between TFSI− and BN, compared to that between Li+ and BN. Molecular dynamics (MD) simulations are also utilized to study the mechanism behind the enhanced Li ion diffusion by h-BN addition. Li+ diffusion in PEO/LiTFSI/BN is lower than that in the PEO/LiTFSI system, but the diffusion of TFSI− exhibits a more significant decline rate in the presence of BN. This indicates that the presence of BN suppresses anion motion and enhances selectivity in Li+ transport. Thus, the PEO/LiTFSI/h-BN composite electrolyte exhibits higher Li ion conductivity but lower anion diffusivity than the PEO/LiTFSI system. Hence the h-BN composite polymer electrolyte in a Li/Li symmetric battery provides a long cycling time of 430 h at 0.2 mA cm−2. A Li metal/LiFePO4 full battery with the PEO/LiTFSI/h-BN composite electrolyte also works more efficiently for long-term cycling (140 cycles) than a filler-free PEO based electrolyte (39 cycles).

A solid polymer electrolyte is expected to be useful for safe and high energy density lithium-metal batteries owing to its good flexibility and high degree of safety. The development of a polyethylene oxide (PEO) based solid electrolyte is still restrained by low ionic conductivity and unsatisfactory mechanical strength. Since MnO2 could combine with PEO chains and Li ions could undergo long-range migration on MnO2 nanosheets, MnO2 nanoflakes are chosen as fillers to improve the electrochemical and mechanical properties of a solid polymer electrolyte. A PEO/MnO2 composite solid polymer electrolyte (CSPE) displays a higher lithium ion transference number (0.378), higher ionic conductivity (1.5 times higher at 60 °C) and better tensile strength (2.3 times) than a PEO solid electrolyte. Density functional theory calculations reflect the fact that the binding energy between the PEO/Li complex and MnO2 is small and there is easy desorption of Li from PEO and migration on MnO2 nanosheets, indicating enhanced lithium ion transport in the electrolyte system. A solid-state lithium metal battery using a PEO/MnO2 CSPE delivers higher capacity (143.5 mA h g−1 after 300 cycles) than an electrolyte without fillers (61.2 mA h g−1 after 90 cycles). Soft-package lithium metal batteries with an MnO2 CSPE reveal high safety after cutting, nail and bending tests.

The electrocatalytic nitrogen reduction reaction (NRR) is a promising strategy to generate NH3 in mild condition. Herein, we designed four NRR single-atom catalysts to mimic the structures of FeMo-cofactor in nitrogenase, in which a Mo or Fe atom is anchored to sulfur doped graphene carbon nanosheets (Mo/Fe@S-gCNS). Density functional theory calculations were performed to investigate the stability of Mo/Fe@S-gCNS, as well as their NRR activity. The results suggest that Mo@S-gCNS coordinated with three S (Mo-S3) displays the best NRR catalytic activity among the four catalysts, and the NRR prefers to proceed through the enzymatic pathway with an overpotential as low as 0.24 V. The outstanding performance is mainly attribute to the appropriate coordination environment together with the intrinsic electronic structure of the embedded Mo atom. These findings contribute to designing the NRR single-atom catalysts and understanding the potential active sites of the FeMo-cofactor.

Currently, even though birefringent soft materials have attracted considerable attention for many sensors and optical devices, it is still difficult for most of them to achieve multiple responses. Herein, we have designed a multiple-responding birefringent elastomer with high birefringence but low modulus by using 2-phenoxy-ethanoacrylate (PHEA) as monomer and 4-cyano-4'pentylbiphenyl as solvent. The excellent transparency (~90%) exhibited by the designed birefringent elastomer allowed us to observe the change of interference color. The obtained birefringent elastomer not only can be used as a photoelastic strain sensor with high sensitivity and fast response but also show a very sensitive response to heat, particularly in the range of the human body temperature. More interestingly, it shows excellent dielectric properties with a strong correlation between the interference color and the applied electric field, which allows easily writing and erasing the encrypted information. These unique multi-signal response features of our obtained birefringent elastomer shed light on the multiple information encryptions, the anti-counterfeiting, and the multifunctional sensors.

