Exploring the insertion properties of Mg2+ in H2V3O8 as a function of the water content in the organic electrolyte

Exploring the Insertion Mechanisms of Metal Cations into V3O7·H2O

“…First, we compare the maximum discharge capacity and the corresponding inserted ion equivalents of Na + , Li + , and Zn 2+ during the first cycle, as listed in Table 1. Since the analysis of Zn 2+ insertion into HVO suggested that the presence of water in the electrolyte plays a crucial role for the maximum discharge capacities, we include Mg 2+ insertion in pure and water-containing organic electrolyte in the comparison, as reported by Sollinger et al 40 However, in the case of Mg 2+ insertion, the second cycle is used for comparing to the first cycle of Na + , Li + , and Zn 2+ insertion, because the carbon The Journal of Physical Chemistry C pellet replacing the Mg anode in the Mg cell is likely to contribute to the first cycle. Considering that Zn 2+ reaches the highest capacities of all ions and that Mg 2+ capacities improve considerably upon adding water to the organic electrolyte, we conclude that water-assisted ion insertion into HVO leads to improved capacities for divalent ions.…”

“…This increase of the in-plane parameters is rationalized with the reduction of the metal ions (here from V 5+ to V 4+ from V 4+ to V 3+ ), leading to larger ionic radii. 40 The changes in the unit cell parameters induce changes in the unit cell volume. While Na + insertion leads to an expansion during SS1, all other cases show a contraction in cell volume with respect to HVO at the OCV (see Table S1).…”

“…In addition, we compare these insertions mechanisms to Mg 2+ insertion into HVO, which has been reported by Sollinger et al using a similar experimental setup. 40 By detailed XRD analysis, we show as a function of the insertion ion to which extent lattice parameters change during charge and discharge and in which composition range solid solution and two-phase processes occur. Furthermore, we analyze how these structural changes correlate with the number and type of inserted ions and/or the state of charge.…”

“…Maximal Capacity, Inserted Ion Equivalents, Maximal Lattice Breathing (ΔV max ), and Unit Cell Parameters in % Referenced to the HVO Unit Cell at OCV a All values are obtained during the first or, in the case of Mg 2+ , the second discharge. The Mg 2+ values are taken from Sollinger et al40 …”

Structural, Morphological and Interfacial Investigation of H2V3O8 upon Mg2+ Intercalation

“…Indeed, once a water-free electrolyte was used, a significantly lower specific capacity of only about 80 mAh g À 1 was obtained at room temperature. [29] Very recently Söllinger et al [37] reported the electrochemical performance and operando XRD of HVO in Mg(ClO 4 ) 2 -based electrolytes with different amounts of water. It was demonstrated that the capacity of the materials increases with increasing amount of water in the electrolyte.…”