Supernormal Conversion Anode Consisting of High-Density MoS₂ Bubbles Wrapped in Thin Carbon Network by Self-Sulfuration of Polyoxometalate Complex

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 MoS solid bubbles of hundreds of nanometers in size, which are conformally encapsulated by thin-layer 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 MoS-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 MoS-based anodes even with ultrathin 2D nanosheets. Partially benefiting from the electroactivity of a dithiooxamide (DTO)-derivate carbon network, the reversible capacity of MoS-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.

Glucose‐Induced Synthesis of 1T‐MoS2/C Hybrid for High‐Rate Lithium‐Ion Batteries

“…To overcome these shortcomings, a large amount of efforts was devoted to modify the electrochemical performance of 2H‐MoS 2 . Two general ways are: 1) designing nanostructure materials, such as nanotubes, nanosheets, and nanospheres; 2) hybridizing 2H‐MoS 2 with carbonaceous materials, such as graphene . Compared with 2H phase MoS 2 , 1T phase MoS 2 presents a metallic transport behavior and its electric conductivity is approximately 5 orders of magnitudes higher than that in semiconducting 2H‐MoS 2 .…”

MoS2/carbon composites prepared by ball-milling and pyrolysis for the high-rate and stable anode of lithium ion capacitors

“…MoS 2 (molybdenum disulde), as one of the family of bidimensional layered metal suldes, has attracted many researchers' attention. [20][21][22] It possesses large interlayers distance (0.615 nm) and well-dened 2D plane structure. MoS 2 demonstrates low reaction potential and high theoretical capacity of 669 mA h g À1 as promising anode materials.…”

Constructing Hollow Ni0.2Co0.8S@rGO Composites at Low Temperature Conditions as Anode Material for Lithium‐Ion batteries

“…The capacity decreases rapidly at the first 100 cycles, then raises slowly, and maintains stable eventually at both 5 and 10 A g −1 . The capacity fading before 100 cycles may be due to the hysteretic electrolyte wetting at higher current density, which requires more cycles to activate the electrode materials . The increasing capacity upon cycling can be attributed to the electrochemical activation, pseudocapacitive behavior, and the reversible formation of SEI film, which would be clarified below ,.…”

“…The capacity fading before 100 cycles may be due to the hysteretic electrolyte wetting at higher current density, which requires more cycles to activate the electrode materials. [44] The increasing capacity upon cycling can be attributed to the electrochemical activation, pseudocapacitive behavior, and the reversible formation of SEI film, which would be clarified below. [45,46] The comparison of electrochemical performances of Ni 0.2 Co 0.8 S-2.5@rGO with other CoS-based materials is summarized in Table S1.…”