Crystal Structures and Cathode Properties of Chemically and Electrochemically Delithiated Li_xNi_0.5Mn_0.5O₂ with Applications to Mg Rechargeable Batteries

Abstract

Both electrochemically and chemically delithiated layered rock-salt Li x Ni 0.5 Mn 0.5 O 2 were successfully synthesized to investigate their crystal structures and cathode properties in the Mg rechargeable batteries. While the electrochemically delithiated Li x Ni 0.5 Mn 0.5 O 2 (x = 0.1 or 0.5) showed reversible behavior only two cycles in a Mg cell with subphase after initial discharge, the chemically delithiated Li 0.45 Ni 0.5 Mn 0.5 O 2 delivered a discharge capacity of 175 mAh g −1 with an average potential of 2.4 V vs Mg/Mg 2+ during several cycles. The chemically delithiated structure with x = 0.45 was found to be able to intercalate Mg ions according to the Rietveld analysis for synchrotron XRD patterns and XANES spectra for discharged electrode. It was concluded that the chemically delithiated Li 0.45 Ni 0.5 Mn 0.5 O 2 provided the favored structure for Mg intercalation due to the appropriate interlayer distance.

Phase Transition Behavior of MgMn2O4 Spinel Oxide Cathode during Magnesium Ion Insertion

“…Sulfide-based cathode materials, such as Chevrel − and thiospinel, − are capable of reversible insertion and extraction of magnesium ions, but their low capacity and potential make them difficult to construct high energy density batteries. Therefore, oxide materials such as V 2 O 5 , − MnO 2 , , polyanions, − layered rock-salt, , and spinels − have been developed toward achieving higher charge–discharge potentials and capacities than those of sulfide-based cathode materials.…”

The Quest for Functional Oxide Cathodes for Magnesium Batteries: A Critical Perspective

“…These studies are typically performed ex situ on fully discharged (reduced) and charged (oxidized) electrodes. A summary of >220 MOCs and analyses of chemical, redox, and structural changes with Mg electrochemistry is shown in Figure and described in Table 2 in the Supporting Information. − [Note: All abbreviations and acronyms used in this Perspective are defined in Table 1 in the Supporting Information. ]…”

Revisiting Delithiated Li_1.2Mn_0.54Ni_0.13Co_0.13O₂: Structural Analysis and Cathode Properties in Magnesium Rechargeable Battery Applications

“…We presumed that the NIP must contain more Li and exhibit lower valence states of its transition metals because of weakened O-O repulsion, which are generally characterized by layered rock-salt compounds. 8,9 Although interlayer distances could not be distinguished by TEM because of their close distances of the NIP: 1.39980/3 = 0.47 nm and the WIP: 1.4426/3 = 0.48 nm, we conducted TEM observations to confirm the layered rock-salt structure and to examine the homogeneity in metal distribution. The corresponding images show submicron particles (Fig.…”

“…The cathode properties of the Mg rechargeable battery are evaluated using both three-electrode cell and full-cell set-up. The composite cathode was prepared by grinding active material/SuperC65/PTFE in 5/5/1 weight ratio, previous reported composition, 5,6,[8][9][10] by agate mortar, then spread onto the Al-mesh current collector. For a three-electrode set-up, an AZ31 (Mg/Al/Zn of 96/3/1 weight ratio) foil and an Ag wire, were served as a counter and reference electrodes, respectively, and 0.3 M [Mg(G4)][TFSA] 2 /[PYR 13 ][TFSA] was used as an electrolyte.…”

“…7 There is no known oxide material that demonstrates both a high potential during discharge and a high discharge capacity of 300 mAh g ¹1 or greater like LIB cathode materials. Some potential candidates, such as LiMn 1/3 Ni 1/3 Co 1/3 O 2 , 8 LiMn 1/2 Ni 1/2 O 2 , 9 Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 -O 2 , 10 have already been reported as the cathode active materials for MRBs. Upon treating them with the NO 2 BF 4 oxidizer, the resulting delithiated materials allowed the comparable redox reaction even in MRBs to those in LIB.…”