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With the in-depth research of sodium-ion batteries (SIBs), the development of novel sodium-ion anode material has become a top priority. In this work, tube cluster-shaped SbPS4 was synthesized by a high-temperature solid phase reaction. Then the typical short tubular ternary thiophosphate SbPS4 compounded with graphene oxide (SbPS4/GO) was successfully synthesized after ultrasonication and freeze-drying. SbPS4 shows a high theoretical specific capacity (1335 mAh/g) according to the conversion-alloying dual mechanisms. The unique short tube inserted in the spongy graphene structure of SbPS4/GO results in boosting the Na ions transport and alleviating the huge volume change in the charging and discharging processes, improving the sodium storage performance. Consequently, the tubular SbPS4 compounded with 10% GO provides an outstanding capacity of 359.58 mAh/g at 500 mA/g. The result indicates that SbPS4/GO anode has a promising application potential for SIBs.

Summary Oriented attachment (OA) growth has shown great significance in the development of crystal growth theory over the past decade, which is generally acknowledged as a physical process. Here, we report a different OA growth manner, which involves not only the physical nanoparticle attachment but also the chemical reaction between nanoparticles and ions. It is demonstrated that with the participation of NaHCO3 and NH4HCO3, micron-sized sheets of NaY(CO3)2·6H2O and (NH4)Y(CO3)2·H2O can be formed from Y2(CO3)3·2H2O nanoparticles through a chemical-reaction-directed OA. In contrast to the conventional OA process, this OA growth can produce single-crystalline substances whose crystallographic structures and chemical constituents are different (usually more complicated) from those of precursor nanoparticles. Such an OA mechanism shows applicability in a number of salts. Our findings not only extend the territory of the non-classical aggregation-based crystal growth mode but also provide a feasible approach for creating functional materials with complex architectures.

The constantly increasing demands on sustainable and high-performance energy storage devices generate tremendous research attentions on novel battery systems. Rechargeable magnesium battery (RMB), which possesses the advantages of low cost, natural abundance, has emerged as a considerable candidate. The fascinating features of high volumetric capacity, dendrites free and earth abundance also made it more fascinating. However, owing to the strong polarization of Mg ions, the existing electrodes and electrolyte cannot fully facilitate the Mg2+ ion insertion/extraction. In this regard, finding suitable electrode materials and electrolytes with high Mg insertion kinetics, excellent reversibility and costless are still the challenges that hinder the practical application of RMB. In this review, we mainly attempt to accumulate the recently advances in the development of electrodes, as well as development of advanced hybrid RMB systems. The review specifically aimed to provide new perspectives on the construction of novel electrode materials. Moreover, the challenges and perspective of RMBs are also discussed to highlight the limitations and the future direction. These may inspire more efforts on future work and accelerate the development process.

Rechargeable zinc-ion batteries (ZIBs) appear to be a promising candidate for large-scale energy storage system because of the abundance and inherent safety of the zinc negative electrode. Despite these benefits, huge polarization caused by the intercalation of multivalent charge carrier Zn2+ into the cathodic hosts remains a long-standing challenge impeding the development of high-performance ZIBs. Herein, we demonstrate the viability of the V2O5 nanorods constructed 3D porous architectures (3D-NRAs-V2O5) as cathode for ZIBs. Notably, the 3D-NRAs-V2O5 can be scaled up to kilo-gram production based on a simple sol-gel reaction followed by an annealing process. The synergic contributions from the 3D porous framework and layered structures of the 3D-NRAs-V2O5 lead a more facile Zn2+ ions (de)intercalation storage process. Consequently, it offers high reversible capacity of 336 mAh g−1 at a high current density of 50 mA g−1 and exhibits excellent long-term cyclic stability with a capacity retention of 85% over 5000 cycles at a high current density of 10 A g−1. Furthermore, the use of various ex-situ characterization techniques and first-principles calculations has successfully unravelled the Zn2+ ions storage mechanism of the 3D-NRAs-V2O5. Besides the excellent electrochemical performance of the 3D-NRAs-V2O5, it can also be easily scaled up based on the simple synthetic protocol, which shows great potential to be practically used for the next-generation large-scale energy storage applications.

In this manuscript, the graphene-encapsulated MnMoO4 hollow spheres (MnMoO4@G) synthesized by an effective strategy were reported. Benefiting from the intriguing hybrid architecture of hollow structure and conductive graphene network, the MnMoO4@G composite displays superior electrochemical performance with high specific capacity of 1142 mA h g−1, high reversible cycling stability of 921 mA h g−1 at a current density of 100 mA g-1 after 70 cycles, and stable rate performance (around 513 mA h g−1 at a current density of 4.0 A g−1). The remarkable battery performance can be attributed to the rational design of the architecture, which not only ensures the fast transport of electrons and lithium ions within the electrode material, but also effectively relax the stress induced by the insertion/extraction of lithium ions. This facile synthetic method can extend to other transition metal oxides with large volume excursions and poor electric conductivity and promotes the development of transition metal oxides as high-performance LIB anode material.