The photoelastic effect has many uses in mechanics today, but it is usually disregarded in flexible materials. Using 2-phenoxyethyl acrylate as a monomer and 4-cyano-4'-pentylbiphenyl (5CB) as a solvent, a multiple responsive photoelastic organogel (PO) with strong birefringence but low modulus is created. 5CB is a liquid crystal molecule that does not participate in the polymerization process and is always present as tiny molecules in the polymer. It endows the PO low modulus and high birefringence, as well as the ability to drive the birefringence using an electric field. This PO not only has high sensitivity and fast response as a photoelastic strain sensor, but also has a very sensitive response to heat, especially in the range of human body temperature. It also has a high dielectric constant and a strong correlation between the interference color and the applied electric field, allowing for easy writing and erasure of encrypted data. This unique multisignal response feature and low modulus that mimics human skin bring up new opportunities in the potential applications such as multiple information encryption, anticounterfeiting, and multifunctional wearable sensors.

© 2019 Sodium-ion batteries (SIBs) are considered as a promising candidate to lithium-ion batteries (LIBs) owing to the inexpensive and abundant sodium reserves. However, the application of anode materials for SIBs still confront rapid capacity fading and undesirable rate capability. Here we simultaneously grow ultrafine ZnSe nanoparticles on the inner walls and the outer surface of hollow carbon nanospheres (ZnSe@HCNs), giving a unique hierarchical hybrid nanostructure that can sustain a capacity of 361.9 mAh g −1 at 1 A g −1 over 1000 cycles and 266.5 mAh g −1 at 20 A g −1 . Our investigations indicate that the sodium storage mechanism of ZnSe@HCNs electrodes is a mixture of alloying and conversion reactions, where ZnSe converts to Na 2 Se and NaZn 13 through a series of intermediate compounds. Also, a full cell is constructed from our designed ZnSe@HCNs anode and Na 3 V 2 (PO 4 ) 3 cathode. It delivers a reversible discharge capacity of about 313.1 mAh g −1 after 100 cycles at 0.5 A g −1 with high Columbic efficiency over 98.2%. The outstanding sodium storage of as-prepared ZnSe@HCNs is attributed to the confinement of ZnSe structural changes both inside/outside of hollow nanospheres during the sodiation/desodiation processes. Our work offers a promising design to enable high-power-density electrodes for the various battery systems.

Stretchable ionic conductors with multiple functions provide new opportunities for flexible electronics, soft robots, and wearable devices. However, the practical applications of the existing stret...

Exploiting high efficient non-noble metal catalysts with low-cost and good stability for oxygen reduction reaction (ORR) is vital for fuel cells and metal-air batteries. In this work, we successfully constructed a novel nanosheets-shaped NiCoO2 hierarchical structure supported on CMK-3 support (i.e., NiCoO2@CMK-3 composite) via a facile hydrothermal method. Electrochemical characterization results reveal that the as-prepared NiCoO2@CMK-3 composite exhibits remarkable ORR electrocatalytic activity with a positive peak potential of 0.81 V (vs. RHE), an onset potential of 0.90 V (vs. RHE), a high current density of 4.10 mA cm−2 at 0.4 V, and a nearly four-electron reduction pathway, which are comparable to the state-of-the-art Pt/C catalyst with the same mass. In addition, the NiCoO2@CMK-3 composite possesses excellent methanol-tolerance and electrochemical stability, which are better than Pt/C. The outstanding performance confirms the NiCoO2@CMK-3 composite as a promising efficient ORR catalyst in fuel cells and metal-air batteries.

Rechargeable alkali metal-ion batteries (AMIBs) are receiving significant attention owing to their high energy density and low weight. The performance of AMIBs is highly dependent on the electrode materials. It is, therefore, quite crucial to explore suitable electrode materials that can fulfil the future requirements of AMIBs. Herein, a hierarchical hybrid yolk-shell structure of carbon-coated iron selenide microcapsules (FeSe2 @C-3 MCs) is prepared via facile hydrothermal reaction, carbon-coating, HCl solution etching, and then selenization treatment. When used as the conversion-typed anode materials (CTAMs) for AMIBs, the yolk-shell FeSe2 @C-3 MCs show advantages. First, the interconnected external carbon shell improves the mechanical strength of electrodes and accelerates ionic migration and electron transmission. Second, the internal electroactive FeSe2 nanoparticles effectively decrease the extent of volume expansion and avoid pulverization when compared with micro-sized solid FeSe2 . Third, the yolk-shell structure provides sufficient inner void to ensure electrolyte infiltration and mobilize the surface and near-surface reactions of electroactive FeSe2 with alkali metal ions. Consequently, the designed yolk-shell FeSe2 @C-3 MCs demonstrate enhanced electrochemical performance in lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries with high specific capacities, long cyclic stability, and outstanding rate capability, presenting potential application as universal anodes for AMIBs.

