High capacity Co0.8Fe0.2S2 thermal battery cathode prepared by a solid-state synthesis technique

CoS₂ with high thermal stability is commonly used as cathode material for thermal batteries, however, its practical performance is limited by insufficient electrochemical reactions during discharge. Enlighted by metal-doping that can regulate the electronic environment and lattice structure, high-energy Co_0.8Fe_0.2S₂ is successfully prepared by solid-state methods. Remarkably, with a current density of 0.3 A·cm⁻² at a cutoff voltage of 1.42 V under 550 °C, Co_0.8Fe_0.2S₂ exhibits excellent performance with a prolonged discharge platform and decreased resistance (0.23 Ω), generating an ultrahigh specific capacity of 652 mAh·g⁻¹_, which is 31 % higher than that of pure CoS₂. Our research indicates that Co_0.8Fe_0.2S₂ is suitable for high-energy and high-temperature thermal batteries. The feasibility of solid-state synthesis of pure-phase bimetallic disulfides has been verified as well, paving the way for industrial application of Co_0.8Fe_0.2S₂.