High‐Voltage Oxygen‐Redox‐Based Cathode for Rechargeable Sodium‐Ion Batteries

Abstract

SIBs), for which the reaction chemistries are similar to those of LIBs. [4][5][6][7][8] To reach similar energy densities as LIBs, promising cathode materials for SIBs must possess high capacity to compensate for their intrinsically low operation voltages. As the capacities of cathode materials can reach their limit when using transition metal redox, it is anticipated that redox of oxygen in the crystal structure can contribute additional capacity and boost the resulting energy density. [9,10] Representative works were performed in the early 2000s, specifically, on Li 2 MnO 3 (Li[Li 1/3 Mn 2/3 ]O 2 ) layered material, [11,12] which has the same crystal structure as typical LiTMO 2 (TM = transition metal). Li 2 MnO 3 is electrochemically inactive because Mn 4+ /Mn 5+ redox is not available within the normal cutoff voltage window. However, the material delivered a capacity beyond the theoretical limit attributed to the transition metal redox (300 mAh g −1 ). [12] Earlier works suggested that the delivered capacity could be attributed to oxygen loss from the oxide lattice; [12] however, state-of-the-art characterization later proved that the main contributor to the capacity was associated with the oxygen redox, [13] which triggered the intensive study of oxygen redox. Recently, there are some arguments to verify the chemical state of lattice oxygen during electrochemical reaction. Earlier work by Tarascon et al. [9] demonstrated the oxygen activity using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and electron paramagnetic resonance (EPR) in Li 2 Ru 1-y Sn y O 3 compound. In situ or operando Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) become important tools in identifying the formation of peroxolike species (O 2 n− ). [14,15] Yang and Devereaux [16] highlighted the importance of using resonant inelastic X-ray scattering (RIXS) to identify the activity of lattice oxygen in oxide materials. From the above facts, it is considered that combination of the above-mentioned characterization tools with theoretical thermodynamic prediction may provide more reliable results to understand the oxygen redox chemistry.The oxygen redox reaction has also been extensively investigated in SIBs to achieve additional capacity. [17][18][19] For SIBs, Na 2 MnO 3 (Na[Na 1/3 Mn 2/3 ]O 2 ), which has the same crystal structure as Li 2 MnO 3 , has also been considered despite the large difference in the ionic size between sodium and manganese. For Recently, anionic-redox-based materials have shown promising electrochemical performance as cathode materials for sodium-ion batteries. However, one of the limiting factors in the development of oxygen-redoxbased electrodes is their low operating voltage. In this study, the operating voltage of oxygen-redox-based electrodes is raised by incorporating nickel into P2-type Na 2/3 [Zn 0.3 Mn 0.7 ]O 2 in such a way that the zinc is partially substituted by nickel. As designed, the resulting P2-type Na 2/3 [(Ni 0.5 Zn 0.5 ) 0.3 Mn 0.7 ]O 2 electrode ...

A New Approach to Stable Cationic and Anionic Redox Activity in O3‐Layered Cathode for Sodium‐Ion Batteries

“…[22] For SIBs, the anionic redox reaction is available for not only Na-rich materials but also Na-deficient P2/P3-type compounds. [23][24][25][26][27][28][29][30][31][32][33][34][35] For example, manganese-based P2-type sodiumdeficient materials with low-valence substituents, such as Li, [26,30,31] Zn, [23,29] and Mg, [27,28] have demonstrated oxygenredox activity with good structural stability. It is generally accepted that a NaOA (A = Li, Na, Mg, Zn, or vacancy) local coordination environment is the essential requirement for oxygen redox activation in P2/O3 type layered Na x [ATM] O 2 (TM: transition metals).…”

Influence of Cosurfactant on the Synthesis of Surface‐Modified Na2/3Ni1/3Mn2/3O2 as a Cathode for Sodium‐Ion Batteries

“…Otherwise, reports on the redox mechanism implied in the high voltage plateau have pointed out to a combination of both Ni 4 + /Ni 2 + and O 2À /O 1À redox pairs . [29][30][31] The two plateaus below 4.0 V appear clearly split as a consequence of Na-vacancy rearrangement in the sodium layer. [32] The overall discharge capacity recorded for samples prepared by the emulsion method was higher irrespective of the nature of the cosurfactant molecules.…”

Sodium-Based Batteries: In Search of the Best Compromise Between Sustainability and Maximization of Electric Performance

“…To address this issue, the Ni was introduced to the crystal structure by substituting half of the Zn in structure (P2-Na 2/3 Mn 0.7 Zn 0.15 Ni 0.15 O 2 ). The addition of the Ni resulted in an increase in the operating potential to 3.5 V (Konarov et al, 2020). Among NASICON type of cathodes which shown in Figure 2, Na 3 V 2 (PO 4 ) 3 and its derivatives exhibited excellent electrochemical performance (Guo et al, 2017).…”