Carbon coating and phase engineering (1T phase and 1T/2H mixed phase) can improve electron transfer owing to the presence of carbon and the metallic nature of the 1T phase (10-100 S cm -1 ), respectively. Structural stability can be strengthened by expanding interlayer spacing and tuning the morphology and/or dimensionality of MoS2 to relieve the strain in vertical and radial directions during K-ion insertion. While progress has been made to driving the PIB performance development of MoS2, understanding of the electrochemical mechanism to store K-ions has not been progressed to the same extent as performance development, due to the complexity in phase transition and kinetic processes involved in electrochemical K storage in MoS2. Understanding the mechanism is crucial to guide the structural and phase engineering of MoS2 and even intrigue new design strategies.