Role of the voltage window on the capacity retention of P2-Na2/3[Fe1/2Mn1/2]O2 cathode material for rechargeable sodium-ion batteries

Maider Zarrabeitia; Francesco Nobili; Oier Lakuntza; Javier Carrasco; Teófilo Rojo; Montse Casas-Cabanas; Miguel Ángel Muñoz-Márquez

doi:10.1038/s42004-022-00628-0

Role of the voltage window on the capacity retention of P2-Na_2/3[Fe_1/2Mn_1/2]O₂ cathode material for rechargeable sodium-ion batteries

Commun Chem. 2022 Feb 1;5(1):11. doi: 10.1038/s42004-022-00628-0.

Authors

Maider Zarrabeitia^{1

2

3}, Francesco Nobili⁴, Oier Lakuntza¹, Javier Carrasco¹, Teófilo Rojo^{1

5}, Montse Casas-Cabanas^{1

6}, Miguel Ángel Muñoz-Márquez^{7

8}

Affiliations

¹ Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510, Vitoria-Gasteiz, Spain.
² Helmholtz Institute Ulm (HIU), Helmholtzstrasse 11, 89081, Ulm, Germany.
³ Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021, Karlsruhe, Germany.
⁴ School of Science and Technology-Chemistry Division, University of Camerino, Via Madonna delle Carceri, 62032, Camerino, Italy.
⁵ Departamento de Química Inorgánica, Universidad del País Vasco UPV/EHU, P.O. Box 664, 48080, Leioa, Spain.
⁶ IKERBASQUE, Basque Foundation for Science, María Díaz de Haro 3, 48013, Bilbao, Spain.
⁷ Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, 01510, Vitoria-Gasteiz, Spain. miguel.munoz@unicam.it.
⁸ School of Science and Technology-Chemistry Division, University of Camerino, Via Madonna delle Carceri, 62032, Camerino, Italy. miguel.munoz@unicam.it.

Abstract

P2-Na_2/3[Fe_1/2Mn_1/2]O₂ layered oxide is a promising high energy density cathode material for sodium-ion batteries. However, one of its drawbacks is the poor long-term stability in the operating voltage window of 1.5-4.25 V vs Na⁺/Na that prevents its commercialization. In this work, additional light is shed on the origin of capacity fading, which has been analyzed using a combination of experimental techniques and theoretical methods. Electrochemical impedance spectroscopy has been performed on P2-Na_2/3[Fe_1/2Mn_1/2]O₂ half-cells operating in two different working voltage windows, one allowing and one preventing the high voltage phase transition occurring in P2-Na_2/3[Fe_1/2Mn_1/2]O₂ above 4.0 V vs Na⁺/Na; so as to unveil the transport properties at different states of charge and correlate them with the existing phases in P2-Na_2/3[Fe_1/2Mn_1/2]O₂. Supporting X-ray photoelectron spectroscopy experiments to elucidate the surface properties along with theoretical calculations have concluded that the formed electrode-electrolyte interphase is very thin and stable, mainly composed by inorganic species, and reveal that the structural phase transition at high voltage from P2- to "Z"/OP4-oxygen stacking is associated with a drastic increased in the bulk electronic resistance of P2-Na_2/3[Fe_1/2Mn_1/2]O₂ electrodes which is one of the causes of the observed capacity fading.