4 research outputs found
Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries
The lithium (Li) metal anode suffers
severe interfacial instability
from its high reactivity toward liquid electrolytes, especially carbonate-based
electrolytes, resulting in poor electrochemical performance of batteries
that use 4 V high-capacity cathodes. We report a new skin-grafting
strategy that stabilizes the Li metal–liquid electrolyte interface
by coating the Li metal surface with polyÂ((<i>N</i>-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-<i>exo</i>-2,3-dicarboximide), a chemically and electrochemically
active polymer layer. This layer, composed of cyclic ether groups
with a stiff polycyclic main chain, serves as a grafted polymer skin
on the Li metal anode not only to incorporate ether-based polymeric
components into the solid-electrolyte interphase (SEI) but also to
accommodate Li deposition/dissolution under the skin in a dendrite/moss-free
manner. Consequently, a Li-metal battery employing a Li metal anode
with the grafted skin paired with LiNi<sub>0.5</sub>Co<sub>0.2</sub>Mn<sub>0.3</sub>O<sub>2</sub> cathode has a 90.0% capacity retention
after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm<sup>2</sup> in a carbonate-based electrolyte. This proof-of-concept study
provides a new direction for regulating the interfacial chemistry
of Li metal anodes and for enabling high-performance Li-metal batteries
Electrolysis of Gaseous CO<sub>2</sub> to CO in a Flow Cell with a Bipolar Membrane
The
conversion of CO<sub>2</sub> to CO is demonstrated in an electrolyzer
flow cell containing a bipolar membrane at current densities of 200
mA/cm<sup>2</sup> with a Faradaic efficiency of 50%. Electrolysis
was carried out by delivering gaseous CO<sub>2</sub> at the cathode
with a silver catalyst integrated in a carbon-based gas diffusion
layer. Nonprecious nickel foam in a strongly alkaline electrolyte
(1 M NaOH) was used to mediate the anode reaction. While a configuration
where the anode and cathode were separated by only a bipolar membrane
was found to be unfavorable for robust CO<sub>2</sub> reduction, a
modified configuration with a solid-supported aqueous layer inserted
between the silver-based catalyst layer and the bipolar membrane enhanced
the cathode selectivity for CO<sub>2</sub> reduction to CO. We report
higher current densities (200 mA/cm<sup>2</sup>) than previously reported
for gas-phase CO<sub>2</sub> to CO electrolysis and demonstrate the
dependence of long-term stability on adequate hydration of the CO<sub>2</sub> inlet stream
Controlled Exfoliation of MoS<sub>2</sub> Crystals into Trilayer Nanosheets
The controlled exfoliation of transition
metal dichalcogenides
(TMDs) into pristine single- or few-layer nanosheets remains a significant
barrier to fundamental studies and device applications of TMDs. Here
we report a novel strategy for exfoliating crystalline MoS<sub>2</sub> into suspensions of nanosheets with retention of the semiconducting
2H phase. The controlled reaction of MoS<sub>2</sub> with substoichiometric
amounts <i>n</i>-butylÂlithium results in intercalation
of the edges of the crystals, which are then readily exfoliated in
a 45 vol % ethanol–water solution. Surprisingly, the resulting
colloidal suspension of nanosheets was found (by electron microscopy
and atomic force microscopy) to consist mostly of trilayers. The efficiency
of exfoliation of the pre-intercalated sample is increased by at least
1 order of magnitude relative to the starting MoS<sub>2</sub> microcrystals,
with a mass yield of the dispersed nanosheets of 11–15%
Fast and Efficient Preparation of Exfoliated 2H MoS<sub>2</sub> Nanosheets by Sonication-Assisted Lithium Intercalation and Infrared Laser-Induced 1T to 2H Phase Reversion
Exfoliated 2H molybdenum disulfide
(MoS<sub>2</sub>) has unique properties and potential applications
in a wide range of fields, but corresponding studies have been hampered
by the lack of effective routes to it in bulk quantities. This study
presents a rapid and efficient route to obtain exfoliated 2H MoS<sub>2</sub>, which combines fast sonication-assisted lithium intercalation
and infrared (IR) laser-induced phase reversion. We found that the
complete lithium intercalation of MoS<sub>2</sub> with butyllithium
could be effected within 1.5 h with the aid of sonication. The 2H
to 1T phase transition that occurs during the lithium intercalation
could be also reversed by IR laser irradiation with a DVD optical
drive