1. Role of Cu current collector on electrochemical mechanism of Mg–S batteryAna Robba, Maja Mežnar, Alen Vižintin, Jan Bitenc, Jernej Bobnar, Iztok Arčon, Anna Randon-Vitanova, Robert Dominko, 2020, original scientific article Abstract: Development of magnesium sulfur battery is accompanied with all known difficulties present in Li–S batteries,
however with even more limited choice of electrolytes. In the present work, the influence of current collector on
electrochemical mechanism was investigated in light of different reports where improved behavior was ascribed
to electrolyte. Notable differences in cycling behavior are reported when Al current collector is replaced by Cu
current collector independent of electrolyte. The initial reduction of sulfur follows similar reaction path no mater
of current collector, but formation of MgS can be in competition with formation of CuS in the presence of Cu
cations. With the subsequent cycling cells prepared from cathodes deposited on Cu current collector show
decrease in the voltage and formation of single plateau during cycling. The change corresponds to the
involvement of Cu into the reaction and formation of redox couple Mg/CuS as determined by Cu K-edge XANES
measurements. Corrosion of Cu foil is identified by SEM and serves as a source of Cu cations for the chemical
reaction between Cu and polysulfides. Mg/CuS redox couple shows improved cycling stability, but theoretical
energy density is severely reduced due to substitution of S with CuS as cathode active material.
Keywords: Magnesium
Sulfur
Rechargeable batteries
Current collector
Copper
Corrosion
Published in RUNG: 16.01.2020; Views: 3588; Downloads: 0
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2. A Mechanistic Study of Magnesium Sulfur BatteriesAna Robba, Alen Vižintin, Jan Bitenc, Gregor Mali, Iztok Arčon, Matjaž Kavčič, Matjaž Žitnik, Klemen Bučar, Giuliana Aquilanti, Charlotte Martineau-Corcos, Anna Randon-Vitanova, Robert Dominko, 2017, original scientific article Abstract: Magnesium sulfur batteries are considered as attractive energy storage devices due to the
abundance of electrochemically active materials and high theoretical energy density. Here we
report the mechanism of a Mg-S battery operation, which was studied in the presence of
simple and commercially available salts dissolved in a mixture of glymes. The electrolyte
offers high sulfur conversion into MgS in the first discharge with low polarization. The
electrochemical conversion of sulfur with magnesium proceeds through two well-defined
plateaus, which correspond to the equilibrium between sulfur and polysulfides (high-voltage
plateau) and polysulfides and MgS (low-voltage plateau). As shown by XANES, RIXS and
NMR studies, the end discharge phase involves MgS with Mg atoms in a tetrahedral
environment resembling the wurtzite structure, while chemically synthesized MgS crystalizes
in the rock-salt structure with octahedral coordination of magnesium.
Keywords: magnesium, sulfur, rechargeable batteries, XAS, NMR
Published in RUNG: 19.10.2017; Views: 5127; Downloads: 0
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