Practical applications of lithium-sulfur batteries are simultaneously hindered by two serious problems occurring separately in both electrodes, namely, the shuttle effects of lithium polysulfides and the uncontrollable growth of lithium dendrites. Herein, to explore a facile integrated approach to tackle both problems as well as guarantee the efficient charge transfer, we used two-dimension hexagonal VS2 flakes as the building blocks to assemble nanotowers on the separators, forming a symmetrical double-side-modified polypropylene separator without blocking the membrane pores. Benefiting from the "sulfiphilic" and "lithiophilic" properties, high interfacial electronic conductivity, and the unique hexagonal tower-form nanostructure, the D-HVS@PP separator not only guarantees the effective suppression of the lithium polysulfide shuttle and the rapid ion/electron transfer but also realizes uniform and stable lithium nucleation and growth during cycling. Hence, just at the expense of an 11% increase in the separator weight (0.14 mg cm-2), the D-HVS@PP separator delivers an over 16 times higher initial areal capacity (8.3 mAh cm-2) than a conventional PP separator (0.5 mAh cm-2) under high sulfur-loading conditions (9.24 mg cm-2). Even when used under a low electrolyte/sulfur ratio of 4 mL g-1 and a practically relevant N/P ratio of 1.7, the D-HVS@PP separator still enabled stable cycling with a high cell-level gravimetric energy density. The potentials in broader applications (Li-S pouch battery and Li-LiFePO4 battery) and the promising commercial prospect (large-scale production and recyclability) of the developed separator are also demonstrated.

Highly stretchable and transparent ionic conducting materials have enabled new concepts of electronic devices denoted as iontronics, with a distinguishable working mechanism and performances from the conventional electronics. However, the existing ionic conducting materials can hardly bear the humidity and temperature change of our daily life, which has greatly hindered the development and real-world application of iontronics. Herein, we design an ion gel possessing unique traits of hydrophobicity, humidity insensitivity, wide working temperature range (exceeding 100°C, and the range covered our daily life temperature), high conductivity (10 -3 ~10 -5 S/cm), extensive stretchability, and high transparency, which is among the best-performing ionic conductors ever developed for flexible iontronics. Several ion gel-based iontronics have been demonstrated, including large-deformation sensors, electroluminescent devices, and ionic cables, which can serve for a long time under harsh conditions. The designed material opens new potential for the real-world application progress of iontronics.

Exploring highly efficient non-Pt oxygen reduction reaction (ORR) electrocatalysts is an inevitable trend in the progress of various sustainable energy storage and conversion technologies. Herein, we prepare three kinds of hierarchical porous carbons, derived from hypercrosslinked polyaniline (HCP-An), polypyrrole (HCP-Py) and polymethylbenzene (HCP-MB) through a facile Friedel-Crafts reaction, among which NPC-An-900 exhibits outstanding ORR catalytic performance combining high surface area, good conductivity and high nitrogen-doped content. The hypercrosslinked polyaniline ensures micro-/mesoporous skeleton and prevents collapse during the pyrolysis process for NPC-An-900 with a high surface area of 2938.31 m2 g−1 and hierarchical micro-/mesoporous structure (1–8 nm). High nitrogen-doping content of NCP-An-900 is up to 7.02 at.% with pyridinic N as the main nitrogen doped type of 48.5% of the total nitrogen content. NPC-An-900 manifests an onset potential of 0.96 V (vs. RHE) with a high limiting current density of −5.31 mA cm−2 (superior to the commercial Pt/C of −5.20 mA cm−2) and excellent stability with current retention of 96.2% over 7.5 h. Furthermore, the extraordinary tolerance against methanol corrosion would also indicate its potential practical applications. This simple and universal synthesis strategy can be widely applied in the preparation of other porous heteroatom-doped carbons derived functional polymers towards energy storage and conversion.

