Synergistic Regulation of Polysulfides Conversion and Deposition by MOF‐Derived Hierarchically Ordered Carbonaceous Composite for High‐Energy Lithium–Sulfur Batteries

Abstract

To achieve a high sulfur loading is critical for high-energy lithium-sulfur batteries. However, high sulfur loading, especially at a low electrolyte/sulfur ratio (E/S), usually causes low sulfur utilization, mainly caused by the slow redox kinetics of polysulfides and the passivation of the discharge product, poor electrically/ionically conducting Li 2 S. Herein, by using cobalt-based metal organic frameworks (Co-MOFs) as precursors, a Co, N-doped carbonaceous composite (Co, N-CNTs (carbon nanotubes)-CNS (carbon nanosheet)/CFC (carbon fiber cloth)) is fabricated with hierarchically ordered structure, which consists of a free-standing 3D carbon fiber skeleton decorated with a vertical 2D carbon nanosheets array rooted by interwoven 1D CNTs. As an effective polysulfides host, the hierarchically ordered 3D conductive network with abundant active sites and voids can effectively trap polysulfides and provide fast electron/ions pathways to convert them. In addition, Co and N heteroatoms can strengthen the interaction with polysulfides and accelerate its reaction kinetics. More importantly, the interwoven CNTs with Co, N-doping can induce 3D Li 2 S deposition instead of conventional 2D deposition, which benefits improving sulfur utilization. Therefore, for Co, N-CNTs-CNS/CFC electrodes, even at a high sulfur loading of 10.20 mg cm −2 with a low E/S of 6.94, a high reversible areal capacity of 7.42 mAh cm −2 can be achieved with excellent cycling stability.

Zinc Sulfide Decorated on Nitrogen‐Doped Carbon Derived from Metal‐Organic Framework Composites for Highly Reversible Lithium‐Ion Battery Anode

“…The corresponding results of each element are fitted to understand the oxidation state or related structure. Figure b shows XPS C 1s spectrum of the ZnS@NC material, the peaks at 284.5, 285.0, 286.4, and 287.9 eV can be attributed to the carbon species of C−C, C−N, C−O‐C, and C=O, respectively . Additionally, the peaks of ZnS@NC in XPS N 1s spectrum at 398.4 and 399.8 eV are assigned to the nitrogen functional groups of pyridinic N and pyrrolic N, as shown in the Figure c.…”

“…Figure 4b shows XPS C 1s spectrum of the ZnS@NC material, the peaks at 284.5, 285.0, 286.4, and 287.9 eV can be attributed to the carbon species of CÀ C, CÀ N, CÀ O-C, and C=O, respectively. [5,33] Additionally, the peaks of ZnS@NC in XPS N 1s spectrum at 398.4 and 399.8 eV are assigned to the nitrogen functional groups of pyridinic N and pyrrolic N, [34,35] as shown in the Figure 4c. According to the species of carbon and nitrogen, it is confirmed that the nitrogen is doping in the carbon matrix, which can enhance the conductivity and electrochemical performance of material.…”

“…Although the natural wind, water or solar power generation can store electric energy in secondary capacitors or supercapacitors, they still have defects in electrochemical performance, including low energy density, poor multiplier performance, short cycle life, performance degradation caused by low temperature and safety concerns, which cannot meet the application requirements . At the end of the 20th century, lithium cobalt oxide as cathode and graphite as anode electrode were developed, which attracted wide attention due to its high energy density, long cycle life and environmental friendliness . Furthermore, in order to improve the theoretical capacity of carbon materials, it is pointed out that transition metal sulfide materials have the higher theoretical capacity .…”

“…[1][2][3] At the end of the 20th century, lithium cobalt oxide as cathode and graphite as anode electrode were developed, [4] which attracted wide attention due to its high energy density, long cycle life and environmental friendliness. [5] Furthermore, in order to improve the theoretical capacity of carbon materials, it is pointed out that transition metal sulfide materials have the higher theoretical capacity. [6][7][8] Hence, lowcost, non-toxic and high theoretical capacity zinc sulfide has been studied as an alternative anode material.…”

Carbon Nanoarrays Embedded with Metal Compounds for High‐Performance Flexible Supercapacitors

“…[7][8][9][10][11][12][13] Co-MOF derived materials with highly controllable structures have been ideal materials in many fields, such as magnetism, gas adsorption and separation, biomedical and energy storage. [25][26][27][28] Such materials with high electrical conductivity and a large electrolyte contact surface area have been extensively used as electrodes adapted to flexible wearable supercapacitor, [29][30][31][32][33][34] Liion battery, [35,36] zinc-air battery, [37,38] and Na-ion battery. Large horizontal size and ultra-thin thickness lead to very high specific surface area, surface atomic ratio and exposed superficial active sites.…”