Embedding ZnSe nanoparticles in a porous nitrogen-doped carbon framework for efficient sodium storage

Metal-organic framework derived bimetallic selenide embedded in nitrogen-doped carbon hierarchical nanosphere for highly reversible sodium-ion storage

Bimetallic selenides with various valence transitions and high theoretical capacities are extensively studied as anodes for sodium-ion-batteries (SIBs), but their huge volume changes and poor capacity retention limit their practicality. Herein, a facile and controllable strategy using a binary Ni-Co metal-organic framework (MOF) precursors followed by the selenization process, which produced a cobalt nickel selenide/N-doped carbon composite ((CoNi)Se₂/NC) that maintained the hierarchical nanospheres structure. Such a distinctive structure affords both Na⁺ and electron diffusion pathways in the electrochemical reactions as well as high electrical conductivity, thus leading to superior electrochemical performance when the designed composite is utilized as an anode in SIBs. The resulting nanospheres-like (CoNi)Se₂/NC hierarchical structure exhibits a high specific capacity of 526.8 mA h g^-1 at 0.2 A/g over 100 cycles, a stable cycle life with no obvious capacities loss at 1.0 and 3.0 A/g after 500 cycles, and exceptional rate capability of 322.9 mA h g^-1 at 10.0 A/g.

Research progress on ZnSe and ZnTe anodes for rechargeable batteries

Transition-metal chalcogenides (TMCs) with tunable direct bandgaps and interlayer spacing are attractive for energy-related applications. Semiconducting zinc chalcogenides, especially their selenides (ZnSe) and tellurides (ZnTe), with enhanced conductivity, high theoretical capacity, low operation voltage and abundance, have appeared on the horizon and receive increasing interest in terms of electrochemical energy storage and conversion. Despite the existing typical obstruction owing to the large volume change, relatively low electrical conductivity and sluggish ion diffusion kinetics into the bulk phase, several effective strategies such as compositing, doping, nanostructuring, and electrode/cell design have exhibited promising applications. We herein provide a timely and systematic overview of recent research and significant advances regarding ZnSe, ZnTe and their hybrids/composites, covering synthesis to electrode design and to applications, especially in advanced Li/Na/K-ion batteries, as well as the reaction mechanisms thereof. It is hoped that the overview will shed new light on the development of ZnSe and ZnTe for next-generation rechargeable batteries.

Synergistic Engineering of Se Vacancies and Heterointerfaces in Zinc-Cobalt Selenide Anode for Highly Efficient Na-Ion Batteries

The exploitation of effective strategies to accelerate the Na⁺ diffusion kinetics and improve the structural stability in the electrode is extremely important for the development of high efficientcy sodium-ion batteries. Herein, Se vacancies and heterostructure engineering are utilized to improve the Na⁺ -storage performance of transition metal selenides anode prepared through a facile two-in-one route. The experimental results coupled with theoretical calculations reveal that the successful construction of the Se vacancies and heterostructure interfaces can effectively lower the Na⁺ diffusion barrier, accelerate the charge transfer efficiency, improve Na⁺ adsorption ability, and provide an abundance of active sites. Consequently, the batteries based on the constructed ZnSe/CoSe₂ -CN anode manifest a high initial Coulombic efficiency (97.7%), remarkable specific capacities (547.1 mAh g^-1 at 0.5 A g^-1 ), superb rate capability (362.1 mAh g^-1 at 20 A g^-1 ), as well as ultrastable long-term stability (1000 cycles) with a satisfied specific capacity (535.6 mAh g^-1 ) at 1 A g^-1 . This work facilitates an in-depth understanding of the synergistic effect of vacancies and heterojunctions in improving the Na⁺ reaction kinetics, providing an effective strategy to the rational design of key materials for high efficiency rechargeable batteries.

Ether-based electrolytes for sodium ion batteries

Sodium-ion batteries (SIBs) are considered to be strong candidates for large-scale energy storage with the benefits of cost-effectiveness and sodium abundance. Reliable electrolytes, as ionic conductors that regulate the electrochemical reaction behavior and the nature of the interface and electrode, are indispensable in the development of advanced SIBs with high Coulombic efficiency, stable cycling performance and high rate capability. Conventional carbonate-based electrolytes encounter numerous obstacles for their wide application in SIBs due to the formation of a dissolvable, continuous-thickening solid electrolyte interface (SEI) layer and inferior stability with electrodes. Comparatively, ether-based electrolytes (EBEs) are emerging in the secondary battery field with fascinating properties to improve the performance of batteries, especially SIBs. Their stable solvation structure enables highly reversible solvent-co-intercalation reactions and the formation of a thin and stable SEI. However, although EBEs can provide more stable cycling and rapid sodiation kinetics in electrodes, benefitting from their favorable electrolyte/electrode interactions such as chemical compatibility and good wettability, their special chemistry is still being investigated and puzzling. In this review, we provide a thorough and comprehensive overview on the developmental history, fundamental characteristics, superiorities and mechanisms of EBEs, together with their advances in other battery systems. Notably, the relation among electrolyte science, interfacial chemistry and electrochemical performance is highlighted, which is of great significance for the in-depth understanding of battery chemistry. Finally, future perspectives and potential directions are proposed to navigate the design and optimization of electrolytes and electrolyte/electrode interfaces for advanced batteries.

