Polysulfide shuttling and uncontrollable lithium dendrite growth have hampered the application of lithium–sulfur (Li–S) batteries. Although various materials have been utilized to overcome these obstacles, simple and scalable methods are still needed for Li–S battery commercialization. It is shown for the first time that the layer‐by‐layer (LbL) self‐assembly of 2D nanomaterials can be used to controllably fabricate multifunctional separators that simultaneously trap polysulfides and suppress lithium dendrite growth. The double‐sided “nanobrick wall” structure, constructed by MoS2/poly(diallyl dimethyl ammonium chloride) hybrid in conjunction with poly(acrylic acid) (PAA), provides a physical shield against polysulfides and the chemical adsorption of such species by MoS2 and PAA. At the same time, the robust and Li‐ion conducting MoS2 layers strengthen the separator and regulate Li deposition, thereby effectively suppressing Li dendrite formation. As a result, a simple sulfur cathode battery with an ultralight separator coating (0.10 mg cm−2) is able to achieve an outstanding cycle stability with a capacity decay as low as 0.029% per cycle over 2000 cycles and a reversible areal capacity ≈2.0 mAh cm−2 at 1 C. The proposed LbL approach opens the door to the simple, scalable, and economic fabrication of advanced functional separators for use in the real world.
The conversion of GO to RGO, using biodegradable CNC, offers a sustainable approach to large-scale preparation of highly biocompatible and easily dispersed RGO.
Electric-field-induced transient pore formation (electroporation) in synthetic unilamellar dioleoylphosphatidylcholine vesicles of 178-nm diameter is utilized for the preparation of subnanometer-size PbS quantum dots. With Pb2+ ions originally entrapped in the vesicles and S2- ions placed in the bulk, their reaction is initiated by the opening of pores and occurs in the bulk. The ensuing self-aggregation of PbS is slowed to the hour and day time scales by its adsorption at the exterior surface of the vesicles. The growth of the particles in the molecular size regime is found to exhibit novel, time-dependent, oscillating red and blue shifts of the characteristic UV absorption band. On the basis of similarities between the oscillating trend of the experimentally observed transition energy and that of the calculated highest occupied molecular orbital-lowest unoccupied molecular orbital gap of (PbS)n clusters with n = 1-9, the wavelengths of the sequential spectral peaks can be assigned to the PbS monomer (237.5 nm), dimer (282 nm), tetramer (232 nm), hexamer (281 nm), octamer (234.5 nm), and nonamer (278-280 nm). Growth beyond the octamer is associated with the customary monotonic red shift of the absorption band. Under the experimental conditions used, a stable system is reached with unchanging spectral features after 20 days. This solution is estimated to contain 1.82 x 10(-5) M (PbS)9 particles, each with a greatest dimension of <9 A.
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