The number of studies of rechargeable current sources with potassium and its compounds, such as potassium-ion batteries, potassium-chalcogen (sulfur, selenium) and potassium-oxygen (air) based batteries, has been growing since 2015 and in 2020, it exceeded 350 papers in total. This mini review continues a series of our publications about the development of the studies in the field of rechargeable systems based on alkaline metals and magnesium and considers only the papers published in 2020. As before, due to abundant experimental researches, we primarily considered the reviews and only a few of original w orks. Creation of lithium-ion batteries, their mass production (in 2021, it is the 30th anniversary since the launch of their production) became one of the greatest successes of the modern applied electrochemistry. In 2019, the authors of the pioneering works in this field were awarded the Nobel prize. Nonetheless, because of various requirements to autonomous electric sources (electrochemical parameters, accessibility and cost of materials for their manufacturing, operational safety, etc.), there is a never ending and intent search for new electrode materials and electrolytes for Li-ion batteries, and new electrochemical systems which could compete with the lithium batteries. Modern conferences on current sources provide a separate section: “Beyond Li-ion”.