Rational design of MWCNTs@amorphous carbon@MoS2: Towards high performance cathode for aqueous zinc-ion batteries

The sluggish diffusion kinetics of divalent Zn2+ in cathode and the limited availability of active material have seriously hindered the practical application of aqueous zinc ion batteries (AZIBs). Herein, multi-walled carbon nanotubes modified by amorphous carbon layer successfully compounded with MoS2 (MWCNTs@a-C@MoS2) are designed as the cathode for AZIBs. Benefiting from the large number of oxygenous groups on the loose surface of amorphous carbon, MoS2 can uniformly nucleate and grow on the MWCNTs, thus avoiding the agglomeration of MoS2 and improving the utilization of active materials. Therefore, this nanocomposite exhibits long-term cycling stability (78% capacity retention after 1000 cycles at 5 A g-1) and glorious high-rate capability (110 mAh g-1 at 12 A g-1). The electrochemical reaction kinetics of MWCNTs@a-C@MoS2 electrode were investigated by galvanostatic intermittent titration (GITT), cyclic voltammetry (CV) measurements and molecular dynamics (MD) simulations, indicating its desirable pseudocapacitive behaviors and low Zn2+ diffusion energy barrier. By ex-situ characterizations, the Zn-intercalation mechanism of MWCNTs@a-C@MoS2 was revealed. This electrode also exhibits stable performance in flexible quasi-solid-state AZIBs even under extreme bending conditions, demonstrating its practicality.