Synergistic effect from coaxially integrated CNTs@MoS_(2)/MoO_(2) composite enables fast and stable lithium storage

Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries.However,they suffer from rapid capacity decay and poor kinetics.Herein,we report on synergistic effect from structurally integrated coaxial CNTs@MoS_(2)/MoO_(2) composite material on lithium storage,in which MoS_(2)/MoO_(2) nanosheets are conformally decorated on carbon nanotubes(CNTs).In-situ synchrotron X-ray diffraction measurement is performed to elucidate synergistic effect among three MoS_(2),MoO_(2) and CNTs components for lithium storage.Reaction mechanism exploration reveals that the MoO_(2) component undergoes reversible Li^(+)intercalation via forming a stable Li_(0.98) MoO_(2) phase over a voltage range of 3.0 to 0.01 V vs.Li^(+)/Li,without experiencing the conversion reaction into metallic Mo,which contributes to long-term stability during charge/discharge cycles.Meanwhile,lithium storage of MoS_(2) is through lithium and sulfur reversible reaction after the initial conversion reaction of lithiated MoS_(2) forming Li_(2)S and Mo.The CNTs component enhances electronic conductivity and structural stability by minimizing volume change and reaction strains in the CNTs@MoS_(2)/MoO_(2) composite anode.A desired 68.2%capacity retention upon 2000 cycles at 10 A/g has been demonstrated for the CNTs@MoS_(2)/MoO_(2) anode,revealing prominent reaction kinetics and structural stability for fast and stable lithium storage,superior to various Mo-based anode materials previously reported.The findings from this study,with the unique insight into the role of structural integrity in combining MoS_(2)/MoO_(2) materials with the CNTs substrate,offers a strategy for designing composite anode materials for superior lithium storage performance.