Stabilization of O-O Bonds by d 0 Cations in Li 4+ x Ni 1- x WO 6 (0 ≤ x ≤ 0.25) Rock Salt Oxides as the Origin of Large Voltage Hysteresis.

Autor: Taylor ZN, Perez AJ, Coca-Clemente JA; Stephenson Institute for Renewable Energy , University of Liverpool , Chadwick Building, Peach Street , Liverpool L69 7ZF , United Kingdom., Braga F; Stephenson Institute for Renewable Energy , University of Liverpool , Chadwick Building, Peach Street , Liverpool L69 7ZF , United Kingdom., Drewett NE; Stephenson Institute for Renewable Energy , University of Liverpool , Chadwick Building, Peach Street , Liverpool L69 7ZF , United Kingdom., Pitcher MJ, Thomas WJ, Dyer MS, Collins C, Zanella M, Johnson T, Day S; Diamond Light Source , Diamond House , Harwell Oxford, Didcot , Oxfordshire OX11 0DE , United Kingdom., Tang C; Diamond Light Source , Diamond House , Harwell Oxford, Didcot , Oxfordshire OX11 0DE , United Kingdom., Dhanak VR; Stephenson Institute for Renewable Energy , University of Liverpool , Chadwick Building, Peach Street , Liverpool L69 7ZF , United Kingdom., Claridge JB, Hardwick LJ; Stephenson Institute for Renewable Energy , University of Liverpool , Chadwick Building, Peach Street , Liverpool L69 7ZF , United Kingdom., Rosseinsky MJ
Jazyk: angličtina
Zdroj: Journal of the American Chemical Society [J Am Chem Soc] 2019 May 08; Vol. 141 (18), pp. 7333-7346. Date of Electronic Publication: 2019 Apr 24.
DOI: 10.1021/jacs.8b13633
Abstrakt: Multinary lithium oxides with the rock salt structure are of technological importance as cathode materials in rechargeable lithium ion batteries. Current state-of-the-art cathodes such as LiNi 1/3 Mn 1/3 Co 1/3 O 2 rely on redox cycling of earth-abundant transition-metal cations to provide charge capacity. Recently, the possibility of using the oxide anion as a redox center in Li-rich rock salt oxides has been established as a new paradigm in the design of cathode materials with enhanced capacities (>200 mAh/g). To increase the lithium content and access electrons from oxygen-derived states, these materials typically require transition metals in high oxidation states, which can be easily achieved using d 0 cations. However, Li-rich rock salt oxides with high valent d 0 cations such as Nb 5+ and Mo 6+ show strikingly high voltage hysteresis between charge and discharge, the origin of which is uninvestigated. In this work, we study a series of Li-rich compounds, Li 4+ x Ni 1- x WO 6 (0 ≤ x ≤ 0.25) adopting two new and distinct cation-ordered variants of the rock salt structure. The Li 4.15 Ni 0.85 WO 6 (x = 0.15) phase has a large reversible capacity of 200 mAh/g, without accessing the Ni 3+ /Ni 4+ redox couple, implying that more than two-thirds of the capacity is due to anionic redox, with good cyclability. The presence of the 5d 0 W 6+ cation affords extensive (>2 V) voltage hysteresis associated with the anionic redox. We present experimental evidence for the formation of strongly stabilized localized O-O single bonds that explain the energy penalty required to reduce the material upon discharge. The high valent d 0 cation associates localized anion-anion bonding with the anion redox capacity.
Databáze: MEDLINE