Three-Dimensional
Nitrogen-Doped Carbonaceous Networks
Anchored with Cobalt as Separator Modification Layers for Low-Polarization
and Long-Lifespan Aluminum–Sulfur Batteries
posted on 2023-12-08, 12:40authored byCheng Xu, Maider Zarrabeitia, Yueliang Li, Johannes Biskupek, Ute Kaiser, Xu Liu, Stefano Passerini
Aluminum–sulfur (Al–S) batteries have attracted
extensive
interest due to their high theoretical energy density, inherent safety,
and low cost. However, severe polarization and poor cycling performance
significantly limit the development of Al–S batteries. Herein,
three-dimensional (3D) nitrogen-doped carbonaceous networks anchored
with cobalt (Co@CMel‑ZIF) is proposed as a separator
modification layer to mitigate these issues, prepared via carbonizations
of a mixture of ZIF-7, melamine, and CoCl2. It exhibits
a 3D network structure with a moderate surface area and high average
pore diameter, which is demonstrated to be effective in adsorbing
the aluminum polysulfides and hindering the mobility of polysulfides
across the separator for enhanced cyclic stability of Al–S
batteries. Meanwhile, Co@CMel‑ZIF are characterized
by abundant catalytic pyridinic-N and Co–Nx active sites that effectively eliminate the barrier of sulfides’
conversion and thereby facilitate the polarization reduction. As a
result, Al–S cells based on the separator modified with Co@CMel‑ZIF exhibit a low voltage polarization of 0.47 V
under the current density of 50 mA g–1 at 20 °C
and a high discharge specific capacity of 503 mAh g–1 after 150 cycles. In contrast, the cell employing a bare separator
exhibits a polarization of 1.01 V and a discharge capacity of 300
mAh g–1 after 70 cycles under the same conditions.
This work demonstrates that modifying the separators is a promising
strategy to mitigate the high polarization and poor cyclability of
Al–S batteries.