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

Abstract

<p>Correction for ‘Identifying the anionic redox activity in cation-disordered Li_1.25Nb_0.25Fe_0.50O₂/C oxide cathodes for Li-ion batteries’ by Mingzeng Luo <italic>et al.</italic>, <italic>J. Mater. Chem. A</italic>, 2020, <bold>8</bold>, 5115–5127, DOI: 10.1039/C9TA11739C.</p>

Compatibility of Various Electrolytes with Cation Disordered Rocksalt Cathodes in Lithium Ion Batteries

“…Thereby, the peak at ≈ 2.4 V can be attributed only to the cationic redox process in which Fe 2+ is oxidized to Fe 3+ . The redox mechanism behind the peak at a potential of 4.2 V vs Li|Li + is more complex and involves the oxidation of Fe 3+ to Fe 4+ , oxidation of O 2– to O δ− and O 2 , and the subsequent reduction of Fe 4+ back to Fe 3+ via a reductive coupling mechanism . The Fe 2+ |Fe 3+ redox peak stays constant in intensity and potential for both electrolytes, with the only exception being that it shifts to slightly lower intensity and a higher potential at the 100th cycle in the carbonate-based electrolyte.…”

“…The Li-ion transport through DRX materials is facilitated by a percolating network of 0-TM transport channels present in these materials above a specific lithium threshold. , This discovery led to the study of a vast amount of possible synergies between different TMs, which then inspired the development of new chemistries for cathode application. − In recent years, the combination of a redox active TM with Nb as an inactive d 0 stabilizer has been discussed and evaluated. , Different TM choices thereby result in distinct and complex charge compensation mechanisms involving either sole cationic redox reactions or the combination of them and various degrees of anionic contribution to the material capacity. Research focus so far has been on the understanding of these intricate redox processes and the factors influencing them . Little attention has been paid to the interactions between DRX materials and other components of a battery cell, for example, the electrolyte, the anode, and so on.…”

“…It is still unclear if the relatively high potentials of the anionic redox displayed by these materials and the consequent high cut-off potentials during cell cycling are compatible with commercially used carbonate-based electrolytes and graphite anodes, or if unfavorable interactions among them exist and thus lead to the poor performance of some DRX materials . In this study, a DRX material with a stoichiometry of Li 1.25 Fe 0.5 Nb 0.25 O 2 , which was previously reported to suffer from strong capacity fading and involve substantial amounts of anionic redox activity, was used to investigate the compatibility of the DRX material with a conventional organic carbonate-based electrolyte. For comparison, this material was also studied in an ionic liquid (IL)-based electrolyte, which was used because of its presumed superior stability against oxidation and high potentials. − The surface of the cycled electrodes in these two electrolytes was thoroughly characterized, and thus, information regarding the mechanism of cathode electrolyte interphase (CEI) formation and electrode degradation in conventional carbonate-based electrolytes is obtained.…”

“…Research focus so far has been on the understanding of these intricate redox processes and the factors influencing them. 21 Little attention has been paid to the interactions between DRX materials and other components of a battery cell, for example, the electrolyte, the anode, and so on. It is still unclear if the relatively high potentials of the anionic redox displayed by these materials and the consequent high cut-off potentials during cell cycling are compatible with commercially used carbonate-based electrolytes and graphite anodes, or if unfavorable interactions among them exist and thus lead to the poor performance of some DRX materials.…”

Pillar-beam structures prevent layered cathode materials from destructive phase transitions

“…Meanwhile, a small amount of CO 2 gas was released. We believe it was generated by the decomposition of traces of Na 2 CO 3 in the electrode and the side reactions involving the electrolyte at high voltage 40 – 42 . To conclude, based on these results that the charge transfer during the cell operation led to valence changes of the transition metal ions only, and oxygen ions did not participate in the electrochemical reaction, hence no gas evolution reactions occurred.…”