2, Kyoto University, Kyoto, , Japan
We have been studying electrode and electrolyte materials for Li-ion batteries. In the past 15 years, we have also studied the materials for Na-ion batteries [1,2]. As we described in the papers, yearly paper numbers of Na batteries have increased drastically in 2010s. Indeed, research and development of high-performance positive/negative electrode materials for Na-ion are conducted actively. Because of larger ionic size of sodium than lithium, much wider variety of materials chemistry attracts researchers’ interests as post Li-ion battery.
From 2013, we began to expand our research target to K-ion batteries, which is potentially expected to demonstrate higher-power and higher-voltage than Li-ion batteries, in spite of heavier and larger potassium atoms . We study a variet of potassium insertion materials based on our experience of lithium and sodium ones, and their electrochemistry is examined and compared in corresponding non-aqueous electrolytes. We will talk about and introduce our recent progress on alkali-metal insertion materials for Na-ion and K-ion batteries and will discuss similarity and difference compared with Li-ion ones.
 N. Yabuuchi, S. Komaba, et al., Chem. Rev., 114, 11636 (2014).
 K. Kubota, S. Komaba et al., J. Electrochem. Soc., 162, A2538 (2015).
 X. Bie, S. Komaba et al, J. Mater. Chem. A, 5, 4325 (2017).