Heterostructure-promoted rate performance of CoS2 in thermal activated batteries

CoS2 cathode has been extensively adopted for application in thermal batteries due to its excellent electrochemical performance. However, CoS2 undergoes rapid discharge degradation at high-rates or low working temperatures because of its high polarization resistance. This is ascribed to the kinetically slow rate of Li+ inset in the CoS2 cathode. With the aim of accelerating charge carrier exchange at the cathode-electrolyte interface, the construction of a heterostructure with an engineered electronic structure at the surface of CoS2 is described in this present work. The results show that the specific discharge capacity (V ≥ 1.75 V) of heterostructured CoS2 increases 23% at 500 °C and 42.3% at 450 °C with discharge currents of 300 and 100 mA cm−2, respectively. Electrochemistry measurements and density functional theory (DFT) analysis decipher that N modification alters the surface structure of CoS2, resulting in beneficial “defect” formation, that further enhances surface exchange density and the adsorption capability of Li+.