Willow-Leaf-Like ZnSe@N-Doped Carbon Nanoarchitecture as a Stable and High-Performance Anode Material for Sodium-Ion and Potassium-Ion Batteries

ZnSe is regarded as a promising anode material for energy storage due to its high theoretical capacity and environment friendliness. Nevertheless, it is still a significant challenge to obtain superior electrode materials with stable performance owing to the serious volume change and aggregation upon cycling. Herein, a willow-leaf-like nitrogen-doped carbon-coated ZnSe (ZnSe@NC) composite synthesized through facile solvothermal and subsequent selenization process is beneficial to expose more active sites and facilitate the fast electron/ion transmission. These merits significantly enhance the electrochemical performances of ZnSe@NC for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). The obtained ZnSe@NC exhibits outstanding rate performance (440.3 mAh g^-1 at 0.1 A g^-1 and 144.4 mAh g^-1 at 10 A g^-1 ) and ultralong cycle stability (242.2 mAh g^-1 at 8.0 A g^-1 even after 3200 cycles) for SIBs. It is noted that 106.5 mAh g^-1 can be retained after 550 cycles and 71.4 mAh g^-1 is still remained after 1500 cycles at 200 mA g^-1 when applied as anode for PIBs, indicating good cycle stability of the electrode. The possible electrochemical mechanism and the ionic diffusion kinetics of the ZnSe@NC are investigated using ex situ X-ray diffraction, high-resolution transmission electron microscopy, and a series of electrochemical analyses.

Building Hierarchical Microcubes Composed of One-Dimensional CoSe2 @Nitrogen-Doped Carbon for Superior Sodium Ion Batteries

Designing and synthesizing highly stable anode materials with high capacity is critical for the practical application of sodium ion batteries (SIBs), however, to date, this remains an insurmountable barrier. The introduction of hierarchical architectures and carbon supports is proving an effective strategy for addressing these challenges. Thus, we have fabricated a hierarchical CoSe₂ @nitrogen-doped carbon (CoSe₂ @NC) microcube composite using the Prussian blue analogue Co₃ [Co(CN)₆ ]₂ as template. The rational combination of the unique hierarchical construction from one to three dimensions and a nitrogen-doped carbon skeleton facilitates sodium ion and electron transport as well as stabilizing the host structure during repeated discharge/charge processes, which contributes to its excellent sodium storage capability. As expected, the as-prepared CoSe₂ @NC composite delivered remarkable reversible capacity and ultralong cycling lifespan even at a high rate of 2.0 A g^-1 (384.3 mA h g^-1 after1800 loops) when serving as the anode material for SIBs. This work shows the great potential of the CoSe₂ -based anode for practical application in SIBs, and the original strategy may be extended to other anode materials.

Cation-exchange construction of ZnSe/Sb2Se3 hollow microspheres coated by nitrogen-doped carbon with enhanced sodium ion storage capability

Recently, anode materials with synergistic sodium storage mechanisms of conversion combined with alloying reactions for sodium ion batteries (SIBs) have received widespread attention due to their high theoretical capacities. In this work, through reacting with an appropriate concentration of Sb³⁺ ions and a simple carbonization process, hollow ZnSe/Sb₂Se₃ microspheres encapsulated in nitrogen-doped carbon (ZnSe/Sb₂Se₃@NC) are progressively synthesized based on a cation-exchange reaction, using polydopamine-coated ZnSe (ZnSe@PDA) microspheres as the precursor. Benefiting from the synergistic effects between the unique structure and composition characteristics, when serving as an anode material for SIBs, they result in higher sodium diffusion coefficients (8.7 × 10^-13-3.98 × 10^-9 cm² s^-1) and ultrafast pseudocapacitive sodium storage capability. Compared with ZnSe@NC and Sb₂Se₃@NCs exhibit, ZnSe/Sb₂Se₃@NC exhibits more stable capacity (438 mA h g^-1 at a current of 0.5 A g^-1 after 120 cycles) and superior rate performance (316 mA h g^-1 at 10.0 A g^-1). Our work provides a convenient method to construct high performance anodes with tunable composition and structure for energy storage.