Large-Scale Synthesis of High Energy Thermal Battery Cathode Ni_0.5Co_0.5S₂ by a Simple Sintering Technique

With the synergies of multiple elements, bimetallic sulfides exhibit excellent performance as splendid electrode materials and effective catalysts. However, large-scale synthesis of high-performance single-phase multicomponent sulfides has always been a challenge. Based on thermodynamic calculations, the intermediate phases NiS 2 and Co 3 S 4 are devoted to the synthesis of single-phase Ni 0.5 Co 0.5 S 2 . Because the reaction from NiS 2 and Co 3 S 4 to Ni 0.5 Co 0.5 S 2 goes through a lower energy, it thermodynamically contributes to achieving a single-phase structure. Thus, single-phase Ni 0.5 Co 0.5 S 2 can be simply and quickly prepared by two-step sintering and successfully scalable for mass production. This technique can extend to the whole ingredients Ni 1– x Co x S 2 . Ni 0.5 Co 0.5 S 2 demonstrates excellent thermal stability and good conductivity. It delivers a specific capacity of 671 mAh·g –1 and a specific energy of 1173 Wh·kg –1 when applied to a thermal battery cathode, which are increased by 18.6% and 25.0%, respectively, compared to pristine NiS 2 (566 mAh·g –1 ) and CoS 2 (537 mAh·g –1 ). This work proposes an innovative sintering method, which is applicable for cost-efficient and large-scale synthesis of single-phase multicomponent sulfides.