Molecular Storage of Mg Ions with Vanadium Oxide Nanoclusters

Abstract

Mg batteries have potential advantages in terms of safety, cost, and reliability over existing battery technologies, but their practical implementations are hindered by the lack of amenable high‐voltage cathode materials. The development of cathode materials is complicated by limited understandings of the unique divalent Mg2+ ion electrochemistry and the interaction/transportation of Mg2+ ions with host materials. Here, it is shown that highly dispersed vanadium oxide (V2O5) nanoclusters supported on porous carbon frameworks are able to react with Mg2+ ions reversibly in electrolytes that are compatible with Mg metal, and exhibit high capacities and good reaction kinetics. They are able to deliver initial capacities exceeding 300 mAh g−1 at 40 mA g−1 in the voltage window of 0.5 to 2.8 V. The combined electron microscope, spectroscopy, and electrochemistry characterizations suggest a surface‐controlled pseudocapacitive electrochemical reaction, and may be best described as a molecular energy storage mechanism. This work can provide a new approach of using the molecular mechanism for pseudocapacitive storage of Mg2+ for Mg batteries cathode materials.

In Operando Synchrotron Diffraction and in Operando X-ray Absorption Spectroscopy Investigations of Orthorhombic V2O5 Nanowires as Cathode Materials for Mg-Ion Batteries

“…For V2O5 aerogel, the uptake of 4 mol of Mg 2+ per mol V2O5 was demonstrated in a chemical magnesiation test 19 . In the past ten years, a lot of work 17,[20][21][22][23][24][25][26][27][28] has been done on the V2O5 as cathode materials for MIBs. However, up to now, only limited capacities have been achieved for this kind of cathode material in electrochemical cells with a Mg electrolyte.…”

Rationally Designed Vanadium Pentoxide as High Capacity Insertion Material for Mg‐Ion

“…The broadening of the peaks is due to slight amorphous nature of the discharged V 2 O 5 spheres, which is the signature of magnesiated V 2 O 5 , confirmed previously from scanning tunneling electron microscopy (STEM) and electron diffraction. [ 36 ] The broad hump at 40° is due to the presence of carbon in the composite slurry. In order to study the local disorder, Raman study is carried out in V 2 O 5 spheres after Mg +2 intercalation shown in Figure 4b that compares the Raman spectra of pristine V 2 O 5 and Mg +2 intercalated V 2 O 5 .…”

“…[ 48 ] The changes and also appearance of a major peak at ≈900 cm −1 due to the formation of a magnesiated V 2 O 5 (ε‐Mg 0.6 V 2 O 5 ) are well established from previous studies. [ 16,26,36 ] The Mg +2 ions are intercalated into the interlayers of the V 2 O 5 spheres and coordinated with the oxygen atom to form a magnesiated V 2 O 5 phase (ε‐Mg x V 2 O 5 ) after discharging, while after charging, it reverts back to its initial phase (α‐V 2 O 5 ). However, the extent of reversible Mg +2 ion intercalation/deintercalation depends entirely on the stability of the V 2 O 5 , which arises from tailored monodispersed morphology of the spherical V 2 O 5 .…”

“…Several works have been done on V 2 O 5 as cathode material for Mg batteries with anhydrous electrolyte, but limited in achieving stable and significant specific discharge capacity. [ 16,30,35–37 ] The studies clearly evident the choice of nanostructured materials and thin films of V 2 O 5 as promising strategy to overcome the sluggish mobility of Mg ions into the cathode. Recently Fu et al [ 26 ] demonstrated reversible Mg intercalation in V 2 O 5 nanowires with discharge capacity of 130 mA h g −1 at C/20 after few activation cycles using Mg(ClO 4 ) 2 and AN electrolyte with capacity retention of <30% after 100 cycles.…”

A Hollow-Structured Manganese Oxide Cathode for Stable Zn-MnO2 Batteries

“…However, with the rapid development of renewable energy plants, there is an extensive and urgent demand for energy storage technologies for large-scale smart grid applications, which require rechargeable battery systems with good cycling performance, low cost, high safety, and environmental friendliness. In searching for new chemistry beyond lithium-ion batteries, multivalent secondary batteries (Mg, Ca, Zn, and Al) have attracted tremendous research efforts, which could, in principle, deliver a higher energy density based on their multi-electron reaction mechanisms [ 1 , 2 ]. Among the multivalent batteries based on intercalation chemistries, aqueous rechargeable zinc ion batteries are considered as a promising candidate for large-scale energy storage applications because of their low cost and the large abundance of Zn [ 3 ].…”