Hybrid materials with delicate composition and morphology usually promote advanced functions. We report a simple synthesis approach to coaxially grow MoS2 nanosheets on carbon nanotubes (CNTs), which were precoated with polydopamine (PDA), with the ability to readily control phase and morphology. It is found that the thin PDA layer on CNTs surface with abundant catechol base and chinone base can effectively attract both Mo4+ and S2– for subsequently in situ forming MoS2 shell and sheet-like morphology, and therefore, it is essential for the successful deposition of MoS2. The as-prepared MoS2 nanosheets/CNTs (MoS2@CNT) composite with a unique hierarchical hybrid nanostructure with large active surface and enhanced structural robustness has greatly promoted the charge-transfer process and enhanced the electrochemical properties when used as the electrode materials for lithium-ion batteries and sodium-ion batteries. As the anode materials for LIBs, the MoS2@CNTs electrode exhibited extremely stable cycling p...

Graphene supported transition metal oxides (TMOs) nanocomposites have been recognized as an advisable strategy to develop the advanced electrodes for lithium-ion batteries (LIB) recently, yet the long-term cyclic stability could not be well maintained mainly due to the severe structural collapse and continuous exfoliation of active TMOs from graphene support. Herein, we successfully designed a novel sandwich-type hybrid nanostructure of reduced graphene oxide (rGO) enwrapped MnO nanooctahedra like a blanket (MnO@rGO NO) via a facile solution reflux and a post-annealing. The XRD patterns and FESEM images confirm that octahedral Mn3O4 precursor embedded among GO interlayers could be easily reduced into conformal MnO nanocrystal whilst the full reduction of GO into rGO during the subsequent calcination at 700 °C in N2. When used as a promising anode for LIBs, the sandwiched MnO@rGO NO manifests excellent lithium storage capability with high reversible discharge capacity, long-term cyclic stability and superb rate performance, mainly benefiting from the robust structure and good conductivity enhanced by rGO matrix. Even undergoing 600 cycles at the current densities of 400 and 800 mA g−1, the hybrid sandwiched MnO@rGO NO anodes could still deliver stable discharge capacities of 838 and 687 mAh g−1, respectively.

Hierarchical hybrid nanostructure of mesoporous ZnFe2O4 nanoparticles anchored on reduced graphene oxide (ZnFe2O4 NPs/rGO) has been successfully developed in this research via a fast low-temperature refluxing method and a subsequent-annealing treatment in N2. The unique mesoporous network structures of ZnFe2O4 NPs supported by flexible rGO sheets offer sufficient electrode-electrolyte contact, shorten Li+ ions diffusion distance, and thus greatly facilitate the electrochemical reactions via accommodating the volume change efficiently during cycling. Meanwhile, the conductive rGO matrix in the hybrid composite also ensures rapid electron transport to avoid the serve pulverization. Just based on such beneficial synergistic effect, the well-designed hierarchical hybrid ZnFe2O4 NPs/rGO composites present excellent lithium storage performance with high reversible discharge capacity, long-term cycle stability and superb high-rate capability when used as an anode for LIBs. A stable discharge capacity of as high as about 1106.7 mAh g−1 is well maintained even after 400 cycles at the current density of 200 mA g−1. We think this facile strategy could be further extended to the fabrication of other graphene-based electrodes for advanced energy applications.

The Ge-based compounds show great potential as replacements for traditional graphite anode in lithium-ion batteries (LIBs). However, large volume changes and low conductivity of such materials result in a poor electrochemical cycling and rate performance. Herein, we fabricate a self-supported and three-dimensional (3D) sponge-like structure of interlinked Zn2GeO4 ultrathin nanosheets anchored vertically on a nickel foam (ZGO NSs@NF) via a simple hydrothermal process assisted by cetyltrimethyl ammonium bromide (CTAB). Such robust self-supported hybrid structures greatly improve the structural tolerance of the active materials and accommodate the volume variation that occurs during repeated electrochemical cycling. As expected, the self-supported ZGO NSs@NF composites demonstrate an excellent lithium storage with a high discharge capacity, a long cycling life, and a good rate capability when used as binder-free anodes for LIBs. A high reversible discharge capacity of 794 mA h g-1 is maintained after 500 cycles at 200 mA g-1, corresponding to 81% capacity retention of the second cycle. Further evaluation at a higher current density (2 A g-1) also delivers a reversible discharge capacity (537 mA h g-1) for this binder-free anode. This novel 3D structure of the self-supported ultrathin nanosheets on a conductive substrate, with its volume buffer effect and good interfacial contacts, can stimulate the progress of other energy-efficient technologies.

