2D hierarchical yolk-shell heterostructures as advanced host-interlayer integrated electrode for enhanced Li-S batteries

Abstract

Lithium sulfur (Li-S) batteries hold great promising for high-energy-density batteries, but appear rapid capacity fading due to the lack of overall and elaborated design of both sulfur host and interlayer. Herein, we developed a novel two-dimensional (2D) hierarchical yolk-shell heterostructure, constructed by a graphene yolk, 2D void and outer shell of vertically aligned carbon-mediated MoS 2 nanosheets (G@void@MoS 2 /C), as advanced host-interlayer integrated electrode for Li-S batteries. Notably, the 2D void, with a typical thickness of ∼80 nm, provided suitable space for loading and confining nano sulfur, and vertically aligned ultrathin MoS 2 nanosheets guaranteed enriched catalytically active sites to effectively promote the transition of soluble polysulfides. The conductive graphene yolk and carbon mediated shell sufficiently accelerated electron transport. Therefore, the integrated electrode of G@void@MoS 2 /C not only exceptionally confined the sulfur/polysulfides in 2D yolk-shell heterostructures, but also achieved catalytic transition of the residual polysulfides dissolved in electrolyte to solid Li 2 S 2 /Li 2 S, both of which synergistically achieved an extremely low capacity fading rate of 0.05% per cycle over 10 0 0 times at 2 C, outperforming most reported Mo based cathodes and interlayers for Li-S batteries. 2D hierarchical yolkshell heterostructures developed here may shed new insight on elaborated design of integrated electrodes for Li-S batteries.

Improve redox activity and cycling stability of the lithium‐sulfur batteries via in situ formation of a sponge‐like separator modification layer

“…Typically, at 0.2C, the discharge capacities from the fifth to the 35th cycle were reduced by 75.1 mAh g −1 for the cell with PE separator, which probably due to the diffusion of the soluble polysulfides to the anode side through the root‐like membrane. As verified by the previous work, the polysulfide can undergo an irreversible electrochemical reaction with the metal Li, leading to the loss of the cathode active material. The cell with KB/PE separator, another control membrane, exhibits a 19.6 mAh g −1 decrease in discharge capacities, further confirming a degradation of performance recovery capability due to the shuttle effect of polysulfides.…”

“…Unfortunately, because of the weak adsorption between the polar polysulfides and nonpolar carbon, the shuttle effect of soluble polysulfides cannot be effectively suppressed with these separators. [14][15][16] Modifying the carbon-coating layer with polysulfide anchoring materials, such as polar metal oxides [17][18][19][20][21][22][23][24] and polymers, [25][26][27][28][29] and MXene 30 can bring additional advantages and thus effectively restrain the shuttle effect of polysulfide. The trapped polysulfide on the modified carbon layer is expected to block the Li + diffusion channels.…”

Efficient polysulfide blocker from conductive niobium nitride@graphene for Li-S batteries

“…20 mg NbN/G or graphene was added into 1 mM Li 2 S 6 solution of 5 ml. Digital photos were taken before and after adsorption [27] . Finally, the UV-vis spectra were performed to verify the residual concentration of Li 2 S 6 solution [28 , 29] .…”

Rational design of MoS2 nanosheets decorated on mesoporous hollow carbon spheres as a dual-functional accelerator in sulfur cathode for advanced pouch-type Li–S batteries

“…Since 2D MoS 2 nanosheets were demonstrated as effective catalyst for accelerating LiPSs conversion [36] , numerous attentions have been attracted [37][38][39][40][41][42] . Considering the limited electrical conductivity of MoS 2 , most researchers utilized graphene to facilitate electron transfer [41][42][43][44][45] . Nevertheless, the open channel structure in graphene based electrode is unfavorable for the restriction of soluble LiPSs.…”