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High voltage mg-doped Na0.67Ni0.3–xMgxMn0.7O2 (x = 0.05, 0.1) Na- ion cathodes with enhanced stability and rate capability

DOI: 10.1021/acs.chemmater.6b01935 DOI Help

Authors: Gurpreet Singh (CICenergigune) , Nuria Tapia-Ruiz (University of Oxford) , Juan Miguel Lopez Del Amo (CICenergigune) , Urmimala Maitra (University of Oxford) , James W. Somerville (University of Oxford) , A. Robert Armstrong (University of St. Andrews) , Jaione Martinez De Ilarduya (CICenergigune) , Teófilo Rojo (CICenergigune; Universidad del País Vasco) , Peter Bruce (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials , VOL 28 , PAGES 5087 - 5094

State: Published (Approved)
Published: July 2016

Open Access Open Access

Abstract: Magnesium substituted P2-structure Na0.67Ni0.3Mn0.7O2 materials have been prepared by a facile solid-state method and investigated as cathodes in sodium-ion batteries. The Mg-doped materials described here were characterized by X-ray diffraction (XRD), 23Na solid-state nuclear magnetic resonance (SS-NMR), and scanning electron microscopy (SEM). The electrochemical performance of the samples was tested in half cells vs Na metal at room temperature. The Mg-doped materials operate at a high average voltage of ca. 3.3 V vs Na/Na+ delivering specific capacities of ∼120 mAh g–1, which remain stable up to 50 cycles. Mg doping suppresses the well-known P2–O2 phase transition observed in the undoped composition by stabilizing the reversible OP4 phase during charging (during Na removal). GITT measurements showed that the Na-ion mobility is improved by 2 orders of magnitude with respect to the parent P2–Na0.67Ni0.3Mn0.7O2 material. The fast Na-ion mobility may be the cause of the enhanced rate performance.

Journal Keywords: Chemical structure; Physical and chemical processes; Transition metals; Phase transitions; Materials

Diamond Keywords: Batteries; Sodium-ion

Subject Areas: Materials, Chemistry, Energy

Instruments: B18-Core EXAFS

Added On: 11/11/2016 15:41


Discipline Tags:

Energy Storage Energy Physical Chemistry Energy Materials Chemistry Materials Science Chemical Engineering Engineering & Technology

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS)