Lithium–sulfur
batteries (LSBs) have been considered as
one of the most promising energy storage systems because of their
high theoretical energy density. However, the “shuttle effect”
caused by polysulfide results in poor cycling stability and low electrochemical
properties, which strongly impedes the practical application of LSBs.
Herein, a kind of amphiphilic carborane-based covalent organic framework
(CB-COF) is synthesized and treated as nano-trappers for polysulfide.
The microporous CB-COFs show high-temperature resistance and excellent
chemical stability. Both experimental results and theoretical calculation
indicate the strong adsorption ability of CB-COF for polysulfides.
Such an ability makes CB-COF a candidate separator material for LSBs,
which efficiently suppresses the “shuttle effect,” leading
to a high-rate capacity (314 mA h g–1 after 1000
cycles at 2.5 C) and an ultra-long cycling life (after 1000 cycles
with a very low decay rate of 0.0395% per cycle at 1 C) of LSBs.
A novel method for the regioselective C2-chlorination of heterocyclic N-oxides has been developed. PPh 3 /Cl 3 CCN were used as chlorinating reagents and the desired N-heterocyclic chlorides were obtained smoothly in satisfactory yields. The reactions proceeded in a highly efficient and selective manner University
Vacancy engineering and morphology construction were integrated simultaneously by the self-assembly of melamine (MA) and cyanuric acid (CA) in the presence of P123 and H2SO4, which contributed to the hexagonal...
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