Study on modification and electrochemical properties of COS2-based cathode materials†

Abstract

Thermal batteries are widely used in defense and emergency fields due to their long storage periods and high power characteristics. Among them, cobalt disulfide (CoS₂), as a cathode material, attracts attention because of its high decomposition temperature, excellent discharge capacity, and good electrical conductivity. However, research has found that this material is prone to structural decomposition and phase transition under high-temperature working conditions and long-term storage, leading to critical issues such as electrode activity decay and battery performance degradation. This study innovatively adopts atomic layer deposition (ALD) technology to construct a nanoscale Al₂O₃ coating on the CoS₂ surface, and systematically analyzes it through multi-dimensional characterization methods such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). Experimental results show that after an 8 days simulated storage test, the discharge specific capacity of unmodified CoS₂ decreased to 70% of its initial value, while the Al₂O₃/CoS₂ composite material maintained a capacity retention rate of 90%. This study confirms that Al₂O₃ surface modification technology can effectively inhibit the structural degradation of CoS₂, significantly enhancing the material's environmental tolerance and electrochemical stability.