Transition metal vanadates have gained significant attention as high performance anode materials for lithium ion batteries (LIBs). Herein, we successfully fabricated a novel hierarchical hybrid nanostructure of ordered mesoporous carbon (CMK-3) supported Ni3V2O8 composites (Ni3V2O8@CMK-3) through a facile hydrothermal method and a post-calcination process for the first time. Within such a hierarchical hybrid structure, short intercrossed Ni3V2O8 nanorods are firmly anchored onto the external surface of CMK-3 and ultrafine Ni3V2O8 nanoparticles are embedded in the internal channels of CMK-3. Benefitting from their robust porous structure and excellent conductive characteristic, the as-prepared hierarchical hybrid Ni3V2O8@CMK-3 composites exhibit long-term cycle stability with a high reversible capacity of 945.9 mA h g−1 after 200 cycles at a current density of 500 mA g−1 and superior high-rate capability (161.5 mA h g−1 when cycled at 20 A g−1) when used as a promising anode for LIBs.

Carbonaceous hybrid nanocomposites with a porous flaky structure hold great promise as high-performance electrodes for lithium-ion batteries (LIBs); yet large-scale synthesis is still a challenge. In this work, we successfully develop a novel carbon hybrid structure of carbon-coated ZnFe2O4 nanoflakes (ZnFe2O4@C NFs) through a fast ethylene glycol (EG)-mediated metal alkoxide method, refluxing at 200 °C in EG and a post-calcination at 500 °C in a N2 atmosphere. The organic components in the pre-synthesized ZnFe-alkoxide precursor (ZnFe2(OCH2CH2O)4) can be transferred into an amorphous carbon layer easily surrounding the crystalline ZnFe2O4 subunits during the annealing process. The flaky morphologies of the as-prepared ZnFe2O4@C hybrids are highly dependent on the refluxing temperature. Upon increasing the refluxing temperature from 140 °C to 200 °C, the sphere-like morphology of the ZnFe2O4@C composites gradually evolves into microflowers and separate nanoflakes. When used as an anode for LIBs, the hybrid ZnFe2O4@C NFs present excellent electrochemical performance with high discharge capacity, long-term cyclic stability and superior high-rate capability. Even after 1000 cycles at 0.5 A g−1, the hybrid ZnFe2O4@C NFs still deliver a stable reversible discharge capacity of 778.6 mA h g−1.

Nickel hydroxide (Ni(OH)2) has been regarded as a potential next-generation electrode material for supercapacitor owing to its attractive high theoretical capacitance. However, practical application of Ni(OH)2 is hindered by its lower cycling life. To overcome the inherent defects, herein we demonstrate a unique interconnected honeycomb structure of g-C3N4 and Ni(OH)2 synthesized by an environmentally friendly one-step method. In this work, g-C3N4 has excellent chemical stability and supports a perpendicular charge-transporting direction in charge–discharge process, facilitating electron transportation along that direction. The as-prepared composite exhibits higher specific capacities (1768.7 F g–1 at 7 A g–1 and 2667 F g–1 at 3 mV s–1, respectively) compared to Ni(OH)2 aggregations (968.9 F g–1 at 7 A g–1) and g-C3N4 (416.5 F g–1 at 7 A g–1), as well as better cycling performance (∼84% retentions after 4000 cycles). As asymmetric supercapacitor, g-C3N4@Ni(OH)2//graphene exhibits high capacitance (51 F g–...

