•  
  •  
 
Nano Research

Article Title

NaF–FeF2 nanocomposite: New type of Na-ion battery cathode material

Authors

Insang Hwang, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea
Sung-Kyun Jung, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea
Eun-Suk Jeong, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea
Hyunchul Kim, Department of Energy Science (DOES), Sungkyunkwan University, Suwon 16419, Republic of Korea
Sung-Pyo Cho, National Center for Inter-University Research Facilities, Seoul National University, Seoul 08826, Republic of Korea
Kyojin Ku, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea
Hyungsub Kim, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea Neutron Science Division, HANARO, Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea
Won-Sub Yoon, Department of Energy Science (DOES), Sungkyunkwan University, Suwon 16419, Republic of Korea
Kisuk Kang, Department of Materials Science and Engineering, Research Institute of Advanced Materials (RIAM), Seoul National University, Seoul 08826, Republic of Korea Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul National University, Seoul 08826, Republic of Korea

Keywords

nanocomposite, Na-ion batteries, NaF, FeF2, cathode

Abstract

ABSTRACT Na-ion batteries (NIBs) are considered one of the most attractive alternatives for Li-ion batteries (LIBs) because of the natural abundance of Na and the similarities between the NIB technology and the well-established LIB technology. However, the discovery of high-performance electrode materials remains a key factor in the success of NIBs. Herein, we propose a new type of cathode material for NIBs based on a nanocomposite of an alkali metal fluoride (NaF) and a transition metal fluoride (FeF2). Although neither of these components is electrochemically active with Na, the nanoscale mixture of the two can deliver a reversible capacity of ~125 mAh/g in the voltage range of 1.2–4.8 V vs. Na/Na+ via an Fe2+/Fe3+ redox couple. X-ray absorption spectroscopy reveals that the reversible Na storage is aided by the F– ions due to the decomposition of NaF, which are absorbed on the surface of FeF2, promoting the redox reaction of Fe and triggering the gradual transformation of the mother structure (FeF2) into a new (FeF3-like) host structure for the Na ions. This unique Na-ion storage phenomenon, which is reported for the first time, will introduce an avenue for designing novel cathode materials for NIBs.

Graphical Abstract

Publisher

Tsinghua University Press

Share

COinS