Supernormal Conversion Anode Consisting of High-Density MoS2 Bubbles Wrapped in Thin Carbon Network by Self-Sulfuration of Polyoxometalate Complex Peiyuan Wang,† Jing Tian,†,‡ Jiulin Hu,†,‡ Xuejun Zhou,† and Chilin Li*,† †
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Ding Xi Road, Shanghai 200050, China ‡ University of Chinese Academy of Sciences, Beijing 100039, China S Supporting Information *
ABSTRACT: Large-capacity conversion electrodes are highly required to raise the energy density of batteries. However, their undesired phase segregation and volume expansion during cycling lead to the motivation for nanofabrication and nanochemistry of active species in order to decrease “dead mass” and promote better construction of conductive networks. However, the inactivity of the conductive skeleton and loose nanostructure would compromise the energy density of the electrode. The integration of large-sized (high-density) grains into an electroactive conductive network in a compact way is still a big challenge. Here we report a proof-of-concept prototype consisting of unusual MoS2 solid bubbles of hundreds of nanometers in size, which are conformally encapsulated by thinlayer carbon. The seamless welding between this carbon coating and the surrounding broader carbon substrate can effectively avoid the peel-off of active species and breakage of the conductive network. This MoS2−C composite is achieved by simultaneous self-sulfuration and self-carbonization of a polyoxometalate (POM)-based chelate, and its Li-storage performance is superior to most MoS2-based anodes even with ultrathin 2D nanosheets. Partially benefiting from the electroactivity of a dithiooxamide (DTO)-derivate carbon network, the reversible capacity of MoS2−C by pyrolyzing the POM−DTO chelate can reach 1500−2000 mAh/g at 0.5−1 A/g even after 700 cycles and be maintained around 1000 mAh/g under as high as 10−20 A/g. KEYWORDS: MoS2, conversion anode, carbon network, polyoxometalate, Li-ion batteries
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nanoengineering and porous architecture are necessary in order to shorten the electron transport distance and facilitate electrolyte infiltration.4,5,9 Loose nanostructures consisting of extremely small nanoparticles (usually
