My name is Juan Andrés Nieto Simón and I am hired as Research Support Staff in the research group Preparation, Characterization and Properties of Non-Molecular Solids in the Department of Inorganic Chemistry at the Faculty of Chemical Sciences of the Complutense University of Madrid. My research line focuses on the development of electrodes for rechargeable potassium-ion batteries (KIBs) based on hollandite-type materials. The synthesis of these materials is carried out by means of a sol-gel soft chemistry procedure called "citrate method". The structural characterisation comprises techniques such as: powder X-ray diffraction, X-ray fluorescence, scanning and transmission electron microscopy, etc. Electrochemical characterisation is carried out by galvanostatic charge-discharge measurements. The study of these functional materials is aimed at solving scientific or technological problems demanded by today's society.