Vertically Oxygen-Incorporated MoS₂ Nanosheets Coated on Carbon Fibers for Sodium-Ion Batteries

Abstract

Developing a high-performance anode with high reversible capacity, rate performance, and great cycling stability is highly important for sodium-ion batteries (SIBs). MoS has attracted extensive interest as the anode for SIBs. Herein, the vertically oxygen-incorporated MoS nanosheets/carbon fibers are constructed via a facile hydrothermal method and then by simple calcination in air. Oxygen incorporation into MoS can increase the defect degree and expand the interlayer spacing. Vertical MoS nanosheet array coated on carbon fibers not only can expose rich active sites and reduce the diffusion distance of Na, but also improve the electronic conductivity and enhance structural stability. Meanwhile, interlayer-expanded MoS can decrease Na diffusion resistance and increase accessible active sites for Na. In this work, the electrode combining the oxygen-incorporated strategy with vertical MoS nanosheet-integrated carbon fibers displays high specific capacities of 330 mAh g over 100 cycles at a current density of 0.1 A g together with excellent rate behavior as the anode for SIBs. This strategy offers a helpful way for improving the electrochemical performance.

α‐Fe2O3 Nanoparticles Decorated C@MoS2 Nanosheet Arrays with Expanded Spacing of (002) Plane for Ultrafast and High Li/Na‐Ion Storage

“…The following equation between the peak current density ( i ) and the scan rate ( v ) can calculate qualitatively the degree of capacitive effectwhere, a and b are both constants. According to previous reports, the b value varies between 0.5 (diffusion‐controlled process) and 1 (capacitive behavior), which is determined by the slopes of log the current versus log the rate in Equation . The b values at different oxidation/reduction peaks range between 0.7 and 1.0 (Figure S12, Supporting Information), indicating that the capacitive storage contribution can't be overlooked during the redox processes of Fe 2 O 3 @C@MoS 2 nanosheet arrays, which leads to a fast Li + insertion/extraction.…”

“…The b values at different oxidation/reduction peaks range between 0.7 and 1.0 (Figure S12, Supporting Information), indicating that the capacitive storage contribution can't be overlooked during the redox processes of Fe 2 O 3 @C@MoS 2 nanosheet arrays, which leads to a fast Li + insertion/extraction. To further quantitatively determine the total Li‐ions capacitive contribution, the current can be separated to the pseudocapacitive effective ( k 1 v ) and the diffusion‐controlled process ( k 2 v 1/2 ) at a fixed potential ( V ) based the following equationswhere the k 1 and k 2 values can be calculated through plotting i ( V )/ v 1/2 versus i /v 1/2 (Equation ). As shown in Figure b, the capacitive contribution in the total charge for the Fe 2 O 3 @C@MoS 2 /CFC (gray region) is ≈73.5% at a scan rate of 0.5 mV s −1 , and the area of capacitive process is higher than the MoS 2 /CFC electrode (green region) (≈62.4%, the inset of Figure b).…”

Simple and Controllable Synthesis of Three‐Dimensional Spheroidal Structure of MoS2/rGO under Lower Temperature for Enhanced Properties in Lithium Battery

“…Figure a shows the constant current charge and discharge cycle performance curves of MoS 2 /rGO and MoS 2 at a current density of 100 mA g −1 . It can be seen that the initial discharge capacities of the MoS 2 /rGO and MoS 2 materials reached 992.5 mAh g −1 and 906.8 mAh g −1 .…”

Few-layer WS2nanosheets with oxygen-incorporated defect-sulphur entrapped by a hierarchical N, S co-doped graphene network towards advanced long-term lithium storage performances

“…33,34 The expanded interlayer spacing and few-layer feature can offer the more contact between WS 2 and electrolyte, facilitate insertion and extraction of Li + and shorten the transport paths of charge/ion during lithium storage process. 35,36 More importantly, O-DS-WS 2 nanosheets not only can reduce the band gap of WS 2 effectively to boost the intrinsic conductivity of WS 2 , but also disorder atomic arrangement to further generate defect (marked by yellow dotted circles) structures along with the increase of active sites. 33,[37][38][39] The selected-area electron diffraction (SAED) pattern of O-DS-WS 2 /NSG-800 displays a set of diffraction bright rings, indexed to different crystal planes (002), (101), (103) and (110) of 2H-WS 2 , respectively, indicating the high crystallinity of the O-DS-WS 2 /NSG-800 ( Fig.…”