Uniform Metal Sulfide@N‐doped Carbon Nanospheres for Sodium Storage: Universal Synthesis Strategy and Superior Performance

Abstract

Nitrogen‐doped carbon‐coated transition‐metal sulfides (TMS@NCs) have been considered as efficient anodes for sodium‐ion batteries. However, the uncontrollable morphology and weak core–shell binding forces significantly limit the sodium storage performance and life. Herein, based on the reversible ring‐opening reaction of the epoxy group of the tertiary amino group‐rich epoxide cationic polyacrylamide (ECP) at the beginning of hydrothermal process (acidic environment) and the irreversible ring‐opening (cross‐linking reactions) at the late hydrothermal period (alkaline environment), 47 nm‐sized ZnS@NCs were prepared via a one‐pot hydrothermal process. During this process, the covalent bonds formed between the ZnS core and elastic carbon shell significantly improved the mechanical and chemical stabilities of ZnS@NC. Benefiting from the nanosize, fast ion/electron transfer, and high stability, ZnS@NC exhibited a high reversible capacity of 421.9 mAh g−1 at a current density of 0.1 A g−1 after 1000 cycles and a superior rate capability of 273.8 mAh g−1 at a current density of 5 A g−1. Moreover, via this universal synthesis strategy, a series of TMS@NCs, such as MoS2@NC, NiS@NC, and CuS@NC were developed with excellent capacity and cyclability.

Poloxamer Pre-solvation Sheath Ion Encapsulation Strategy for Zinc Anode–Electrolyte Interfaces

“…A small crystal grains mean a large specific surface area, which can enhance the reaction activity of the electrode surface by reducing the reaction barrier. 32 Moreover, the overproduction of irreversible insulating products ((Zn-(OH) 2 ) 3 (ZnSO 4 )(H 2 O) 5 ) is evident for ZnSO 4 (Figure S23b), which undesirably accelerate the deactivation of the Zn electrode. 33 In stark contrast, after the addition of the poloxamer, the irreversible overproduction phase has disappeared, which may be due to the poloxamer changing the surface environment of the Zn electrode, leading to the convergent growth of zinc sulfate hydroxide hydrate.…”

“…Further calculations based on the Scherrer formula reveal that the addition of poloxamer reduces the grain size of the deposited Zn to half that of ZnSO 4 . A small crystal grains mean a large specific surface area, which can enhance the reaction activity of the electrode surface by reducing the reaction barrier . Moreover, the overproduction of irreversible insulating products ((Zn­(OH) 2 ) 3 (ZnSO 4 )­(H 2 O) 5 ) is evident for ZnSO 4 (Figure S23b), which undesirably accelerate the deactivation of the Zn electrode .…”

Perspective of Vanadium Disulfide: A Rising Star Finds Plenty of Room in Single and Multielectron Energy Storage

“…In addition, doping heteroatoms (usually nitrogen, N) can improve the reaction activity of carbon, and the high affinity of doped N for transition metals (TMs) can form a strong coupling with vanadium-based compounds, showing extraordinary electrochemical performance. − As an example, Liu et al prepared shuttle-like VS 2 nanocrystals grown on the layer of N-doped carbon. The strong interface interaction between N-doped carbon significantly improves the charge transfer dynamics and stability of the electrode.…”

Nitrogen doping induced by intrinsic defects of recycled polyethylene terephthalate‐derived carbon nanotubes

“…doping is highly desired, because it can offer more reaction sites and tune the electronic properties of carbonaceous materials. [9][10][11][12][13][14] However, it is noted that the current approach to making N-doped graphene/CNTs requires high-temperature calcination under an NH 3 atmosphere, 15,16 which is environmentally hazardous and uneconomical.…”