We have been studing electrode and electrolyte materials for Li-ion batteries.  In the past 10 years, we have also studied the materials for Na-ion batteries.  Indeed we succeeded high-capacity or high-energy positive / negative electrode materials including binders and electrolytes.  Recently, we expand our research target to K-ion batteries, which is potentially expected to show higher-power and higher-voltage than those of Li- and Na-ion batteries.  We will talk about our recent achievement on electrode and electrolyte materials and surface chemistry for Na-ion and K-ion batteries and will discuss similarity and difference compared with Li-ion ones.