Designing a High-Performance Lithium Sulfur Batteries Based on Layered Double Hydroxides Carbon Nanotubes Composite Cathode and a Dual-Functional Graphene-Polypropylene-Al2O3 Separator

초록

Designing an optimum cell configuration that can deliver high capacity, fast charge-discharge capability, and good cycle retention is imperative for developing a high-performance lithium-sulfur battery. Herein, a novel lithium-sulfur cell design is proposed, which consists of sulfur and magnesium-aluminum-layered double hydroxides (MgAl-LDH)-carbon nanotubes (CNTs) composite cathode with a modified polymer separator produced by dual side coating approaches (one side: graphene and the other side: aluminum oxides). The composite cathode functions as a combined electrocatalyst and polysulfide scavenger, greatly improving the reaction kinetics and stabilizing the Coulombic efficiency upon cycling. The modified separator enhances further Lit-ion or electron transport and prevents undesirable contact between the cathode and dendritic lithium on the anode. The proposed lithium-sulfur cell fabricated with the as-prepared composite cathode and modified separator exhibits a high initial discharge capacity of 1375 mA h g(-1) at 0.1 C rate, excellent cycling stability during 200 cycles at 1 C rate, and superior rate capability up to 5 C rate, even with high sulfur loading of 4.0 mg cm(-2). In addition, the findings that found in postmortem chracterization of cathode, separator, and Li metal anode from cycled cell help in identifying the reason for its subsequent degradation upon cycling in Li-S cells.

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