Development of High Capacity Cathode Material for Sodium Ion Batteries Na0.95Li0.15(Ni0.15Mn0.55Co0.1)O2

• Published in: Journal of the Electrochemical Society Vol. 160; no. 6; pp. A933 - A939
• Main Authors: Kataoka, Riki, Mukai, Takashi, Yoshizawa, Akihiro, Sakai, Tetsuo
• Format: Journal Article
• Language: English; Japanese
• Published: The Electrochemical Society 2013
• ISSN: 0013-4651
• DOI: 10.1149/2.125306jes

A high-capacity layered metal oxide material, Na0.95Li0.15(Mn0.55Co0.10Ni0.15)O2, was obtained by the electrochemical Li-Na ion-exchange of Li1.2Mn0.55Co0.10Ni0.15O2. The electrochemical reaction of the Na0.95Li0.15(MnCoNi)0.8O2 was divided into three redox reactions, i.e., Mn, Ni and Co. The Na0.95Li0.15(MnCoNi)0.8O2 electrode showed good electrochemical properties in a sodium ion cell, such as a high capacity of over 200 mAhg−1 and its 40th discharge capacity was 170 mAhg−1 which is about 85% of the 2nd discharge capacity. An ex-situ synchrotron X-ray diffraction analysis revealed that the Na0.95Li0.15(Mn0.55Co0.10Ni0.15)O2 maintains the O3-type layered structure with a large volume change of 20% during the charge-discharge cycles along with the formation of a secondary phase which has the same crystal structure as that of the Na0.95Li0.15(Mn0.55Co0.10Ni0.15)O2 in the high voltage range. When the open circuit voltage of the Na0.95Li0.15(Mn0.55Co0.10Ni0.15)O2 reached 4.2 V, the secondary phase was present as a single phase.