Hybrid carbon-coated transition metal oxides (TMOs@C) offer enhanced lithium storage capabilities, but the facile formation of TMOs@C nanocomposites remains a great challenge. Herein, we report a novel hierarchical hybrid nanostructure of carbon-coated CoFe2O4 twin elliptical frustums (CoFe2O4@C TEFs) via a quick one-pot refluxing reaction in ethylene glycol (EG) followed by an annealing treatment. When evaluated as an anode in lithium-ion batteries (LIBs), the resultant CoFe2O4@C TEF hybrids demonstrate good electrochemical performance with high reversible specific capacity, excellent rate capability and super-long life cycle. After 600 cycles at a current density of 500 mA g−1, the resultant TEFs still deliver a stable reversible discharge capacity of 875 mA h g−1. This work demonstrates the extensive potential of such simple synthetic methods towards various carbon coated transition metal oxide composites for energy conversion and storage devices.

In this work, we developed a novel hierarchical hybrid nanostructure of reduced graphene oxide (rGO) supported cobalt-doped ZnO nanoparticles (Co-doped ZnO NPs@rGO) via a simple solution-refluxing strategy. The ultrafine CoZn-glycolate nanoparticles precursor was obtained from the alkoxide reaction among ethylene glycol and Co 2+ /Zn 2+ ions absorbed onto GO support. The post-annealing process makes the precursor easily transferred into crystalline Co-doped ZnO NPs@rGO with well-retained morphology and the oxidation state of Co element to be Co 2+ in the final hybrid. When evaluated as an oxygen reduction reaction (ORR) electrocatalyst in an O 2 -saturated 0.1 M KOH solution, the Co-doped ZnO NPs@rGO hybrid with the optimal Co-doping concentration of 0.38 ( i.e. , Co 0.38 Zn 0.62 O NPs@rGO) exhibits highly enhanced ORR electrocatalytic activity compared to the ZnO@rGO composite with an ORR peak potential of 0.74 V ( vs . RHE), an onset potential of 0.90 V, a current density of 3.94 mA cm −2 (at 0.4 V (vs. RHE)) and a nearly four-electron catalytic pathway. The good electrochemical stability and excellent methanol-tolerance capability of the resultant Co 0.38 Zn 0.62 O NPs@rGO hybrid, superior to those of the commercial Pt/C catalyst, further demonstrate its great potential as an efficient ORR electrocatalyst. This work proposes the feasibility of the semiconducting ZnO nanomaterials as novel ORR electrocatalysts via doping active oxygen catalytic element, such as Co 2+ , for the first time.

Sodium ion battery is abundant in resources and costs low, making it very competitive in the large-scale energy storage devices. The anatase TiO

As a member of the ternary metal oxide family, nickel cobaltite is considered as a promising electrode material. This is due to its high theoretical capacity, low diffusional resistance to protons, ease of electrolyte penetration, superior ionic/electronic conductivity and higher electrochemical activity compared to single metallic oxides such as NiO or Co3O4. However, NiCo2O4's relatively low electrical conductivity and its tendency to pulverize due to the volume changes experienced during the charge–discharge process remain a pressing issue to be solved. Here we demonstrate a simple co-precipitation and calcination routine to graft ultrathin NiCo2O4 nanosheets onto highly-ordered mesoporous carbon CMK-3 to form a new mesoporous-nanosheet structure which can accommodate stresses induced by volume changes and provide favourable conducting paths. The material exhibits a high specific surface area and excellent electrochemical performance, which can be ascribed to the ultrathin NiCo2O4 nanosheets and the interconnected conductive network of the mesoporous matrix. The nanosheets and the inner channels of CMK-3 are more beneficial to the diffusion of Li+ while the interconnected conductive network favours fast electron conduction.

Hierarchical hybrid nanostructures based on flexible graphene sheets and ternary transition metal oxides have attracted special attention as high-performance electrode materials for next-generation lithium-ion batteries (LIBs) yet their practical application is often beset with challenges. In this work, we report a hierarchical hybrid nanocomposite of reduced graphene oxide supported mesoporous Co3V2O8 nanoparticles (rGO@Co3V2O8 NPs) through a simple hydrothermal synthesis and post-calcination. This unique hybrid architecture when used as an anode in LIBs would effectively facilitate charge transfer, maintain structural integrity and accommodate the volume variation of the electrode materials during the repeated charge/discharge processes. As a result, the hybrid rGO@Co3V2O8 NPs manifest a very stable high reversible capacity of 1050 mA h g−1 over 200 cycles at a current density of 50 mA g−1 and excellent rate capability. Importantly, even when cycled at a higher current density of 200 mA g−1, a stable reversible capacity of 899 mA h g−1 and a remarkable cycling stability could also be achieved after 600 cycles. These results indicate the potential suitability of such mesoporous nanoparticles on graphene nanostructures for high-rate and long cycle life anode materials.

