Fabrication of Na0.7MnO2/C composite cathode material by simple heat treatment for high-power na-ion batteries

• Published in: Electronic materials letters 2018, 14(1), , pp.30-36
• Main Authors: Sohn, DongRak, Lim, Sung-Jin, Nam, Do-Hwan, Hong, Kyung-Sik, Kim, Tae-Hee, Oh, SeKwon, Eom, Ji-Yong, Cho, EunAe, Kwon, HyukSang
• Format: Article
• Language: English
• Subjects: Cathodes; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry and Materials Science; Condensed Matter Physics; Discharge; Electrode materials; Heat treatment; Materials Science; Nanotechnology; Nanotechnology and Microengineering; Optical and Electronic Materials; Particulate composites; Rechargeable batteries; Sodium-ion batteries; X ray photoelectron spectroscopy; 전자/정보통신공학
• ISSN: 1738-8090; 2093-6788
• DOI: 10.1007/s13391-017-7085-6

A Na 0.7 MnO 2 /C composite cathode material is synthesized by simple and costeffective two-step heat treatment for an improvement in the rate capability of Na 0.7 MnO 2 . The first heat treatment is to synthesize Na 0.7 MnO 2 , and the second one is a low temperature annealing at 350 °C for 1 h in air, which is necessary to suppress an interfacial reaction between the Na 0.7 MnO 2 and C in the synthesis process of Na 0.7 MnO 2 /C composite. Structural analyses by XRD and XPS reveal that the Na 0.7 MnO 2 /C shows the same structural properties as that of the pristine Na 0.7 MnO 2 , and hence they exhibit the same initial discharge capacity of 175 mAh g −1 at 20 mA g −1 . At a current density of 400 mA g −1 , the discharge capacity of Na 0.7 MnO 2 reduces to 50 mAh g −1 (28% of the initial discharge capacity), whereas that of Na 0.7 MnO 2 /C reduces to 108 mAh g −1 (61% of the initial discharge capacity). The enhanced rate capability of the Na 0.7 MnO 2 /C is attributed to the conductive carbon layer formed on the surface of Na 0.7 MnO 2 particles, enabling the facile transport of electrons from the current collector to the surface of the Na 0.7 MnO 2 particles.