Lithium–sulfur
(Li–S) batteries are severely hindered
by the low sulfur utilization and short cycling life, especially at
high rates. One of the effective solutions to address these problems
is to improve the sulfiphilicity of lithium polysulfides (LiPSs) and
the lithiophilicity of the lithium anode. However, it is a great challenge
to simultaneously optimize both aspects. Herein, by incorporating
the merits of strong absorbability and high conductivity of SnS with
good catalytic capability of ZnS, a ZnS-SnS heterojunction coated
with a polydopamine-derived N-doped carbon shell (denoted as ZnS-SnS@NC)
with uniform cubic morphology was obtained and compared with the ZnS-SnS2@NC heterostructure and its single-component counterparts
(SnS@NC and SnS2@NC). Theoretical calculations, ex situ XANES, and in situ Raman spectrum
were utilized to elucidate rapid anchoring-diffusion-transformation
of LiPSs, inhibition of the shuttling effect, and improvement of the
sulfur electrochemistry of bimetal ZnS-SnS heterostructure at the
molecular level. When applied as a modification layer coated on the
separator, the ZnS-SnS@NC-based cell with optimized lithiophilicity
and sulfiphilicity enables desirable sulfur electrochemistry, including
high reversibility of 1149 mAh g–1 for 300 cycles
at 0.2 C, high rate performance of 661 mAh g–1 at
10 C, and long cycle life with a low fading rate of 0.0126% each cycle
after 2000 cycles at 4 C. Furthermore, a favorable areal capacity
of 8.27 mAh cm–2 is maintained under high sulfur
mass loading of 10.3 mg cm–2. This work furnishes
a feasible scheme to the rational design of bimetal sulfides heterostructures
and boosts the development of other electrochemical applications.
Lithium–sulfur (Li–S) batteries have been hindered by the shuttle effect and sluggish polysulfide conversion kinetics. Here, a P‐doped nickel tellurium electrocatalyst with Te‐vacancies (P⊂NiTe2−x) anchored on maize‐straw carbon (MSC) nanosheets, served as a functional layer (MSC/P⊂NiTe2−x) on the separator of high‐performance Li–S batteries. The P⊂NiTe2−x electrocatalyst enhanced the intrinsic conductivity, strengthened the chemical affinity for polysulfides, and accelerated sulfur redox conversion. The MSC nanosheets enabled NiTe2 nanoparticle dispersion and Li+ diffusion. In situ Raman and ex situ X‐ray absorption spectra confirmed that the MSC/P⊂NiTe2−x restrained the shuttle effect and accelerated the redox conversion. The MSC/P⊂NiTe2−x‐based cell has a cyclability of 637 mAh g‐1 at 4 C over 1800 cycles with a degradation rate of 0.0139% per cycle, high rate performance of 726 mAh g‐1 at 6 C, and a high areal capacity of 8.47 mAh cm‐2 under a sulfur configuration of 10.2 mg cm‐2, and a low electrolyte/sulfur usage ratio of 3.9. This work demonstrates that vacancy‐induced doping of heterogeneous atoms enables durable sulfur electrochemistry and can impact future electrocatalytic designs related to various energy‐storage applications.
This study demonstrates
quick and efficient removal of different
dyes from wastewater by using MoS2/CuS nanosheet composites
(NCs) as adsorbent. The MoS2/CuS NCs are prepared by a
facile hydrothermal route, and the composites exhibit high adsorption
capacity with 273.23, 432.68, 98.78, and 211.18 mg/g for rhodamine
B (RhB), methylene blue (MB), methyl orange (MO), and rhodamine 6G
dyes (RhB 6G), respectively. This is ascribed to its high specific
surface area (106.27 m2/g) and small mesopores (2.299 nm)
which provide numerous adsorption sites and uniform coverage for dye
molecules. High adsorption efficiency is obtained for RhB (93.8%),
MB (100%), and RhB 6G (84.73%), except for MO (48.9%) at the adsorption
equilibrium time at the solution concentration of 80 mg/L. The adsorption
of MoS2/CuS NCs can be well described by the pseudo-second-order
kinetic model, and the adsorption isotherm at the equilibrium fits
well with the Langmuir model. The rapid and efficient adsorption ensures
MoS2/CuS NCs to be a broad-spectrum adsorbent for different
dye contaminants in water.
Lithium–sulfur (Li–S)
batteries featuring high-energy
densities are identified as a hopeful energy storage system but are
strongly impeded by shuttle effect and sluggish redox chemistry of
sulfur cathodes. Herein, annealed melamine foam loaded 2H/1T MoS2 (CF@2H/1T MoS2) is prepared as a multifunctional
interlayer to inhibit the shuttle effect, improve redox kinetics,
and reduce the charge–discharge polarization of Li–S
batteries. The CF@2H/1T MoS2 becomes fragmented structures
after assembling the cell, which not only benefits to adsorb and catalyze
LiPSs but also to significantly buffer the volume expansion due to
a large number of gaps between fragmented structures. Meanwhile, the
batteries based on CF@2H/1T MoS2 interlayer delivers high
areal capacity of 5.1 mAh cm–2 under high sulfur
mass loading of 7.6 mg cm–2 at 0.2 C. Importantly,
the experiments of in situ Raman spectra demonstrate
that the CF@2H/1T MoS2 can obviously inhibit the shuttle
effect by effectively adsorbing and catalyzing LiPSs. This novel design
idea and low-cost melamine foam raw material open up a new way for
the application of high-energy density Li–S batteries.
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