Carbonaceous hybrid nanocomposites with a porous flaky structure hold great promise as high-performance electrodes for lithium-ion batteries (LIBs); yet large-scale synthesis is still a challenge. In this work, we successfully develop a novel carbon hybrid structure of carbon-coated ZnFe

In this paper, a nanosheet-on-sheet architecture constructed from hierarchical, ultrathin, standing NiO nanosheets and rGO (denoted as NiO NSs@rGO) is successfully synthesized through a facile route. When evaluated as an anode electrode material for lithium ion batteries, the results show that the NiO NSs@rGO composite exhibits outstanding lithium storage performances with high specific capacity and excellent rate performance. The smart nanosheet-on-sheet architecture and its favorable synergistic effect between NiO and rGO make a contribution to the excellent electrochemical performance.

Hybrid nanosheet structures based on carbon coated metal oxides still attract promising interest as high-performance electrode materials for next-generation lithium-ion batteries (LIBs). In this study, we develop a simple one-pot solution method to synthesize large-scale flat Fe3O4 nanosheet hybrid structures coated with an amorphous carbon overlayer (denoted as Fe3O4@C NSs) followed by a thermal annealing treatment. It is found that the refluxing temperature plays an important role in adjusting the morphology of the Fe3O4@C hybrid. Increasing the temperature from 140 °C to 200 °C will lead to flower-like hybrid structures constructed by Fe3O4 nanoflakes gradually growing, rupturing, and finally evolving into flat and completely separate nanoflakes with large size at 200 °C. When evaluated as an anode material for LIBs, the hybrid Fe3O4@C NSs demonstrate a high reversible capacity of 1232 mA h g−1 over 120 cycles at a current density of 200 mA g−1, and remarkable rate capability.

Considering the importance of electromagnetic shielding fillers in the advanced electromagnetic shielding material and the shortcomings of the current fillers in electrical and magnetic conductivity properties, a facile two-step electroless plating process, including coating nickel layer onto nano-SiO2 followed by coating another Ag layer onto SiO2/Ni obtained, was developed to fabricate electromagnetic shielding fillers in this study. The effects of SiO2 loadings on the thickness, density, magnetic permeability and electric conductivity of as obtained SiO2/Ni/Ag fillers have been investigated completely. The results indicated the thickness of Ni and Ag layer could be finely tuned by changing the content of SiO2 and SiO2/Ni during electroless plating processes. The optimised SiO2/Ni/Ag nanocomposites demonstrate high magnetic permeability and excellent electrical conductivity with 1·60×10−5 H m and 1·82×10−5 Ω m respectively. This method provides a facile and low cost strategy to fabricate nano-fi...

Ultrathin scale-like nickel cobaltite (NiCo2O4) nanosheets supported on nitrogen-doped reduced graphene oxide (N-rGO) are successfully synthesized through a facile co-precipitation of Ni2+ and Co2+ in the presence of sodium citrate and hexamethylenetetramine and subsequent calcination treatment. The composition and morphology of NiCo2O4 nanosheets@nitrogen-doped reduced graphene oxide (denoted as NiCo2O4 NSs@N-rGO) were characterized by Scanning electron microscope, Transmission electron microscope, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller and thermogravimetric analysis. The thickness of NiCo2O4 nanosheets anchored on the reduced graphene oxide is around 4 nm. The capacitance of NiCo2O4 NSs@N-rGO is evaluated by cyclic voltammogram and galvanostatic charge/discharge with the result that the NiCo2O4 NSs@N-rGO could deliver a specific capacitance of 1540 F g−1 after 1000 cycles at 10 A g−1.

