Lithium (Li) ion batteries is the most common battery technology but lately also potassium (K) batteries are being considered. One reason is that the Li-reserves are limited and if with increasing use of electric vehicles, we might have to reconsider the Li-ion technology. From a material point of view, K is heavier than Li, hence, K-ion batteries are assumed to be bulkier and more suitable for stationary applications e.g. energy storage from solar panels and wind turbines. However, K has also many advantages over Li. K is e.g. one of the most abundant elements in nature, which makes them >10 times cheaper than Li. Further, K-batteries are further though to be better from a safety and environment/health point of view. In this research project we will study a series of new series of recently discovered K-ion battery materials that initially have shown very promising performance.