Hybrid capacitors exhibit promise to bridge the gap between rechargeable high‐energy density batteries and high‐power density supercapacitors. This separation is due to sluggish ion/electron ...diffusion and inferior structural stability of battery‐type materials. Here, a topochemistry‐driven method for constructing expanded 2D rhenium selenide intercalated by nitrogen‐doped carbon hybrid (E‐ReSe2@INC) with a strong‐coupled interface and weak van der Waals forces, is proposed. X‐ray absorption spectroscopy analysis dynamically tracks the transformation from ReO into ReC bonds. The bridging bonds act as electron transport channels to enable improved conductivity and accelerated reaction kinetics. The expanded interlayer‐spacing of ReSe2 layer by INC facilitates ion diffusion and ensures structural stability. As expected, the E‐ReSe2@INC achieves an improved rate capability (252.5 mAh g−1 at 20 A g−1) and long‐term cyclability (89.6% over 3500 cycles). Moreover, theoretical simulations reveal the favorable Na+ storage kinetics can be ascribed to its low bonding energy of −0.06 eV and diffusion barrier of 0.08 eV for sodium ions. Additionally, it is demonstrated that 3D printed sodium‐ion hybrid capacitors deliver high energies/power densities of 81.4 Wh kg−1/0.32 mWh cm−2 and 9992.1 W kg−1/38.76 mW cm−2, as well as applicability in a wide temperature range.
The expanded rhenium selenide intercalated by nitrogen‐doped carbon hybrid with a strong‐coupled interface and weak van der Waals forces is prepared by topochemistry driven synthesis. The structural evolution is dynamically tracked from ReO into ReC bonds. The bridging bonds can act as electron transport “bridge” and supporting “pillar” between ReSe2 interlayer and INC, enabling improved electrical conductivity and ion diffusion coefficient.
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•The difference and necessity of each metal selenide are emphasized.•The methods proposed to address the volume changes of MSex are summarized.•The debate over the reaction mechanism ...of some of metal selenides is discussed.•The performance of metal selenides in the full-cell system is summed up.•The future research direction of metal selenides in SIBs is put forward.
In consideration of the abundance of sodium resources, sodium ion batteries (SIBs) have been revisited recently and are considered as a substitution for lithium ion batteries (LIBs). Among all the proposed anodes for SIBs, metal selenides labeled as high theoretical capacity materials have aroused the interest of battery researchers. However, as conversion/alloying based electrode materials, metal selenides suffer from a severe volume change during cycling, thus leading to kinetic problems and poor electrochemical stability, which restrain their further application in SIBs. Therefore, modification strategies such as coupling with carbonaceous material, designing unique structure, selecting an upper cut-off voltage, optimizing the composition of electrolyte, controlling the composition of the material etc. have been adopted to alleviate the volume change issue of metal selenides electrodes. In this article, the research progresses on the metal selenides as electrodes for SIBs are comprehensively reviewed and the difference and necessity of each metal selenide from the perspectives of structure and conductivity are emphasized. The summarization of metal selenides contains the synthesis methods, modification methods for performance improvement, corresponding reaction mechanism and performance in full-cell system. Finally, a conclusion with the challenges and outlook of metal selenides in the field of SIBs is also presented.
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•(Ni,Co)Se2/CoSe2/NF heterostructure electrocatalyst was desinged for water splliting.•The (Ni,Co)Se2/CoSe2/NF exhibied superior bifunctional OER/HER catalytic performances.•The ...constructed overall water-splitting cell achieves 10 mA cm−2 at 1.56 V.•The component synergy is responsible for the high electrocatalytic activity.
The green and pollution-free hydrogen produced by electrochemical water splitting as a clean energy carrier can effectively alleviate the energy crisis. Herein, we investigated and fabricated a unique heterostructure arrays of (Ni,Co)Se2 nanowires integrated with the metal–organic frameworks-derived (MOFs) CoSe2 dodecahedra on nickel foam (NF) as an effective binder-free electrode for water splitting. The as-synthesized (Ni,Co)Se2/CoSe2/NF electrocatalyst exhibits excellent electrochemical performance in alkaline solutions with HER and OER overpotentials as low as 65 mV and 255 mV, respectively, at a current density of 10 mA cm−2 as well as high stability. The alkaline electrolyzer for overall water splitting using (Ni,Co)Se2/CoSe2/NF as electrocatalyst requires only cell voltage of 1.56 V to drive a current density of 10 mA cm−2 and maintained without significant decay over 50 h. The unique heterostructure with abundant active sites and strong synergistic effect between (Ni,Co)Se2 nanowires and CoSe2 could modulate the electronic structure and enhance the charge transfer, thus contributing to high electrocatalytic activity. This study provides a suitable method and reference for optimizing the structure of bifunctional transition metal-based selenides to improve electrocatalytic water splitting performance.
