Carbon-Stabilized Interlayer-Expanded Few-Layer MoSe₂ Nanosheets for Sodium Ion Batteries with Enhanced Rate Capability and Cycling Performance

Abstract

Sodium ion batteries (SIBs) have been considered as a promising alternative to lithium ion batteries, owing to the abundant reserve and low-cost accessibility of the sodium source. To date, the pursuit of high-performance anode materials remains a great challenge for the SIBs. In this work, carbon-stabilized interlayer-expanded few-layer MoSe₂ nanosheets (MoSe₂@C) have been fabricated by an oleic acid (OA) functionalized synthesis-polydopamine (PDA) stabilization-carbonization strategy, and their structural, morphological, and electrochemical properties have been carefully characterized and compared with the carbon-free MoSe₂. When evaluated as anode for sodium ion half batteries, the MoSe₂@C exhibits a remarkably enhanced rate capability of 367 mA h g^-1 at 5 A g^-1, a high reversible discharge capacity of 445 mA h g^-1 at 1 A g^-1, and a long-term cycling stability over 100 cycles. To further explore the potential applications, the MoSe₂@C is assembled into sodium ion full batteries with Na₃V₂(PO₄)₃ (NVP) as cathode materials, showing an impressively high reversible capacity of 421 mA h g^-1 at 0.2 A g^-1 after 100 cycles. Such results are primarily attributed to the unique carbon-stabilized interlayer-expanded few-layer MoSe₂ nanosheets structure, which facilitates the permeation of electrolyte into the inner of MoSe₂ nanosheets, promoting charge transfer efficiency among MoSe₂ nanosheets, and accommodating the volume change from discharge-charge cycling.