The Ge-based compounds show great potential as replacements for traditional graphite anode in lithium-ion batteries (LIBs). However, large volume changes and low conductivity of such materials result in a poor electrochemical cycling and rate performance. Herein, we fabricate a self-supported and three-dimensional (3D) sponge-like structure of interlinked Zn

Sodium ion battery is abundant in resources and costs low, making it very competitive in the large-scale energy storage devices. The anatase TiO2 electrode material with insertion/extraction mechanism shows stable cycling performance, which is more in line with the technical requirements of large-scale energy storage batteries. To improve the electrical conductivity and stability of the TiO2 electrode materials, we have synthesized anatase TiO2 and CMK-3 composite. TiO2 nanoparticles were deposited on the surface of CMK-3 by hydrothermal reaction, and the anode material of the SIBs with 3D network structure was prepared. With the CMK-3, the structure stability, conductivity and reaction kinetics of TiO2@CMK-3 composite is improved. The electrochemical behavior is dominated by pseudocapacitance, which gives the material excellent high-rate performance. It delivers a reversible specific capacity of 186.3 mA h g-1 after 100 cycles at the current density of 50 mA g-1, 124.5 mA h g-1 after 500 long-term cycles, meanwhile it shows an outstanding rate performance, a reversible specific capacity of 105.9 mA h g-1 at 1600 mA g-1, 177.3 mA h g-1 when the current density drops to 50 mA g-1.

Mesoporous SnO2 nanotubes are prepared by templating against carbon fibers through a facile solution approach followed by calcination at 800 °C for 2 h. The nanotubes are characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and nitrogen adsorption. The electrochemical performances as the anodes of lithium-ions batteries are studied by the cyclic voltammogram (CV) and galvanostatic discharge–charge voltage tests. Because of its unique structure (the mesoporous wall, internal void and open ends), the as-obtained mesoporous SnO2 nanotubes demonstrate a reversible capacity of 585 mA h g−1 up to 50 cycles at a high current density of 400 mA g−1.

For potential application in high energy storage capacitors with high energy density and low energy loss, three sets of poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] grafted with poly(methacrylic ester)s, including poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and poly(butyl methacrylate) (PBMA) copolymers, are designed and investigated carefully. Due to their intermediate polarity, relatively high glass transition temperature, and excellent compatibility with PVDF chains, the poly(methacrylic ester) segments introduced could not only dramatically weaken the coupling interactions of oriented polar crystals, but could also accelerate the reversal switching of polar crystal domains along the applied electric field, which leads to well hindered remnant polarization. As a result, the displacement–electric field (D–E) hysteresis behaviors of the graft copolymers could be tuned from typical ferroelectric to either antiferroelectric or linear shape under high electric field. Meanwhile, significantly reduced energy loss and effectively improved energy discharging efficiency were obtained. Compared with PMMA and PBMA, PEMA with intermediate polarity and grafting length exhibits more suitable confinement of the F–P transition of P(VDF-TrFE-CTFE), and thus more desirable energy storage properties are observed in the resultant copolymers. These findings may help to deeply understand the ferroelectric nature of PVDF based fluoropolymers and design new energy storage capacitor materials with high discharged energy density and low energy loss.

To improve the tensile strength, the bond strength, and the ablation resistant properties as well as the elongation at break of the short aramid fibers reinforced EPDM-based thermal insulation composites, two kinds of boron-containing phenolic resin, thermoplastic (TPBPR) and thermosetting (TSBPR), were added into the composites with a series of weight ratio of TPBPR and TSBPR, such as 0 : 20, 5 : 15, 10 : 10, 15 : 5, and 20 : 0. The effects of TPBPR and TSBPR weight ratio on the mechanical, bonding, and ablative properties of the composites were investigated systematically, respectively. The results showed that the crosslink density, the tensile strength, the bond strength, and the ablation resistant abilities of the composites decrease continuously with the increasing weight ratio, which confirms that the mechanical reinforcement and the ablation resistant abilities of TSBPR are higher than that of TPBPR. However, the elongation increases sharply with TPBPR and TSBPR weight ratio increasing. Therefore, the optimal weight ratio of TPBPR and TSBPR should be 10 : 10 to obtain the very thermal insulation composites with the excellent comprehensive properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010