title: Interlayer-expanded molybdenum disulfide nanocomposites for electrochemical magnesium storage.
abstract: Mg rechargeable batteries (MgRBs) represent a safe and high-energy battery technology but suffer from the lack of suitable cathode materials due to the slow solid-state diffusion of the highly polarizing divalent Mg ion. Previous methods improve performance at the cost of incompatibility with anode/electrolyte and drastic decrease in volumetric energy density. Herein we report interlayer expansion as a general and effective atomic-level lattice engineering approach to transform inactive intercalation hosts into efficient Mg storage materials without introducing adverse side effects. As a proof-of-concept we have combined theory, synthesis, electrochemical measurement, and kinetic analysis to improve Mg diffusion behavior in MoS2, which is a poor Mg transporting material in its pristine form. First-principles simulations suggest that expanded interlayer spacing allows for fast Mg diffusion because of weakened Mg-host interactions. Experimentally, the expansion was realized by inserting a controlled amount of poly(ethylene oxide) into the lattice of MoS2 to increase the interlayer distance from 0.62 nm to up to 1.45 nm. The expansion boosts Mg diffusivity by 2 orders of magnitude, effectively enabling the otherwise barely active MoS2 to approach its theoretical storage capacity as well as to achieve one of the highest rate capabilities among Mg-intercalation materials. The interlayer expansion approach can be leveraged to a wide range of host materials for the storage of various ions, leading to novel intercalation chemistry and opening up new opportunities for the development of advanced materials for next-generation energy storage.
authors.affiliation: Department of Electrical and Computer Engineering and Materials Science and Engineering Program and ‡Department of Physics, University of Houston , Houston, Texas 77204, United States.
authors.forename: Yanliang
authors.initials: Y
authors.lastname: Liang
authors.forename: Hyun Deog
authors.initials: HD
authors.lastname: Yoo
authors.forename: Yifei
authors.initials: Y
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Shuai
authors.forename: Hector A
authors.initials: HA
authors.lastname: Calderon
authors.forename: Francisco Carlos
authors.initials: FC
authors.lastname: Robles Hernandez
authors.forename: Lars C
authors.initials: LC
authors.lastname: Grabow
authors.forename: Yan
authors.initials: Y
authors.lastname: Yao
keywords: Magnesium rechargeable batteries; diffusion kinetics; intercalation materials; molybdenum disulfide; nanocomposites