This review investigates hydrothermal synthesis of metal selenides and diselenides. Briefly, structures, applications and formation mechanisms are studied. The strategies for developing metal ...selenides, including NiSe, NiSe2, Ni3Se2, CdSe, FeSe2, MnSe2, CoSe, CuSe, Cu1.8Se, CuSe2, Cu3Se2 and ZnSe are discussed. More of 50 hydrothermal methods used for the synthesis of metal selenides are discussed. As well as the investigation of the photocatalytic activities of these metal selenides are followed by different synthesis methods and strategies employed for the synthesis of them.
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•A review on hydrothermal synthesis and photocatalytic applications of MSes is investigated.•Mechanism of formation and magnetic properties of MSes are investigated.•More of 50 of the hydrothermal methods used for the synthesis of MSes are discussed.•Photocatalytic degradation of different dyes in the presence MSes is studied.•Effects of different parameters affecting on photocatalytic properties of MSes are investigated.
Exploring high‐rate electrode materials with excellent kinetic properties is imperative for advanced sodium‐storage systems. Herein, novel cubic‐like XFe (X = Co, Ni, Mn) Prussian blue analogs ...(PBAs), as cathodes materials, are obtained through as‐tuned ionic bonding, delivering improved crystallinity and homogeneous particles size. As expected, Ni‐Fe PBAs show a capacity of 81 mAh g−1 at 1.0 A g−1, mainly resulting from their physical–chemical stability, fast kinetics, and “zero‐strain” insertion characteristics. Considering that the combination of elements incorporated with carbon may increase the rate of ion transfer and improve the lifetime of cycling stability, they are expected to derive binary metal‐selenide/nitrogen‐doped carbon as anodes. Among them, binary Ni0.67Fe0.33Se2 coming from Ni‐Fe PBAs shows obvious core–shell structure in a dual‐carbon matrix, leading to enhanced electron interactions, electrochemical activity, and “metal‐like” conductivity, which could retain an ultralong‐term stability of 375 mAh g−1 after 10 000 loops even at 10.0 A g−1. The corresponding full‐cell Ni‐Fe PBAs versus Ni0.67Fe0.33Se2 deliver a remarkable Na‐storage capacity of 302.2 mAh g−1 at 1.0 A g−1. The rational strategy is anticipated to offer more possibilities for designing advanced electrode materials used in high‐performance sodium‐ion batteries.
Cubic‐like XFe (X = Co, Ni, Mn) Prussian blue analogs (PBAs) are designed through as‐tuned ionic bonding of XFe. Ni‐Fe PBAs as cathode show “zero‐strain” insertion traits with physical–chemical stability, and their derived binary metal‐selenide as anode displays strong metal‐like conductivity. Their matched sodium full‐cell systems deliver reasonably high and fast specific capacity.
The high-entropy selenides derived from Prussian blue analogues were selenated by the vapor infiltration method, resulting in the formation of a core–shell structured high-entropy selenides (HESe-6). ...As a result, the HESe-6 anode for SIBs can achieve excellent cyclability (107 % retention over 1000 loops at 1 A g−1), and remarkable rate capability (606.8 mAh g−1 at 5 A g−1).
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Transition metal selenides (TMS) have received much attention as anode materials for sodium-ion batteries (SIBs) because of their high theoretical capacity and excellent redox reversibility. However, their further development is constrained by the dissolution of transition metal ions and substantial volume changes experienced during cycling. Herein, the high-entropy Prussian blue analogues were selenized by the vapor infiltration method, resulting in the formation of a core–shell structured high-entropy selenides (HESe-6). The core–shell structure with voids and abundant selenium vacancies on the surface effectively mitigates bulk expansion and enhances electronic conductivity. Furthermore, the high-entropy property endows an ultra-stable crystal structure and inhibits the dissolution of metal ions. The ex-situ EIS and in-situ XRD results show that HESe-6 is able to be reversibly transformed into highly conductive ultrafine metal particles upon Na+ embedding, providing more Na+ reactive active sites. In addition, despite the incorporation of up to seven different elements, it exhibits minimal phase transitions during discharge/charge cycles, effectively mitigating stress accumulation. HESe-6 could retain an ultralong-term stability of 765.83 mAh g−1 after 1000 loops even at 1 A g−1. Furthermore, when coupled with the Na3V2(PO4)2O2F cathode, it maintains a satisfactory charge energy density of 303 Wh kg−1 after 300 cycles, which shows promising application prospect in the future.
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•Carbon-encapsulated MnSe-FeSe nanowires have been fabricated.•Heterostructure accelerates the electron transfer and ion diffusion.•MnSe-FeSe@C exhibits excellent rate capability and ...prolonged cycling durability.
