Doubling the cyclic stability of 3D hierarchically structured composites of 1T-MoS2/polyaniline/graphene through the formation of LiF-rich solid electrolyte interphase

MoS2 has been viewed as a unique anode material for lithium-ion batteries; however, its electrochemical performance is usually restrained by poor conductivity of 2H phase and an uneven solid-electrolyte interphase (SEI). To tackle the above issues, the ternary composite is synthesized by self-assembling MoS2 2D sheets with higher percentage of metallic 1T-phase on polyaniline functionalized reduced graphene oxide (PANI-rGO) through an electrostatic interaction. The flower-like aggregate of 1T-MoS2 having increased interlayer distances is beneficial for diffusion and intercalation of lithium ions. Furthermore, the graphene substrate facilitates the electron transportation. At the current density of 0.1 and 2 A g-1, the ternary composite has the specific capacities of 812 and 333 mAh g-1 respectively. On the other hand, the cyclic stability of ternary composite can be further improved when 10 wt% fluoroethylene carbonate (FEC) is added into the traditional carbonate-based electrolyte. The capacity retention of ternary composite cycled in a FEC-mixed electrolyte is two times higher than that in a traditional electrolyte after 400 charge-discharge cycles. This is attributed to the fact that the use of FEC enables the formation of active LiF-rich SEI.

Automated summary

The ternary composite of MoS2, PANI-rGO, and FEC shows enhanced lithium-ion diffusion and intercalation, as well as improved electron transportation. The addition of 10 wt% FEC into the traditional electrolyte significantly enhances the cyclic stability of the ternary composite, leading to two times higher capacity retention after 400 charge-discharge cycles.