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

Abstract

The commercialization of lithium−sulfur (Li−S) batteries still confronts great challenges due to the sluggish redox kinetics of sulfur and the shuttle effect of lithium polysulfides. Designing a highly active electrocatalyst is an effective strategy to address the problems caused by complex multistep reactions. Herein, a hybrid composite composed of nitrogen-doped carbonwrapped bimetallic cobalt−iron alloy nanoparticles (NC@CoFe) is derived from a Prussian blue analogue and multiwalled carbon nanotubes (CNTs), which is used as a functional coating on a separator for Li−S batteries. The cross-linked CNTs provide a robust and conductive network for quick charge transfer and sufficient active-site exposure, and the NC@CoFe nanoparticles demonstrate a strong ability for anchoring and catalytic conversion of lithium polysulfides. The specific discharge capacity of the cell with the NC@CoFe/CNT-modified separator can reach 865.4 mA h/g at 3.18 mA/cm 2 (0.5 C) and is 576.3 mA h/g after 300 cycles with a Coulombic efficiency of approximately 98.2%. The cells with a 7.4 mg/cm 2 sulfur loading display a remarkable capacity retention of 77.8% after 100 cycles. The electrocatalyst with functionalized carbonaceous adsorption and alloy nanoparticle catalysis holds substantial promise for advancing the commercialization of durable Li−S batteries.

Enhanced redox kinetics of Prussian blue analogues for superior electrochemical deionization performance

“…42 Due to its nitrogen-containing functional groups and electronegativity in solution, the ppy tubes can be utilized as an ideal substrate for the in situ growth of Mn–NiHCF, where the addition of sodium citrate, potassium ferricyanide, Ni(NO 3 ) 2 ·6H 2 O, and Mn(NO 3 ) 2 ·4H 2 O with stoichiometric ratio thus results in the crystallization of Mn–NiHCF on ppy. 43–45 Fig. 3b depicts the X-ray diffraction (XRD) patterns of the as-prepared samples.…”

Nickel–Nitrogen–Carbon Nanoparticles as Polysulfide Adjustment Layers for Lithium–Sulfur Batteries

“…Lithium–sulfur (Li–S) batteries are distinguished by their impressive theoretical specific capacity of 1675 mAh g –1 and an energy density of 2600 Wh kg –1 , making them a highly promising technology for addressing global energy requirements . Nevertheless, the detrimental shuttle effect of soluble lithium polysulfides (LPSs) in Li–S batteries leads to severe self-discharge, capacity fading, and poor cycling stability. − With the aim of preventing the formation of soluble polysulfide intermediates and mitigating the shuttle effect of polysulfides, there have been numerous reports on modifying separator materials with metallic substrates to confine polysulfides at the cathode, thereby enhancing rate capability and cycling performance. − Recently, metal–nitrogen–carbon (M–N–C) materials have been widely studied owing to their uniform distribution of metal elements and efficient catalytic activity. − Zhang et al synthesized Ni@SAC on N-doped graphene (NG). Structural analysis revealed that Ni@SAC incorporates Ni–N 4 active sites, which facilitate the conversion of polysulfides.…”