Interlayer-expanded MoS2 nanoflowers anchored on the graphene: A high-performance Li+/Mg2+ co-intercalation cathode material

[Display omitted] •• The interplanar distance of MoS2 is expanded from 0.62 nm to 0.885 nm.•• Li+/Mg2+ hybrid-ion batteries realize the Li+/Mg2+ co-intercalation even at 1000 mA g−1.•• A “boost effect” of intercalated Li+ on Mg2+ was found and demonstrated.•• A reversible capacity of 123.3 mAh g−1 was exhibited at 1000 mA g−1 after 2000 cycles. Li+/Mg2+ hybrid-ion batteries (LMIBs), integrating the merits of lithium ion batteries (LIBs) and magnesium ion batteries (MIBs) are considered as an attractive alternative of next generation metal secondary batteries. Due to the sluggish solid-state diffusion kinetic induced by the strong Coulombic interaction between Mg2+ and host materials, pristine MoS2 with interplanar distance of 0.62 nm exhibits inferior electrochemical performance for LMIBs with only Li+ intercalation. Herein, we report an oxygen-incorporated MoS2 (O-MoS2) nanoflower anchored on graphene (O-MoS2/G) with the interplanar distance of O-MoS2 from 0.62 nm expanded to 0.885 nm. Even at 1000 mA g−1, the expanded interlayer spacing can still ensure the Mg2+ and Li+ intercalation/deintercalation into/from the host material simultaneously. Meanwhile, this configuration can effectively reduce the diffusion barrier of metal ions, increase the intercalated number of ions, and enhance the stability of structure. In addition, we found and demonstrated the intercalated Li+ had a boosting effect to the intercalation kinetics of Mg2+. Compared with the MIBs, the migration energy barriers of Mg2+ under the existence of Li+ intercalating into MoS2 is reduced from 0.36 eV to 0.16 eV, meanwhile the corresponding intercalation capacity and diffusion coefficient of Mg2+ are 1.38 and 7.1 times as large as MIBs. As expect, the O-MoS2/G exhibits superior rate capability and cycling performance with a reversible capacity of 123.3 mAh g−1 after 2000 cycles charge–discharge processes at 1000 mA g−1.