A freestanding MoO₂-decorated carbon nanofibers interlayer for rechargeable lithium sulfur battery

Abstract

Summary Lithium‐sulfur (Li‐S) battery based on sulfur cathodes is of great interest because of high capacity and abundant sulfur source. But the shuttling effect of polysulfides caused by charge‐discharge process results in low sulfur utilization and poor reversibility. Here, we demonstrate a good approach to improve the utility of sulfur and cycle life by synthesizing carbon nanofibers decorated with MoO2 nanoparticles (MoO2‐CNFs membrane), which plays a role of multiinterlayer inserting between the separator and the cathode for Li‐S battery. The S/MoO2‐CNFs/Li battery showed a discharge capacity of 6.93 mAh cm−2 (1366 mAh g−1) in the first cycle at a current density of 0.42 mA cm−2 and 1006 mAh g−1 over 150 cycles. Moreover, even at the highest current density (8.4 mA cm−2), the battery achieved 865 mAh g−1. The stable electrochemical behaviors of the battery has achieved because of the mesoporous and interconnecting structure of MoO2‐CNFs, proving high effect for ion transfer and electron conductive. Furthermore, this MoO2‐CNFs interlayer could trap the polysulfides through strong polar surface interaction and increases the utilization of sulfur by confining the redox reaction to the cathode.

Freestanding graphitic carbon nitride‐based carbon nanotubes hybrid membrane as electrode for lithium/polysulfides batteries

“…Simultaneously, the absorption peaks at about 280 and 300 nm (S 6 2− ) of Li 2 S 6 solution with g‐C 3 N 4 /CNTs are the weakest than that of Li 2 S 6 solution with CNTs and g‐C 3 N 4 . The result demonstrates that g‐C 3 N 4 and CNTs both have trapping for polysulfides, which confinement effect for lithium polysulfides are significant to inhibit the shuttle effect in redox process.…”

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

“…Interestingly, the calculated D Li+ values increased from 8.0 × 10 −8 (C1), 3.0 × 10 −8 (C2), and 6.8 × 10 −8 cm 2 s −1 (A) for the routine PE separator to 1.6 × 10 −7 (C1), 3.2 × 10 −8 (C2), and 7.6 × 10 −8 (A) for the KB/PE membrane, and 2.7 × 10 −7 (C1), 4.2 × 10 −8 (C2), and 1.4 × 10 −7 cm 2 s −1 (A) for the KB‐TPS/PE separator, which is consistent with the measured Li + conductance results (Figure 2B). This improvement in the Li + diffusion coefficient of the modified separator was also proofed by the EIS technique . The details were given in the Figure S7.…”

“…The Li + diffusion coefficients (D Li+ ) of PE, KB/PE, and KB‐TPS/PE separators in the electrolyte were tested by the cyclic voltammetry (CV) technique. The KB/S composite cathode material with 80 wt.% S was prepared according to our previous work . The cathode slurry was obtained by mixing 70 wt.% KB/S composite, 20 wt.% carbon nanotubes, and 10 wt.% acrylonitrile multi‐copolymer in a planetary stirring defoaming machine.…”

Synergistic effect of sulfur on electrochemical performances of carbon‐coated vanadium pentoxide cathode materials with polyvinyl alcohol as carbon source for lithium‐ion batteries

“…In order to deal with these problems, many researchers believe that sulfur is required to be hosted on some matrix materials, such as carbon material, metal compounds, conductive polymer materials, and so on. Lately, metal oxides as sulfur host material have received extensive attention in recent years due to the strong physical and chemical adsorption between M─O (M═Ti, Sn, Fe, Mo …) bond structure and sulfur …”