High-performance Li-ion batteries require materials with well-designed and controlled structures on nanometre and micrometre scales. Electrochemical properties can be enhanced by reducing crystallite size and by manipulating structure and morphology. Here we show a method for preparing hierarchically structured Li4Ti5O12 yielding nano- and microstructure well-suited for use in lithium-ion batteries. Scalable glycothermal synthesis yields well-crystallized primary 4–8 nm nanoparticles, assembled into porous secondary particles. X-ray photoelectron spectroscopy reveals presence of Ti+4 only; combined with chemical analysis showing lithium deficiency, this suggests oxygen non-stoichiometry. Electron microscopy confirms hierarchical morphology of the obtained material. Extended cycling tests in half cells demonstrates capacity of 170 mAh g−1 and no sign of capacity fading after 1,000 cycles at 50C rate (charging completed in 72 s). The particular combination of nanostructure, microstructure and non-stoichiometry for the prepared lithium titanate is believed to underlie the observed electrochemical performance of material.
Mercury and its compounds
are classified as very toxic and they
pose a real threat to human health. Coal combustion processes constitute
one of the main sources of mercury emission to the environment. The
use of hard coal by the nonindustrial combustion installations sector
(among others households) is a special issue. In contrast to large
coal-fired power plants, such users are not equipped with systems
for reducing emissions. For this group of users, it is necessary to
use hard coal with the lowest possible mercury content. In the paper,
a method for the production of hard coal with low mercury content
based on combined processes of dry deshaling and thermal pretreatment
is proposed. The proposed method allowed for a reduction of mercury
content in the analyzed coals from 43 to even 92% (in relation to
its lower heating value). The produced coals were characterized by
relatively low mercury contents from 1.5 to 4.8 μg/MJ with an
average of 2.4 μg/MJ. The application of this method may potentially
reduce the annual mercury emission from the Polish sector of nonindustrial
combustion installations by 0.365 Mg.
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