RESUMO
The practical application of Li-S batteries is seriously hindered due to its shuttle effect and sluggish redox reaction, which requires a better functional separator to solve the problems. Herein, polypropylene separators modified by MoS2 nanosheets with atomically dispersed nickel (Ni-MoS2 ) are prepared to prevent the shuttle effect and facilitate the redox kinetics for Li-S batteries. Compared with pristine MoS2 nanosheets, Ni-MoS2 nanosheets exhibit both excellent adsorption and catalysis performance for overcoming the shuttle effect. Assembled with this novel separator, the Li-S batteries exhibit an admirable cycling stability at 2 C over 400 cycles with 0.01% per cycle decaying. In addition, even with a high sulfur loading of 7.5 mg cm-2 , the battery still provides an initial capacity of 6.9 mAh cm-2 and remains 5.9 mAh cm-2 after 50 cycles because of the fast convention of polysulfides catalyzed by Ni-MoS2 nanosheets, which is further confirmed by the density functional theory (DFT) calculations. Therefore, the proposed strategy is expected to offer a new thought for single atom catalyst applying in Li-S batteries.
RESUMO
Lithium-sulfur battery is the most promising candidate for the next generation of rechargeable batteries because of the high energy density. However, the severe shuttle effect of lithium polysulfides (LiPSs) and degradation of the lithium anode during cycling are significant issues that hinder the practical application of lithium-sulfur batteries. Herein, monodispersed metal-organic framework (MOF)-modified nanofibers are prepared as building blocks to construct both a separator and a composite polymer electrolyte in lithium-sulfur systems. This building block possesses the intrinsic advantages of good mechanical properties, thermal stability, and good electrolyte affinity. MOFs, grown continuously on the monodispersed nanofibers, can effectively adsorb LiPSs and play a key role in regulating the nucleation and stripping/plating process of the lithium anode. When assembled into the separator, the symmetric battery remains stable for 2500 h at a current density of 1 mA cm-2, and the lithium-sulfur full cell shows improved electrochemical performance. In order to improve the safety property, the composite polymer electrolyte is prepared with the MOF-modified nanofiber as the filler. The quasi-solid-state symmetric battery remains stable for 3000 h at a current density of 0.1 mA cm-2, and the corresponding lithium-sulfur cell can cycle 800 times at 1 C with a capacity decay rate of only 0.038% per cycle.
RESUMO
Lithium metal is an ideal anode for high-energy-density batteries. However, the low Coulomb efficiency and the generation of dendrites pose a significant limitation to its practical application, while the excess lithium in the battery also generates serious safety concerns. Herein, a layer-by-layer optimized multilayer structure integrating an artificial solid electrolyte interphase (LiF) layer, a lithiophilic (LixAu alloy) layer, and a lithium compensation layer is reported for a lean-lithium metal battery, where each layer acts synergistically to stabilize the lithium deposition behaviors and enhances the cycling performance of the battery. The optimized anode could effectively induce homogeneous reversible lithium deposition under the synergistic effect of multilayer films and keep the integrity of the morphological structure unbroken during the deposition. The presence of the lithium compensation layer allows the half-cell to have a high initial CE of 158.9%, and the action of the LiF layer and lithiophilic layer maintains an average CE of 98.8% over 160 cycles, which further demonstrates the stability of the structure. As a result, when combined with LiFePO4 cathode, an initial capacity of 148 mAh g-1 and a retention rate of 97.5% over 130 cycles were achieved.