Synthesis of rock salt Pb_1-xSr_xTe with unusual stabilized compositions and their electrochemical performance

The cubic crystal structure Pb_1-xSr_xTe polyhedral microcrystals with unusual stabilized compositions were synthesized using a facile solvothermal approach through balancing chemical reactivity of metal complex precursor and Te precursor. The presence of EDTA plays a crucial role in the formation of pure phase polyhedrons, avoiding the formation of SrCO₃ impurity. The various reaction kinetic experimental parameters, including proper metal complex precursors, mixed solvent ratios, the appropriate temperature, and the amount of KOH, were able to control the morphology of Pb_0.95Sr_0.05Te and achieve much higher level of Sr alloyed into the PbTe matrix (5.2–6.5 mol% SrTe/PbTe), which is beyond its thermodynamic solubility limit of 1 mol% in bulk. Furthermore, these materials were successfully used as the electrodes of lithium ion batteries, possessing better cycling stability and the improved rate capability compared to pristine PbTe. We envision that the established strategy is general and robust, and offers easy access to other ternary PbTe-based alloy materials through careful balancing precursor chemical reactivity.