Transition metal selenides are widely explored as promising anodes for sodium-ion batteries (SIBs) because of their high theoretical capacity. However, rapid capacity decay caused by the structural collapse during cycling greatly hampers their applications in SIBs. Herein, we report a synergistic engineering of interface and structure to synthesize CoSe2–MoSe2 yolk-shell spheres. Such exquisite boundary architecture is beneficial to improving the electrochemical kinetics. Meanwhile, the yolk-shell structure further modulates the mechanical stress for stable performance. As expected, the CoSe2–MoSe2 yolk-shell spheres deliver a high capacity of 466 mAh g−1 after 1000 cycles at the ultrahigh rate of 10 A g−1. The sodium storage mechanism of the CoSe2–MoSe2 yolk-shell spheres is investigated by kinetic tests and first-principles calculations. Coupled with a Na3V2(PO4)2O2F cathode, the as-constructed full batteries show a remarkable energy density of 133 Wh kg−1, promoting the development of high-energy density energy storage devices.

Searching low cost and non-precious metal catalysts for high-performance oxygen reduction reaction is highly desired. Herein, Co nanoparticles embedded in nitrogen-doped carbon (Co/NâC) nanotubes with internal void space are successfully synthesized by space-confined pyrolysis, which effectively improve the cobalt loading content and restrict the encapsulated particles down to nanometer. Different from the typical conformal carbon encapsulation, the resulting Co/NâC nanotubes possess more cobalt nanoparticles embedded in the nanotubes, which can provide more coupling sites and active sites in the oxygen reduction reaction (ORR). Moreover, the one-dimensional and porous structure provides a high surface area and a fast electron transfer pathway for the ORR. And the Co/NâC electrode presents excellent electrocatalytic ORR activity in terms of low onset potential (30Â mV lower than that of Pt/C), small Tafel slop (45.5Â mVÂ decâ1) and good durability (88.5% retention after 10,000Â s). Keywords: Co nanoparticles, Nitrogen-doped carbon nanotubes, Oxygen reduction reaction

Developing stable, efficient and economical electrocatalytic materials is still challenging for hydrogen evolution reaction (HER). Hence, we develop a Pd/Ni bimetallic carbon electrocatalyst (Pd/Ni-NC) with outstanding electrocatalytic performance. The catalyst derived from Pd-doped Ni-MOF (Pd/Ni-MOF) has particles and needle-like carbon tubes on its surface and is similar in shape to setaria. Benefiting from the composition and the unique structure, Pd/Ni-NC shows excellent HER catalytic performance with 16 mV at 10 mA cm−2, superior to Pd or Ni single metal-carbon catalyst. Furthermore, it maintains stable catalytic activity under constant current for 25h. These results show the strategy that obtaining Pd and Ni bimetallic MOF by cation exchange and its corresponding bimetallic carbon material with setaria-shaped structure by calcination is powerful for high efficient HER performance.

Aqueous zinc‐ion batteries (AZIBs) have received significant research attention and widely investigated because of their high intrinsic safety and cost effectiveness. Manganese dioxide has been regarded as a promising cathode material for AZIBs, attributed to its friendliness, abundant resources, high theoretical capacity, and high working voltage. Herein, a unique one-dimensional–three-dimensional (1D–3D) hybrid network with interconnected δ-MnO2 nanowires was reported as a cathode material for AZIBs. A distinctive 3D nano network structure resulted in enhancement of electrolyte osmosis and significant increase in contact between electrode and electrolyte, and also provided more active sites and convenient rapid ion transport routes. Moreover, the fine nanowire structure and the optimum layer spacing resulted in easier insertion/deinsertion of ion in the active material. Taking advantage of this feature, the δ-MnO2 cathode provides high reversible capacity, fast rate capability and good longevity for cycling. Further kinetic experiments revealed that Zn/δ‐MnO2 system constitutes an electrochemical reaction regulated by the combination of ionic diffusion and pseudo-capacitance; and shows high energy efficiency during the charge/discharge states. This research may provide an advanced cathode material for AZIB development.

