Abstract
Lithium-sulfur batteries are very promising next-generation energy storage batteries due to their high theoretical specific capacity. However, the shuttle effect of lithium-sulfur batteries is one of the important bottlenecks that limits its rapid development. Herein, physical and chemical dual adsorption of lithium polysulfides are achieved by designing a novel framework structure consisting of MnO2, reduced graphene oxide (rGO), and carbon nanotubes (CNTs). The framework-structure composite of MnO2/rGO/CNTs is prepared by a simple hydrothermal method. The framework exhibits a uniform and abundant mesoporous structure (concentrating in ~12 nm). MnO2 is an α phase structure and the α-MnO2 also has a significant effect on the adsorption of lithium polysulfides. The rGO and CNTs provide a good physical adsorption interaction and good electronic conductivity for the dissolved polysulfides. As a result, the MnO2/rGO/CNTs/S cathode delivered a high initial capacity of 1201 mAh g−1 at 0.2 C. The average capacities were 916 mAh g−1, 736 mAh g−1, and 547 mAh g−1 at the current densities of 0.5 C, 1 C, and 2 C, respectively. In addition, when tested at 0.5 C, the MnO2/rGO/CNTs/S exhibited a high initial capacity of 1010 mAh g−1 and achieved 780 mAh g−1 after 200 cycles, with a low capacity decay rate of 0.11% per cycle. This framework-structure composite provides a simple way to improve the electrochemical performance of Li-S batteries.
Highlights
With the development of science and technology, the most widely used lithium-ion battery has gradually failed to meet the needs of technological development due to its limited capacity [1,2]
Was used to generate MnO2 in situ, the composite of reduced graphene oxide (rGO)/MnO2 was obtained after the addition was used to generate MnO2 in situ, the composite of rGO/MnO2 was obtained after the addition of KMnO and H PO
One half of the GO was replaced by oxidized carbon nanotubes (CNTs) and the other conditions were maintained with the rGO/MnO2
Summary
With the development of science and technology, the most widely used lithium-ion battery has gradually failed to meet the needs of technological development due to its limited capacity [1,2]. In order to further improve the capacity of secondary batteries, researchers turned their research attention to other battery systems with high energy densities. The typical discharge reaction of Li-S batteries is 16Li + S8 →8Li2 S [8] During this reaction process, a series of soluble intermediates Li2 Sx (Li2 S4 , Li2 S6 , and Li2 S8 ) are produced, which can dissolve in the electrolyte and move between the positive and negative electrodes. A series of soluble intermediates Li2 Sx (Li2 S4 , Li2 S6 , and Li2 S8 ) are produced, which can dissolve in the electrolyte and move between the positive and negative electrodes This phenomenon is often called the shuttle effect, causing the negative electrode to corrode and the capacity to be significantly reduced. Physical adsorption and chemical adsorption are two commonly used methods to limit the shuttling of lithium polysulfides
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