A theoretical and experimental study of hexagonal molybdenum trioxide as dual-ion electrode for rechargeable magnesium battery
Author
Cabello Bermúdez, Marta
Medina, Alejandro
Alcántara, Ricardo
Nacimiento-Cobos, Francisco José
Pérez-Vicente, C.
Tirado Coello, José Luis
Publisher
ElsevierDate
2020Subject
Magnesium batteriesPost-lithium
Supercapacitors
Anion intercalation
Computer simulations
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Show full item recordAbstract
The hexagonal polytype of molybdenum trioxide (h-MoO3) was prepared through the hydrothermal
method. The anisotropic growth of the particles yields to micro rods with prismatic geometry. Theoretical
calculations were carried out to simulate the insertion of magnesium in the framework of h-MoO3.
The electrochemical behavior of single-phase h-MoO3 in non-aqueous magnesium cells was studied, and
for that purpose, Mg metal or activated carbon (A.C.) was used as a counter electrode. This is the first
report about the insertion of a divalent cation into h-MoO3. The experimental capacity vs. Mg is only
around 20e50 mAh g 1. Nevertheless, whether Mg metal is replaced by A.C. as the counter electrode, the
electrochemical behavior of h-MoO3 is improved, and the reversible capacity is about 100 mAh g 1 after
130 cycles. The combination of h-MoO3 and A.C. forms a hybrid or asymmetric electrochemical capacitor.
The mechanism of the reaction in the working electrode is more complex than a Mg2þ-insertion. Anion
(TFSI ) adsorption and redox of oxygen ions in the lattice of h-MoO3 also contribute to the reversible
capacity. Consequently, h-MoO3 is a dual-ion electrode material. For higher mass ratio A.C./h-MoO3, the
experimental maximum reversible capacity is up to 350 mAh g 1 (equivalent to nominal composition
Mg0.94MoO3).