The application of high‐performance silicon‐based anodes, which are among the most prominent anode materials, is hampered by their poor conductivity and large volume expansion. Coupling of silicon‐based anodes with carbonaceous materials is a promising approach to address these issues. However, the distribution of carbon in reported hybrids is normally inhomogeneous and above the nanoscale, which leads to decay of coulombic efficiency during deep galvanostatic cycling. Herein, we report a porous silicon‐based nanocomposite anode derived from phenylene‐bridged mesoporous organosilicas (PBMOs) through a facile sol–gel method and subsequent pyrolysis. PBMOs show molecularly organic–inorganic hybrid character, and the resulting hybrid anode can inherit this unique structure, with carbon distributed homogeneously in the Si‐O‐Si framework at the atomic scale. This uniformly dispersed carbon network divides the silicon oxide matrix into numerous sub‐nanodomains with outstanding structural integrity and cycling stability.
Electrocatalytic
denitrification is considered as the most promising
technology to transform nitrates to nitrogen gas in sewage so far.
Although noble metal-based catalysts as a cathode material have reached
decent removal capacity of nitrate, the high cost is the main hamper
of electrocatalytic reduction. Therefore, the development of alternative
catalysis toward highly effective denitrification is imperative yet
still remains a significant challenge. Herein, a corchorifolius-like
structure, where Fe nanoparticles are sealed in carbon microspheres
(CL-Fe@C) with a rough surface, has been elaborately designed by self-assemble
strategy. Impressively, the architectured CL-Fe@C microspheres are
surrounded with a lot of small iron nanoparticles and contain the
high iron content of ∼74%. As a result, an excellent removal
capacity of 1816 mg N/g Fe and a high nitrogen selectivity of 98%
under a very low nitrate concentration of 100 mg/L are achieved when
using the CL-Fe@C microspheres as electrocatalytic denitrification.
The present work not only explores high performance electrocatalysis
for the denitrification but also promote new inspiration for the preparation
of other iron-based functional materials for diverse applications.
Due
to the abundant potassium resource on the Earth’s crust,
researchers now have become interested in exploring high-performance
potassium-ion batteries (KIBs). However, the large size of K+ would hinder the diffusion of K ions into electrode materials, thus
leading to poor energy/power density and cycling performance during
the depotassiation/potassiation process. So, few-layered V5S8 nanosheets wrapping a hollow carbon sphere fabricated via a facile hollow carbon template induced method could
reversibly accommodate K storage and maintain the structure stability.
Hence, the as-obtained V5S8@C electrode enables
rapid and reversible storage of K+ with a high specific
capacity of 645 mAh/g at 50 mA/g, a high rate capability, and long
cycling stability, with 360 and 190 mAh/g achieved after 500 and 1000
cycles at 500 and 2000 mA/g, respectively. The excellent electrochemical
performance is superior to the most existing electrode materials.
The DFT calculations reveal that V5S8 nanosheets
have high electrical conductivity and low energy barriers for K+ intercalation. Furthermore, the reaction mechanism of the
V5S8@C electrode in KIBs is probed via the in operando synchrotron X-ray diffraction technique,
and it indicates that the V5S8@C electrode undergoes
a sequential intercalation (KV5S8) and conversion
reactions (K2S3) reversibly during the potassiation
process.
To accelerate the commercial implementation
of high-energy batteries,
recent research thrusts have turned to the practicality of Si-based
electrodes. Although numerous nanostructured Si-based materials with
exceptional performance have been reported in the past 20 years, the
practical development of high-energy Si-based batteries has been beset
by the bias between industrial application with gravimetrical energy
shortages and scientific research with volumetric limits. In this
context, the microscale design of Si-based anodes with densified microstructure
has been deemed as an impactful solution to tackle these critical
issues. However, their large-scale application is plagued by inadequate
cycling stability. In this review, we present the challenges in Si-based
materials design and draw a realistic picture regarding practical
electrode engineering. Critical appraisals of recent advances in microscale
design of stable Si-based materials are presented, including interfacial
tailoring of Si microscale electrode, surface modification of SiO
x
microscale electrode, and structural engineering
of hierarchical microscale electrode. Thereafter, other practical
metrics beyond active material are also explored, such as robust binder
design, electrolyte exploration, prelithiation technology, and thick-electrode
engineering. Finally, we provide a roadmap starting with material
design and ending with the remaining challenges and integrated improvement
strategies toward Si-based full cells.
A novel satellite-like structure of metal nanocrystals decorated on silicon@carbon core–shell nanoparticles achieves boosting of the initial coulombic efficiency.
This review summarizes the progress on four eco-friendly reduction techniques, including the detailed mechanism, reaction conditions, product morphology and electrochemical performance.
AbstractDespite the desirable progresses on various assembly tactics, the main drawback associated with current assemblies is the weak interparticle connections limited by their assembling protocols. Herein, we report a novel boron doping-induced interconnection-assembly approach for fabricating an unprecedented assembly of mesoporous silicon oxycarbide nanospheres which are derived from periodic mesoporous organosilicas. The as-prepared architecture is composed of interconnected, strongly coupled nanospheres with coarse surface. Significantly, through delicate analysis of the as-formed boron doped species, a novel melt-etching and nucleation-growth mechanism is proposed, which offers a new horizon for the developing interconnected assembling technique. Furthermore, such unique strategy shows precise controllability and versatility, endowing the architecture with tunable interconnection size, surface roughness, and switchable primary nanoparticles. Impressively, this interconnected assembly along with tunable surface roughness enables its intrinsically dual (both structural and interfacial) stable characteristics, achieving extraordinary long-term cycle life when used as lithium-ion battery anodes.
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