Hierarchically designed MoWSe2/WO3/C anode for fast and efficient Na plus storage

Exploring anode materials with high energy and power density is one of the critical milestones in devel-oping sodium-ion batteries/capacitors (SIBs/SICs). Here, the Mo and W-based bimetallic organic frame-work (Mo-W-MOF) with core-shell structure is first formed by a facile strategy, followed by a selenization and carbonization strategy to finally prepare multileveled MoWSe2/WO3/C anode materials with core-shell petal like curled nanosheet structure. Between the petal (MoSe2)-core (WO3) structure, the formation of WSe2 flakes by partial selenization on the surface of WO3 serves as a heterogeneous con-nection between MoSe2 and WO3. The enlarged layer distance (0.677 nm) between MoSe2 and WSe2 can facilitate the rapid transfer of Na+ and electrons. The density functional theory (DFT) calculations verify that the MoWSe2/WO3/C heterostructure performs excellent metallic properties. Ex-situ X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) confirm the activation process from the initial insertion reaction to the later conversion reaction. Resultantly, when employed as the anode of SIBs, a remarkable capacity of 384.3 mA h g-1 after 950 cycles at 10 A g-1 is performed. Furthermore, the SICs assembled with commercial activated carbon (AC) as the cathode exhi-bits a remarkable energy density of 81.86 W h kg -1 (at 190 W kg -1) and 72.83 W h kg -1 (at 3800 W kg -1). The unique structural design and the reaction investigation of the electrode process can provide a refer-ence for the development of transition metal chalcogenides anodes.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, a Mo-W-MOF with core-shell structure was formed and transformed into a multileveled MoWSe2/WO3/C anode with a unique petal-like curled nanosheet structure. The electrode demonstrated excellent metallic properties and exhibited high capacity and energy density in sodium-ion batteries/capacitors, providing a reference for the development of transition metal chalcogenides anodes.