Vacancy defect MoSeTe embedded in N and F co-doped carbon skeleton for high performance sodium ion batteries and hybrid capacitors

Abstract

Sodium-ion batteries (SIBs) and hybrid capacitors (SIHCs) have garnered significant attention in energy storage due to their inherent advantages, including high energy density, cost-effectiveness, and enhanced safety. However, developing high-performance anode materials to improve sodium storage performance still remains a major challenge. Here, a facile one-pot method has been developed to fabricate a hybrid of MoSeTe nanosheets implanted within the N,F co-doped honeycomb carbon skeleton (MoSeTe/N,F@C). Experimental results demonstrate that the incorporation of large-sized Te atoms into MoSeTe nanosheets enlarges the layer spacing and creates abundant anion vacancies, which effectively facilitate the insertion/extraction of Na+ and provide numerous ion adsorption sites for rapid surface capacitive behavior. Additionally, the heteroatoms N,F co-doped honeycomb carbon skeleton with a highly conductive network can restrain the volume expansion and boost reaction kinetics within the electrode. As anticipated, the MoSeTe/N,F@C anode exhibits high reversible capacities along with exceptional cycle stability. When coupled with Na3V2(PO4)3@C (NVPF@C) to form SIB full cells, the anode delivers a reversible specific capacity of 126 mA h g−1 after 100 cycles at 0.1 A g−1. Furthermore, when combined with AC to form SIHC full cells, the anode demonstrates excellent cycling stability with a reversible specific capacity of 50 mA h g−1 keeping over 3700 cycles at 1.0 A g−1. In situ XRD, ex situ TEM characterization, and theoretical calculations (DFT) further confirm the reversibility of sodium storage in MoSeTe/N,F@C anode materials during electrochemical reactions, highlighting their potential for widespread practical application. This work provides new insights into the promising utilization of advanced transition metal dichalcogenides as anode materials for Na+-based energy storage devices.