The natural abundance of sodium has fostered the development of sodium-ion batteries for large-scale energy storage. However, the low capacity of the anodes hinders their future application. Herein, carbon-encapsulated MnSe-FeSe nanorods (MnSe-FeSe@C) have been fabricated by the in-situ transformation from polydopamine-coated MnO(OH)-Fe2O3. The heterostructure constructed by MnSe and FeSe nanocrystals induces the formation of built-in electric fields, accelerating electron transfer and ion diffusion, thereby improving reaction kinetics. In addition, carbon enclosure can buffer the volumetric stress and enhance the electrical conductivity. These aspects cooperatively endow the anode with superior cycling stability and distinguished rate performance. Specifically, the discharge capacity of MnSe-FeSe@C reaches 414.3 mA h g−1 at 0.1 A g−1 and 388.8 mA h g−1 even at a high current density of 5.0 A g−1. In addition, it still retains a high reversible capacity of 449.2 mA h g−1 after 700 long cycles at 1.0 A g−1. Further, the ab initio calculation has been employed to authenticate the existence of the built-in electric field by Bader charge, indicating that 0.24 electrons in MnSe were transferred to FeSe. The in-situ XRD has been used to evaluate the phase transition during the charging/discharging process, revealing the sodium ion storage mechanism. The construction of heterostructure material paves a new way to design performance-enhanced anode materials for sodium-ion batteries.
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Metal selenides are promising anode candidates for sodium ion batteries (SIBs) because of their high theoretical capacity, low cost, and environmental friendship. However, the low ...rate capability at high current density due to its inherent low electrical conductivity and poor cycle stability caused by inevitable volume variations during cycling frustrate its practical applications. Herein, we have developed a simple metallic-organic frameworks (MOFs)-derived selenide strategy to synthesize a series of heterogeneous bimetallic selenides encapsulated within graphene aerogels (GA) as anodes for SIBs. The bimetallic selenides/GA composites have unique structural characteristics that can shorten the migration path for Na+/electrons and accommodate the volume variations via additional void space during cycling. The built-in electric fields induced at the heterointerfaces can greatly reduce the activation energy for rapid charge transfer kinetics and promote the diffusion of Na+/electrons. GA is also beneficial for accommodating the volume variations during cycling and improving conductivity. As an advanced anode for SIBs, the MoSe2-Cu1.82Se@GA with a special porous octahedron can deliver the highest capacity of 444.8 mAh/g at a high rate of 1 A/g even after 1000 cycles among the bimetallic selenides/GA composites.
•The difference and necessity of each metal selenide are emphasized.•The correlations bewteen performance and structures of metal selenides are revealed.•The challenges and outlook of metal selenides ...in energy storage and conversion are also discussed.
Developing advanced energy devices with long-term operation characteristics has attracted much attention in energy storage and conversion. It proposes new demands for electrode and catalyst materials with structural controllability, electrochemical stability, and intrinsic conductivity. Fortunately, metal selenides can meet these requirements, which are the rising star of emerging candidates for energy devices nowadays. This article provides a comprehensive and critical review on the recent state-of-the-art progress of metal selenides for energy storage and conversion. The difference and necessity of each metal selenide are emphasized. The crystal and electronic structures and synthesis and modification methods of metal selenides are summarized to reveal their correlation with the performance of energy storage and conversion devices. The challenges and outlook of metal selenides in energy storage and conversion are also discussed. This review is expected to give us a deep understanding of the structure, methodology, and application of metal selenides in energy storage and conversion, which will certainly facilitate the research on this issue in the near future.
PPy-encapsulated Cu2Se nanosheetsin-situ grown on the Cu mesh (Cu2Se@PPy) acts as a high-performance anode for sodium-ion batteries, capable of delivering a high specific capacity of 293.0 mAh g−1 at ...1.0 A g−1, impressive rate capacity of 263.5 mAh g−1 under 10.0 A g−1 over 2000 cycles.
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•Cu2Se nanosheets were in-situ grown on Cu mesh at room temperature.•PPy coating layer enables robust structure stability and fast charge transport.•Cu2Se@PPy as a SIBs anode gives high specific capacity.•Cu2Se@PPy as a SIBs anode offers outstanding cycling durability.
Copper selenide (Cu2Se) features high theoretical capacity and quasi-2D characteristics built by repeating sextuple layers of Se-Cu-Cu-Cu-Cu-Se, making it a fascinating anode for sodium-ion batteries (SIBs). However, it experiences huge volume variation during repeated discharge–charge processes. Here, a productive approach to preserve the structure of Cu2Se anode via in-situ coating conductive polymer carbon is proposed. As a demonstration, Cu2Se nanosheets encapsulated by polypyrrole (PPy) were anchored on Cu mesh (Cu2Se@PPy) and regarded as an electrode material for SIBs. The PPy shell enjoys double functions that improves the electronic conductivity as well as alleviates the significant volume swelling of Cu2Se. As a result, Cu2Se@PPy gives a satisfactory electrochemical performance, including high specific capacity of 293.0 mAh g−1 at 1.0 A g−1, impressive rate capacity (263.5 mAh g−1 under 10.0 A g−1 over 2000 cycles). This work describes the uncomplicated approaches available for designing high stability metal selenides anodes for sodium storage.