Exploring cost-effective and efficient electrocatalysts for simultaneous hydrogen production and environment purification is of great charm. Herein, a bifunctional electrocatalyst is designed by integrating cobalt nitride (CoN) and nickel hydroxide (Ni(OH)2) on nickel foam. The generated CoN/Ni(OH)2 heterostructures are comprised of the CoN (111) and Ni(OH)2 (001) with the 2.8% low lattice mismatch, in which the polar plane of CoN (111) is beneficial for the charge transfer between interfaces, guaranteeing the excellent properties toward both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). For alkaline HER, the optimal electrocatalyst delivers the superior activity with a small overpotential of 40 mV at 10 mA cm−2 and low Tafel slope of 48 mV dec−1. Furthermore, an excellent UOR performance is also achieved (1.39 V@50 mA cm−2, 64 mV dec−1). Based on the superior HER and UOR electrocatalytic activities, the assembled electrolytic cell by integrating two optimal NF/CNNH electrodes as the anode and cathode can drive the current density of 10 mA cm−2 with the small cell voltage of 1.43 V and possess good stability. Our work may provide a valuable way for designing bifunctional electrocatalysts for both efficient energy-saving hydrogen generation and urea-rich wastewater purification.

Aqueous rechargeable metal batteries (ARMBs) represent one type of energy storage technology with high theoretical energy densities, low cost and better safety. Their practical applications are hindered by the narrow voltage window of the aqueous electrolytes, limited efficiency in the intercalation/deintercalation of the metal ions (especially for the multivalent ions) and dissolution/structural variation of the electrodes in aqueous electrolytes. Effective strategies have been developed to address the above issues and significantly advanced performance and mechanistic understanding of the aqueous system. In this review, we highlight the representative strategies in achieving high-energy ARMBs, i.e., aqueous rechargeable Li/Na/K/Zn/Mg/Al ion batteries. Strategies in optimizing the composition/structure of conventional anodes and cathodes, progress of “water-in-salt” electrolyte, and novel ion storage mechanisms other than the intercalation chemistry will be discussed. It is expected that this review can provide a comprehensive overview of the status of the ARMBs and enlighten more research work that tackle the unsolved bottleneck issues. Ministry of Education (MOE) National Research Foundation (NRF) Accepted version The authors gratefully acknowledge the National Natural Science Foundation of China (Grant No. 51972067, 21606003, 51802044, 51801030, and 61801314), Guangdong Natural Science Funds for Distinguished Young Scholar (Grant No. 2019B151502039), the 111 project (D18023), Singapore MOE AcRF Tier 2 under Grant Nos. 2018-T2-1-010 and MOE2017-T2-2-069 and National Research Foundation of Singapore (NRF) Investigatorship, award Number NRF2016NRF-NRFI001-22.

In this paper, we report a synthetic route for cobalt sulfides nanoparticles embedded in porous carbon fibers (Co9S8@C) by carbonizing polydopamine (PDA)-coated metal coordination polymers (MCPs) and subsequent sulfidation process. This material serves as an anode for lithium-ion batteries, which exhibits high capacity and good rate capability. At a rate of 0.1C, a high reversible capacity of 1565 mA h g−1 is being obtained. In addition, the battery maintains a stable reversible capacities of 606 mA h g−1 for 300 cycles at 1C. The improvement of lithium-storage performance is mainly attributed to the smart design of carbon-wrapped mesoporous Co9S8 fibers, which not only prevents aggregation and volume change of the Co9S8 particles, but also enables good conductivity, and thus enhances electrochemical stability.

Chiral carbon-based nanomaterials possess many superior properties originated both from their nano-sized structure and their chirality. We presented a facile way to synthesize chiral mesoporous carbonaceous nanofibers (chiral MCNFs) through a supramolecular templating method, using a pair of chiral low-molecular-weight gelators as the templates, resorcinol, formaldehyde and tetraethyl orthosilicate as the precursors, respectively. Besides, the chiral MCNFs exhibited optical activity; the electrochemical measurements implied that they also showed good capacitance and lithium-ion storage performances.

Aqueous zinc-ion batteries (ZIBs) have been of excellent interest in the latest years due to their environmental benignity and easy preparation. One vital barrier to the production of high-performance ZIBs is the development of appropriate cathode materials. Polyaniline (PANI) is very promising, particularly due to its excellent conductivity and easy preparation, among varied cathode materials. However, deprotonation of PANI is a key problem greatly deteriorating capacity and cycling stability of PANI cathode. In this study, we discover that graphene oxide (GO) can fix the problem effectively as the wealthy functional GO oxygen groups can provide a local proton reservoir that increases PANI protonation. As a result, the GO composited PANI electrodes show significantly improved zinc-ion storage performance than pure carbon composited PANI cathodes. Specifically, the battery performances in terms of capacity (233 mA h g−1) and rate performance (100 mA h g−1 under 5 A g−1) are enhanced significantly after introducing GO into PANI cathode. Besides, flexible PANI-based ZIB devices can be easily fabricated owing to the excellent film-forming property of GO. This work offers new insight for improving PANI cathode materials by carbon chemistry.

