Recently, Sn 4 P 3 has emerged as a promising anode for sodium-ion batteries (SIBs) due to the high specific capacity. However, the use of Sn 4 P 3 has been impeded by capacity fade and an inferior rate performance. Herein, a biomimetic heterostructure is reported by using a simple hydrothermal reaction followed by thermal treatment. This bottlebrush-like structure consists of a stem-like carbon nanotube (CNT) as the electron expressway and mechanical support; fructus-like Sn 4 P 3 nanoparticles as the active material; and the permeable stoma-like thin carbon coating as the buffer layer. Having benefited from the biomimetic structure, a superior electrochemical performance is obtained in the SIBs. It exhibits a high capacity of 742 mA h g −1 after 150 cycles at 0.2C, and superior rate performance with 449 mA h g −1 at 2C after 500 cycles. Moreover, the sodium storage mechanism is confirmed by cyclic voltammetry and ex situ X-ray diffraction and transmission electron microscopy. In situ electrochemical impedance spectroscopy was adopted to analyze the reaction dynamics. This research represents a further step toward figuring out the inferior electrochemical performance of other metal phosphide materials.
Li–S batteries (LSBs) require a minimum 6 mAh
cm–2 areal capacity to compete with the state-of-the-art
lithium ion batteries (LIBs). However, this areal capacity is difficult
to achieve due to a major technical issue—the shuttle effect.
Nonpolar carbon materials limit the shuttle effect through physical
confinement. However, the polar polysulfides (PSs) only provide weak
intermolecular interactions (0.1–0.7 eV) with these nonpolar
carbon materials. The physically encapsulated PSs inside the nonpolar
carbon scaffold eventually diffuses out and starts shuttling. Chemically
interactive hosts are more effective at interacting with the PSs due
to high binding energies. Herein, a multifunctional separator coating
of nitrogen-doped multilayer graphene (NGN) and −SO3– containing Nafion (N-NGN) is used to mitigate
PS shuttling and to produce a high areal capacity LSB. The Nafion
is used as a binder instead of PVDF to provide an additional advantage
of −SO3– to chemically bind the
PS. The motive of this research is to investigate the effect of highly
electronegative N and −SO3– (N-NGN)
in comparison with the −OH, −COOH, and −SO3– groups from a hydroxyl graphene and Nafion
composite (N-OHGN) to mitigate PS shuttling in LSBs. The highly conductive
doped graphene architecture (N-NGN) provides efficient pathways for
both electrons and ions, which accelerates the electrochemical conversion
at high sulfur loading. Moreover, the electron-rich pyridine N and
−SO3– show strong chemical affinity
with the PS through polar–polar interactions, which is proven
by the superior electrochemical performance and density functional
theory calculations. Further, the N-NGN (5 h) produces a maximum areal
capacity of 12.0 and 11.0 mAh cm–2, respectively,
at 15 and 12 mg cm–2 sulfur loading. This areal
capacity limit is significantly higher than the required areal capacity
of LSBs for commercial application, which shows the significant strength
of N-NGN as an excellent separator coating for LSBs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.