An Electrosynthesized 3D Porous Molybdenum Sulfide/Graphene Film with Enhanced Electrochemical Performance for Lithium Storage

Abstract

Molybdenum sulfide/graphene composites are promising anode materials for lithium-ion batteries (LIBs). In this work, MoS /graphene composite film with an ideal 3D porous structure is developed via a facile and straightforward electrochemical route. The MoS nanoparticles are uniformly anchored on the graphene nanosheets that are randomly arranged, resulting in MoS /graphene composites with well-developed porous structure. Benefiting from such structure and the synergistic effect from two components, this material shows a high specific capacity over 1200 mA h g , an excellent rate performance, and superior cycling stability. The dominating pseudocapacitive behavior in Li storage contributes to the outstanding rate capacity. Importantly, this kind of novel material can be easily produced as 3D microelectrodes for microscaled LIBs that are highly demanded for autonomous microelectronic systems.

3D Metal‐Rich Cu7.2S4/Carbon‐Supported MoS2 Nanosheets for Enhanced Lithium‐Storage Performance

“…The XRD pattern of 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite showed diffraction peaks centered at 27.7°, 32.1°, 46.1°, 54.6°, which were corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) reflection planes of the Cu 7.2 S 4 (JCPDS: 72-1966). [13,17] X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition and oxidization states of the 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite ( Figure 2). Moreover, the XRD pattern of as-prepared Cu 7.2 S 4 /C nanocomposite was presented in Figure S2.…”

“…Additionally, the intensity of the XRD diffraction peaks of the nanocomposite and MoS 2 nanosheets were relatively weak, implying the low crystallinity of Cu 7.2 S 4 /C@MoS 2 nanocomposite and pure MoS 2 nanosheets. [13,17] X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition and oxidization states of the 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite ( Figure 2). The two peaks at 932.8 eV and 952.4 eV were characteristic for Cu 2p 3/2 and Cu 2p 1/2 in the high-resolution XPS spectrum of Cu 2p (Figure 2a), and the Cu 2p 3/2 spectrum could be fitted into two peaks at 932.7 eV (Cu + ) and 934.1 eV (Cu 2 + ).…”

“…The shape of the electrochemical impedance spectrum could be described as an oblique straight line in the low frequency region representing the Warburg impedance (Z w ), and a semi-circle corresponding to the high-frequency region representing the charge-transfer resistance (R ct ). [17,29,54,55] It could be noticed that the diameter of the semicircle for 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite electrode was much smaller than pure MoS 2 nanosheets electrode, indicating lower R ct for 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite with the existence of the metal-rich Cu 7.2 S 4 /C. Moreover, the EIS of 3D core-shell Cu 7.2 S 4 /C@MoS 2 nanocomposite was tested before cycling and after 100 cycles at current density of 1 A g À 1 (Figure 6b).…”

“…Among them, MoS 2 has a two-dimensional (2D) structure similar to graphene, and is deemed to be one of the most fascinating anode materials due to its high theoretical lithium storage capacity (670 mAh g À 1 ). [17] However, the practical application of the MoS 2 nanosheets as anode for LIBs is still limited by the following factors: First, the conductivity of MoS 2 nanosheets is usually very limited; [18,19] Next, it inevitably accompanies the serious volume change upon cycling owing to its conversion reaction mechanism. [15,16] At the same time, its low cost and environmental benignity have gained the attention of the majority of researchers when it was investigated as LIBs anode material.…”

“…[15,16] At the same time, its low cost and environmental benignity have gained the attention of the majority of researchers when it was investigated as LIBs anode material. [17] However, the practical application of the MoS 2 nanosheets as anode for LIBs is still limited by the following factors: First, the conductivity of MoS 2 nanosheets is usually very limited; [18,19] Next, it inevitably accompanies the serious volume change upon cycling owing to its conversion reaction mechanism. [20] These factors can lead to rapid capacity degradation and disappointed rate performance.…”