Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi2TeO6
Titus Masese, Yoshinobu Miyazaki, Josef Rizell, Godwill Mbiti Kanyolo, Chih-Yao Chen, Hiroki Ubukata, Keigo Kubota, Kartik Sau, Tamio Ikeshoji, Zhen‐Dong Huang, Kazuki Yoshii, Terüo Takahashi, Miyu Ito, Hiroshi Senoh, Jinkwang Hwang, Abbas Alshehabi, Kazuhiko Matsumoto, Toshiyuki Matsunaga, Kotaro Fujii, Masatomo Yashima, Masahiro Shikano, Cédric Tassel, Hiroshi Kageyama, Yoshiharu Uchimoto, Rika Hagiwara, Tomohiro Saito
Abstract
Abstract Honeycomb layered oxides constitute an emerging class of materials that show interesting physicochemical and electrochemical properties. However, the development of these materials is still limited. Here, we report the combined use of alkali atoms (Na and K) to produce a mixed-alkali honeycomb layered oxide material, namely, NaKNi 2 TeO 6 . Via transmission electron microscopy measurements, we reveal the local atomic structural disorders characterised by aperiodic stacking and incoherency in the alternating arrangement of Na and K atoms. We also investigate the possibility of mixed electrochemical transport and storage of Na + and K + ions in NaKNi 2 TeO 6 . In particular, we report an average discharge cell voltage of about 4 V and a specific capacity of around 80 mAh g –1 at low specific currents (i.e., < 10 mA g –1 ) when a NaKNi 2 TeO 6 -based positive electrode is combined with a room-temperature NaK liquid alloy negative electrode using an ionic liquid-based electrolyte solution. These results represent a step towards the use of tailored cathode active materials for “dendrite-free” electrochemical energy storage systems exploiting room-temperature liquid alkali metal alloy materials.