In Situ Trapping Strategy Enables a High-Loading Ni Single-Atom Catalyst as a Separator Modifier for a High-Performance Li–S Battery

Abstract

The poor electrochemical reaction kinetics of Li polysulfides is a key barrier that prevents the Li−S batteries from widespread applications. Ni single atoms dispersed on carbon matrixes derived from ZIF-8 are a promising type of catalyst for accelerating the conversion of active sulfur species. However, Ni favors a square-planar coordination that can only be doped on the external surface of ZIF-8, leading to a low loading amount of Ni single atoms after pyrolysis. Herein, we demonstrate an in situ trapping strategy to synthesize Ni and melamine-codoped ZIF-8 precursor (Ni-ZIF-8-MA) by simultaneously introducing melamine and Ni during the synthesis of ZIF-8, which can remarkably decrease the particle size of ZIF-8 and further anchor Ni via Ni−N 6 coordination. Consequently, a novel high-loading Ni single-atom (3.3 wt %) catalyst implanted in an N-doped nanocarbon matrix (Ni@NNC) is obtained after high-temperature pyrolysis. This catalyst as a separator modifier shows a superior catalytic effect on the electrochemical transitions of Li polysulfides, which endows the corresponding Li−S batteries with a high specific capacity of 1232.4 mA h g −1 at 0.3 C and an excellent rate capability of 814.9 mA h g −1 at 3 C. Furthermore, a superior areal capacity of 4.6 mA h cm −2 with stable cycling over 160 cycles can be achieved under a critical condition with a low electrolyte/sulfur ratio (8.4 μL mg −1 ) and high sulfur loading (4.85 mg cm −2 ). The outstanding electrochemical performances can be attributed to the strong adsorption and fast conversion of Li polysulfides on the highly dense active sites of Ni@NNC. This intriguing work provides new inspirations for designing high-loading single-atom catalysts applied in Li−S batteries.

Separator Modified by Carbon-Encapsulated CoFe Alloy Nanoparticles Supported on Carbon Nanotubes for Advanced Lithium–Sulfur Batteries

“…However, the physical and chemical adsorption of lithium polysulfides cannot effectively suppress the shuttle effect under long cycles and high-sulfur-loading conditions . Moreover, the sluggish redox of sulfur leads to the accumulation of lithium polysulfides in the electrolyte, which causes the shuttle effect and capacity attenuation. , In recent years, many kinds of metal nanostructures (e.g., Co, Ni, Sn, Fe, and Se/Te) as electrocatalysts have been developed in combination with chemical adsorption to effectively accelerate the redox reaction and alleviate the shuttle effect, thus improving the performance of Li–S batteries. Compared with monometal nanostructures, alloys are regarded as a significant group of heterogeneous catalysts consisting of mixed metallic components, which further increase catalytic activity, stability, and selectivity .…”

Nitrogen-phosphorus dual-doped auricularia auricula porous carbon as host for Li-S battery

“…Also, carbon materials with high specific surface area can effectively absorb more lithium sulfide and then alleviate its dissolution in the electrolyte [6]. In short, combining with carbon materials can greatly enhance the performance of sulfur electrode [7].…”

Cobalt Sulfide Nanoparticles Embedded Carved Carbon Nanoboxes Dispersed in Iron Single-Atom decorated Multiwalled Carbon Nanotube Porous Structure as a Host Material for Lithium–Sulfur Batteries

“…It is evident that several approaches have been developed to improve the electrochemical performances of LSBs, targeting mainly the shuttling effect of polysulfides. These approaches include use of strong polysulfide adsorbents, such as metal sulfides, , incorporation of strong catalysts toward polysulfide conversion reactions, such as single atom catalysts, − ,− and introduction of conductive heteroatom-doped carbonaceous networks to enhance overall electrical conductivities of the cathode and to offer physical confinement to lessen escape of polysulfides. , It is desired to combine all of these approaches to fabricate composite sulfur host materials for LSBs. Such attempts, however, have been rarely, if not never, reported.…”