Abstract: The invention relates to a crystalline ion-conducting material made of LiMPO4 nanoparticles, wherein M is selected from Cr, Mn, Co, Fe and Ni, in addition to mixtures thereof and the nanoparticles have an essentially flat prismatic shape. The invention also relates to a method for producing said type of crystalline ion-conducting material which consists of the following steps: a precursor component is produced in a solution front a lithium compound of a component containing metal ions M and a phosphate compound, the precursor compound is subsequently precipitated from the solution and, optionally, a suspension of the precursor compound is formed, the precursor compound and/or the suspension is dispersed and/or ground, and the precursor compound and/or the suspension is converted under hydrothermal conditions and subsequently, the crystalline material is extracted.