Scaly MoS/rGO Composite as an Anode Material for High-Performance Potassium-Ion Battery.

Potassium-ion batteries (PIBs) have been widely studied owing to the abundant reserves, widespread distribution, and easy extraction of potassium (K) resources. Molybdenum disulfide (MoS) has received a great deal of attention as a key anode material for PIBs owing to its two-dimensional diffusion channels for K ions. However, due to its poor electronic conductivity and the huge influence of embedded K ions (with a large ionic radius of 3.6 Å) on MoS layer, MoS anodes exhibit a poor rate performance and easily collapsed structure. To address these issues, the common strategies are enlarging the interlayer spacing to reduce the mechanical strain and increasing the electronic conductivity by adding conductive agents. However, simultaneous implementation of the above strategies by simple methods is currently still a challenge. Herein, MoS anodes on reduced graphene oxide (MoS/rGO) composite were prepared using one-step hydrothermal methods. Owing to the presence of rGO in the synthesis process, MoS possesses a unique scaled structure with large layer spacing, and the intrinsic conductivity of MoS is proved. As a result, MoS/rGO composite anodes exhibit a larger rate performance and better cycle stability than that of anodes based on pure MoS, and the direct mixtures of MoS and graphene oxide (MoS-GO). This work suggests that the composite material of MoS/rGO has infinite possibilities as a high-quality anode material for PIBs.