Herein, we reported a facile route to fabricate carbon and Au treated TiO 2 mesoporous hollow spheres (MHTiO 2 @C–Au) as high performance anode materials for lithium ion batteries. The high porosity of the hollow spheres, together with the inner carbon supporting and superficial Au coating, enhanced the cycling stability and rate performance of the MHTiO 2 @C–Au electrode significantly. The MHTiO 2 @C–Au composite exhibits a high reversible specific capacity of 186.6 mA h g −1 after 200 cycles at the current density of 1.0C, superior rate performances of around 151.0 mA h g −1 at the current rate of 5.0C. The outstanding electrochemical property is attributed to the overall structural features of the MHTiO 2 @C–Au, which can not only shorten the diffusion path of lithium ions and electrons, but also improve the stability of the hollow structures during the lithium ion insertion and extraction process.

In this manuscript, we demonstrated a facile route for the controllable design of “Fluorine (F)-doped carbon” (C/F)-treated TiO 2 hollow spheres with mesoporous shells (MHTO-C/F). The fabrication of this distinct mesoporous hollow structures and the C/F coating could effectively improve the electrolyte permeability and architectural stability, as well as electrical conductivity and lithium ion mobility. As anticipated, MHTO-C/F has several remarkable electrochemical properties, such as a high specific reversible capacity of 252 mA h g −1 , outstanding cycling stability of more than 210 mA h g −1 after 100 cycles at 0.5 C, and good rate performance of around 123 mA h g −1 at 5 C (1 C = 168 mA g −1 ). These properties are highly beneficial for lithium storage.

Recently, aqueous zinc ion batteries have emerged as attracting alternatives to conventional lithium ion batteries with the merits of low cost and operation safety. However, the Zn host material with fast Zn kinetic and could sustain reversible Zn2+ insertion and extraction is still a big challenge. Here, a nanowire morphology (NH4)2V6O16·1.5H2O nanostructures fabricated via a facile microwave-assisted hydrothermal reaction are presented as a prospective zinc ion battery cathode. The trapped Zn(H2O)62+ ions in the initial discharge process not only help make the vanadium oxide layer stable but also provide enough interlayer distance for fast ion kinetics during the preceding intercalation/deintercalation process. Owing to the large interplane distance pillared by cations, crystal water molecular and the high diffusion coefficient of (NH4)2V6O16·1.5H2O cathode, it presents an excellent low temperature performance (120 mAh g−1 at a current density of 0.1 A g−1) and highly reversible cycling performance (75% after 10000 cycles at 8 A g−1). The outstanding performance, the easy fabrication along with the low-cost feature make (NH4)2V6O16·1.5H2O cathode reliable in aqueous zinc ion battery application.

The research on preparation and application of defect-free pristine graphene (PG) is a hot topic. However, large-scale non-destructive exfoliation of graphite into single-layered PG still remains a challenge. The common method of exfoliating graphite is based on the oxidation-exfoliation-reduction strategy. Nevertheless, there are many structural defects for the graphene produced by this approach due to the excessive oxidation and incomplete reduction processes, which significantly deteriorate the intrinsic properties of graphene. Therefore, researchers attempt to develop non-oxidative chemical/physical methods to directly exfoliate graphite into PG layers without damaging the sp2 carbon lattice, and utilize PG-based materials and structures for various applications. Herein, we review recent development on the direct exfoliation of graphite into PG via non-oxidative chemical methods. Firstly, we outline the various exfoliation systems based on different acting forces as well as liquid media, which are two key factors determining the ultimate exfoliation effect. Then the structural qualities of the PG sheets are discussed. Finally, we summarize in detail the diverse electrochemical energy applications of PG materials, and provide some perspectives for the future developments of PG materials towards commercialization.

Differences between adsorption properties for Hg(II) and Au(III) on polystyrene-supported bis-8-oxyquinoline-terminated open-chain crown ether (PS-DB) were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and the density functional theory (DFT) method. The comparison studies included kinetics, equilibriums and thermodynamics of the adsorption process. Pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data. The pseudo-second-order kinetic model provided a better correlation with the experimental data for Hg(II) in comparison with the pseudo-first-order model. While for Au(III), the conclusion was the reverse. Both the adsorption rate and adsorption amount at equilibrium for Hg(II) were greater than those for Au(III) ions, which was probably caused by the differences in form and volume between the two kinds of absorbed ions. Langmuir, Freundlich and Tempkin isotherm models were applied in the adsorption isotherm study. The results showed that the Langmuir and Tempkin isotherm models were more applicable in describing the processes. The thermodynamic parameters for the adsorption process such as free energy of adsorption (ΔG), enthalpy of adsorption (ΔH) and entropy of adsorption (ΔS) were calculated. The density functional theory (DFT) method was used to investigate the coordination geometries and the interactions between the metal ions with PS-DB. These results showed that the adsorption for Hg(II) was physisorption while that for Au(III) was chemisorption, which was also consistent with the data obtained from the Dubinin–Radushkevich (D–R) isotherm model and ΔH values.