MoS2 Additives in Lithium Grease for Electrified Systems

This study investigates the effectiveness of micron- and nano-sized molybdenum disulfide (MoS2) particles as additives in lithium (Li) grease under electrified conditions. By systematically applying electric current and high temperatures as experimental parameters, we evaluated the frictional and wear performance of the grease formulations. Our results showed that micron MoS2 (M-MoS2) particles outperform their nano counterparts in reducing friction in the range of room temperature to 40 °C. Meanwhile, at 80 °C, nano-sized MoS2 (N-MoS2) particles provide better surface protection. The superior performance of M-MoS2 is attributed to their particle size, which improves the ability to form a more stable and robust lubricating film under the given electrical conditions. In terms of wear, both MoS2-added greases showed substantial improvements, with a 93% reduction in wear at 40 °C and an 85% at 80 °C under an applied 3 A current. Surface characterization revealed that M-MoS2 resulted in a smoother surface with less severe pitting and melted pools compared to the base grease. EDX analysis showed the existence of oxygen, molybdenum, and sulfur in M-MoS2, indicating the presence and stability of MoS2 on the wear track. These findings suggest that MoS2 additives have great potential for improving the efficiency and durability of lubricants in electrically and thermally demanding applications.