Structural and electrochemical analysis of Zn doped Na3Ni2SbO6 cathode for Na-ion battery

• Published in: Journal of power sources 2016-12, Vol.336, p.186-195
• Main Authors: Aguesse, Frederic, Lopez del Amo, Juan-Miguel, Otaegui, Laida, Goikolea, Eider, Rojo, Teofilo, Singh, Gurpreet
• Format: Article
• Language: English
• Subjects: Cathode; Layered oxides; Na-ion battery; Smooth voltage profile; Zn substitution
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2016.10.067

The effect of Zn2+ substitution on the electrochemical performance and the structural evolution upon cycling of Na3Ni2SbO6 and Na3Zn0.5Ni1.5SbO6 is reported. Samples were synthesized by solid state route and characterised by ex-situ X-ray diffraction and ex-situ23Na solid state NMR, the results show that the partial substitution of Ni2+ by Zn2+ alters the superstructure symmetry and leads to a disordered lattice. This structural reorganisation has direct consequences on the electrochemical performances of Na3Zn0.5Ni1.5SbO6 with an average voltage of ∼3.3 V and with a specific capacity increase up to 145 mAh.g−1 at C/10. We observe that Zn2+ cations are inhomogeneously distributed in the structure, leading to different Na+ environments which are characterized by NMR. The phase transitions observed at high voltage in Na3Ni2SbO6 are suppressed in Na3Ni1.5Zn0.5SbO6 resulting in a smooth electrochemical profile with a low polarization. The presence of an irreversible phase at the end of the discharge was also detected in the undoped material. •Influence of Zn-doping on electrochemical performances of Na3Ni2SbO6 layered oxide.•Ex-situ XRD and NMR to follow the structural evolution of Na-based cathode.•Superstructural disordering by partial substitution of Ni2+ by Zn2+ in Na3Ni2SbO6.•Higher operating voltage than those corresponding layer oxides.•Smoothening of the electrochemical profile by Zn-substitution.