Identifying the anionic redox activity in cation-disordered Li_1.25Nb_0.25Fe_0.50O₂/C oxide cathodes for Li-ion batteries

Abstract

<p>Reversible lattice oxygen reaction, and irreversible oxygen release are clarified in high capacity cation-disordered Li_1.25Nb_0.25Fe_0.50O₂/C cathode for Li-ion batteries.</p>

Electrochemical Utilization of Iron IV in the Li1.3Fe0.4Nb0.3O2 Disordered Rocksalt Cathode

“…At 4.8 V, this peak is absent indicating the loss of these environments during further charging. Similar loss of the 528 eV pre‐edge feature at the end of charge were observed for the Fe‐based DRS system in previous studies [15,22] . This contrasts with the Mn‐based DRS cathodes that do not show a loss of bulk Mn 4+ ‐O peaks during the first charge [15] …”

“…[14,15] Novel Fe-based systems including Li 5 FeO 4, [16][17][18][19] Li 4 FeSbO 6 , [20] and cation-disordered Li 1.24 Fe 0.38 Ti 0.38 O 2 , [21] Li 1.3 Fe 0.4 Nb 0.3 O 2 , [15] and related compositions [22,23] have achieved reversible capacities over 200 mAh/g. As with LiFeO 2 , these systems often display rapid capacity fade [17,22] and Fe 2 + /3 + activation on cycling. [21,22] The overall stability of the alkali-rich Fe-based cathodes and their ability to achieve high energy densities will be dependent on the underlying redox mechanisms.…”

“…As with LiFeO 2 , these systems often display rapid capacity fade [17,22] and Fe 2 + /3 + activation on cycling. [21,22] The overall stability of the alkali-rich Fe-based cathodes and their ability to achieve high energy densities will be dependent on the underlying redox mechanisms. However, there remains uncertainty over the extent to which iron (Fe 3 + /4 + ) and oxygen (O 2À /nÀ ) contribute to the capacity of these cathode materials.…”

Experimental considerations to study Li-excess disordered rock salt cathode materials

“…32 Then, with further delithiation, oxygen starts to participate in the reaction as Fe 4+ is reduced back to Fe 3+ . 28,31 A follow up work is in preparation to assess the origin of the excess capacity in Li1.3Fe0.4Nb0.3O2. A erward, the material delivers a discharge capacity of 225.8 mA h g -1 .…”

In Situ/Operando (Soft) X‐ray Spectroscopy Study of Beyond Lithium‐ion Batteries

“…In the mapping of RIXS (mRIXS), a two-dimensional map of the excitation/emission energy and the emission intensity as a function of both the excitation and emission energy is probed. The oxygen K-edge mRIXS has been an important application in batteries, including O nin Li-rich cathode, [117,[120][121][122] oxidized oxygen species such as Li 2 O 2 and O 2 , [123][124][125] and O nin Na-ion battery cathodes. [66,67] As an example, spectroscopic studies regarding O 2 based on oxygen K-edge XAS and RIXS at particular excitation energies have been studied since decades ago.…”