In-Situ X-ray Absorption Spectroscopy of Ti-Modified NaNiO2 Cathodes for Sodium-Ion Batteries

Sodium-ion batteries are attracting much attention for electrochemical energy-storage applications due to the higher abundance and lower cost of sodium compared with lithium. Layered transition-metal oxides, in particular NaNiO2 (NNO), hold promise as high-capacity cathode active materials. However, they typically suffer from capacity degradation during battery operation. To address this issue, NaNi0.9Ti0.1O2 (NNTO) has been successfully synthesized and found to exhibit significantly improved cycling performance and stability over NNO. This is due in part to benefits of having two active redox couples, namely Ni2+/Ni3+ and Ni3+/Ni4+, in NNTO. To correlate the redox chemistry with the electrochemical behavior and to gain insights into the electronic and local structural environments of nickel and titanium, we plan to perform in-situ XAS measurements at the Ni and Ti K-edges.