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

Abstract

caused by the large Na + radius (1.02 Å) lead to undesirable electrochemical performance, including low capacity, poor rate capability and short life span, which plagued the wide-scale application of SIBs. [3] Thus, exploring suitable anodes with rational design and controllable preparation aiming to improve the kinetic of sodiation and desodiation is believed to be an essential task to realize the practical usage of SIBs.By virtue of conspicuous features including high theoretical capacity and intrinsic metallic property, transition metal selenides are regarded as promising anodes for SIBs. Generally, the Na + -storage process of transition metal selenides refers to the reaction between Na and transition metal selenides involving the total reduction of the transition metal to its metallic or alloy states and subsequently endowing the high theoretical capacity. [4] Compared to materials based on insertion Na + -storage mechanism (such as carbon anodes), transition metal selenides exhibit higher specific capacity and better safety by avoiding the formation of sodium dendrite in the low voltage area. While compared to the corresponding metal oxides and sulfides, transition metal selenides display more favorable reactivity benefiting from the weaker metal-Se bond and better conductivity of discharged product (Na 2 Se). [5] Nevertheless, every coin has two sides. The sluggish kinetics coupled with the huge volume expansion caused by the crystal structure destruction and new phases formation during the electrochemical reaction process, lead to the unsatisfied capacity and limited cycling life. Therefore, plenty of efforts, such as designing a novel structure to exposure more active sites, [6,7] coupling with carbon matrix to improve the conductivity, [3,8] modifying the electrolyte to reduce the reaction energy barrier, and so on, [9] have been made to address the issues mentioned above. Nevertheless, these strategies are mainly focused on the external charge transfer tailing, severe electrode polarization and sluggish Na + diffusion kinetic are still crucial obstacles for the achieving high-performance SIBs.Defects and interface engineering have been proved to be igneous strategies to improve the physical and chemical properties of materials, which have attracted wide interests in energy storage areas. [10][11][12][13] As a typical point defect, vacancies can boost the electrochemical performance of metal-ionThe 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, accel...

Self-assembled nanoflower-like FeSe2/MoSe2 heterojunction anode with enhanced kinetics for superior-performance Na-ion half/full batteries

“…The contribution ratios of the capacitive behavior of FMSe were calculated using the equation i ( v ) = k 1 v + k 2 v 1/2 . 51 The FMSe electrodes show a 59.01% capacitive contribution at 0.4 mV s −1 (Fig. 5c), and the capacitive contribution gradually increases with the scan rate as shown in Fig.…”

2D Metal–organic framework derived Co/CoSe2 heterojunctions with interfacial electron redistribution as bifunctional electrocatalysts for urea-assisted rechargeable Zn–air batteries

“…S6†), which consequently produces abundant active sites to enhance the catalytic activity. 46,47 The numerous defects and the Schottky barrier between CoSe 2 and metallic Co can effectively trap more oxygen intermediates and accelerate the electron transfer rate. 48 The HRTEM images show that the lattice spacings are 0.257 nm and 0.204 nm, which corresponds to the (111) lattice plane of CoSe 2 and the (111) lattice plane of Co (Fig.…”

Structural Stability Boosted in 3D Carbon‐Free Iron Selenide through Engineering Heterointerfaces with SeP Bonds for Appealing Na+‐Storage

“…The outstanding Na + -storage performance may be ascribed to the formation of well heterointerfaces with a strong FeP bond, which increases the stability of the heterostructure, enhances the conductivity, and accelerates the Na + diffusion kinetics. [11] On the other hand, the designed 3D porous network not only affords an unhindered channel for the fast transfer of Na + during the conversion reaction but also promotes the electron's transportation, contributing to the higher specific capacity.…”

“…Related work renders a new insight into advanced anodes with accelerated Na + diffusion kinetic and enhanced charge transfer efficiency for SIBs. [11] However, the previously reported work primarily focuses on designing nanostructured anodes with carbon materials, which always leads to a reduced tap density and subsequently decreased volumetric energy densities and Coulombic efficiency. Therefore, it is logical to develop an efficient strategy to prepare carbon-free transition metal selenide anodes with good conductivity, excellent structural stability, and high tap density to satisfy the practical application.…”

“…[8,9] However, the realization of satisfactory performance is hindered by the poor cycling stability caused by the drastic volume changes under multiple reactions and sluggish reaction kinetic originating from the slow Na + diffusion in the electrodes. [10,11] To address these problems, three effective strategies are commonly utilized. One is to design diverse nanostructures, such as core-shell or yolkshell nanostructures, [12,13] 3D nanoporous networks, [14] hollow nanostructures, [15,16] and so on.…”