Heterogeneous Structured Bi₂S₃/MoS₂@NC Nanoclusters: Exploring the Superior Rate Performance in Sodium/Potassium Ion Batteries

Abstract

Bismuth-based materials have attracted increasing attention in the research field of sodium/potassium-ion batteries owing to the high theoretical capacity. Unfortunately, the large volume variation and poor electrical conductivity limit their electrochemical performance and applications. Herein, we report a composite of heterostructured Bi 2 S 3 /MoS 2 encapsulated in nitrogen-doped carbon shell (BMS@NC) obtained by a solvothermal reaction as a novel anode material for sodium/potassium-ion batteries. The coating of the carbon layer could effectively relieve structural strains stemmed from the large volume change and improve electrical conductivity. More importantly, by skillfully constructing the heterostructure, an internal electric field formed on the heterointerface provides a rapid diffusion of ion and charge. As a consequence, the BMS@NC composite showed an excellent electrochemical performance for both sodium-ion batteries (a capacity of 381.5 mA h g −1 achieved at a current density of 5.0 A g −1 and 412 mA h g −1 at 0.5 A g −1 after 400 cycles) and potassium-ion batteries (a high specific capacity of 382.8 mA h g −1 achieved after 100 cycles at 0.1 A g −1 ). The design of the Bi 2 S 3 /MoS 2 heterostructure provides an effective strategy to develop energy storage materials with good electrochemical properties.

In‐situ Nano‐Crystallization and Solvation Modulation to Promote Highly Stable Anode Involving Alloy/De‐alloy for Potassium Ion Batteries

“…0.4 Vi n5 Me lectrolyte,a nd an average K + diffusion coefficient (D K þ )o f7 .12 10 À12 cm 2 s À1 was achieved based on Fickss econd law (Supporting Information), which was comparable with the previous result. [16,22] Ther esults in 3M and 1Melectrolyte displayed similar trend with that of 5M case (Supporting Information, Figure S26b,26c), while the stable D K þ evolution during potassiation in 5M electrolyte evidenced the enhanced stability of electrochemical behaviors,a nd the narrowed potential hysteresis illustrated in the Supporting Information, Figure S27a-c during the whole potassiation/de-potassiation suggested more favorable electrochemical reaction in 5M electrolyte than the other two cases.T he BCO electrodes also achieved more flexible resistance variation in 5M electrolyte during alloy/de-alloy processes (Supporting Information, Figure S27d-f). Compared with the other two counterparts,i ts high resistance in the slop process during potassiation/de-potassiation could be attributed to accommodation for volume change of the electrode.…”

“…69 %w as achieved at current density of 0.025 Ag À1 ,b ased on an initial discharge capacity of 1068 mAh g À1 and charge capacity of 737 mAh g À1 ,and the long irreversible plateau during initial discharge could be mainly attributed to SEI formation. [14][15][16] Thed ischarged capacity outperformed theoretical value during the initial cycles,a nd SEI rebuilding was considered to be responsible for this phenomenon. As illustrated in the Supporting Information, Figure S3a, an in situ nanosized-crystallization of the 2D nano-sheet can be observed, where the 2D nanosheet block transformed into integration of small particles with average size of around 10 nm, and the whole flower-like structure was well maintained.…”

Enhanced Sodium‐Ion Storage Performance of a 2D MoS2 Anode Material Coated on Carbon Nanotubes

“…Moreover, during the sodiation/desodiation process the large volume expansion of MoS 2 layers can lead to serious pulverization of active materials and causes fast capacity decay [18–21] . Various strategies have been formulated, to address the above issues, including using some conductive carbon materials as a matrix to enhance electronic conductivity, broadening the interlayer distance of MoS 2 , as well as regulating the morphology at nanoscale to reduce the stress caused by the volume change [22–24] …”

Carbon-Interlayer SnO2–Sb2O3 Composite Core–Shell Structure Anodes for Sodium-Ion Batteries

“…The spectrum of Figure 4B clearly shows the characteristic peaks of D and G band located at 1,342 and 1,590 cm −1 , respectively, which corresponding to typical in-plane vibration of sp 2 -bonded carbon atoms and vibrational modes from sp 3 -bonded carbon atoms in amorphous carbon (Sevilla and Fuertes, 2009). The peak intensity ratio (I D /I G ) is 1.03, indicating that the carbon in SnO 2 @ C@Sb 2 O 3 is highly disordered, which is conducive to improving the electrochemical activity of electrode materials (Sun et al, 2019;Qin et al, 2020).…”

“…The working mechanism of SnO 2 @C@Sb 2 O 3 as the anode of SIBs is shown in Figure 8. The surface of the submicrospheres with multilayer core-shell structure is most likely to contact and react with the electrolyte, and the core can fully contact with the electrolyte after several cycles, which is an activation process (Zu et al, 2017;Sarkar et al, 2019;Zhang et al, 2019;Qin et al, 2020). Therefore, the cycle curve of SnO 2 @C@Sb 2 O 3 anode shows a trend of first decreasing and then increasing.…”