First-Principles Screening and Evaluation of Sulfide Compounds for Multivalent Battery Cathode Applications

The rapid growth of portable consumer electronics and electric vehicles demands new battery technologies with greater energy stored at a reduced cost. Energy storage solutions based on multivalent metals, such as Mg, could significantly increase the energy density as compared to lithium-ion based technology. In this work, we use recent advances in high-throughput first-principles calculations to systematically evaluate the performance of a group of 3 d transition-metal sulfide compounds for multivalent cathode applications. We estimate the insertion voltage, capacity, thermodynamic stability of charged and discharged states, as well as the intercalating ion mobility and use these properties to evaluate promising directions. From our calculations, we identified sulfide compounds that exhibit improved Mg 2+ mobility with feasible low diffusion activation energy; lower than their oxide counterparts, however the improved mobility comes at the expense of lower voltage and thereby lower theoretical specific energy. We also identified a Ca 2+ intercalating sulfide compound which exhibits a low diffusion activation barrier of ~500 meV and a voltage of ~2V, revealing a potential cathode for use in Ca ion rechargeable batteries. We also present several general trends and design insights extracted from our evaluation for this category of materials.