Enhancing the electrochemical performance of an O3–NaCrO2 cathode in sodium-ion batteries by cation substitution

• Published in: Journal of power sources Vol. 435; p. 226760
• Main Authors: Wang, Yuesheng, Cui, Peixin, Zhu, Wen, Feng, Zimin, Vigeant, Marie-Josée, Demers, Hendrix, Guerfi, Abdelbast, Zaghib, Karim
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.09.2019
• Subjects: Cathode; DFT; In-situ XRD; NaCrO2; Sodium ion batteries; XAS; Sodium ion batteries; DFT; XAS; NaCrO2; In-situ XRD; Cathode
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.226760

O3/P2-layered oxides, especially O3–NaCrO2, have been widely investigated as cathode materials for sodium-ion batteries due to their high stability and flexible synthesis procedure, but their low electron conductivity, the toxicity of Cr(VI) and cation disorder limit their applications. Here, we present O3–Na(Cr0.8Mn0.2)O2 as a promising cathode, which has a higher average storage voltage than O3–NaCrO2 and a practical useable capacity of ca. 100 mAh/g. The low volume change (~0.90%), lack of toxic Cr6+ formation and cation ordering in the optimized O3–Na(Cr,Mn)O2 structure ensure a potentially long cycle life. In situ XRD was used to monitor the phase formation at high temperature and to unveil the working mechanism of the O3–Na(Cr,Mn)O2 electrode during cycling. XAS and DFT investigations revealed variations in the local structure and the sequence of charge transfer of the transition metal during cycling. This work sheds light on the sodium storage mechanism of O3-layered oxides from micro- and electronic-structure points of view and reveals the role of transition metals in the working mechanism and performance. [Display omitted] •The low volume change of NaCr0.8Mn0.2O2 ensures a potentially long cycle life.•In-situ high temperature XRD monitors the phase formation at providing optimum conditions.•XAS results revealed the oxidation states of Mn and Cr in the electrochemical process.