Boosting the Rate Performance of Li–S Batteries via Highly Dispersed Cobalt Nanoparticles Embedded into Nitrogen-Doped Hierarchical Porous Carbon

Abstract

Lithium-sulfur (Li-S) batteries are deemed as one of the most promising alternatives to lithium-ion batteries because of the conspicuous advantages of high energy density and low cost. However, the practical applications of Li-S batteries are hampered by severe shuttle effect and sluggish polysulfide redox conversion. Herein, highly dispersed cobalt nanoparticles (~0.8 wt%) embedded into nitrogen-doped hierarchical porous carbon (Co@N-HPC) are designed as effective electrocatalyst for Li-S batteries, which exhibits a synergistic effect of anchoring and dualdirectional catalytic conversion of polysulfides. The experimental and theoretical studies reveal that Co@N-HPC could not only provide strong chemical affinity to polysulfides but also lower the Li + diffusion barrier and facilitate the precipitation/decomposition of Li 2 S, thus effectively inhibiting the shuttle effect and promoting the reaction kinetics of polysulfides. In addition, the well-dispersed Co nanoparticles in three-dimensional carbon matrix guarantee the exposure of abundant polysulfide confining sites and catalytically active sites. Accordingly, the Li-S batteries assembled with Co@N-HPC functional separators harvest a high rate performance (808.4 mAh g -1 at 10 C), a long-lasting cycle stability (0.055% decay per cycle over 1000 cycles at 4 C), and a superior areal capacity retention (5.78 mAh cm -2 after 100 cycles with a high sulfur loading of 7 mg cm -2 ).

Strengthened d–p Orbital Hybridization through Asymmetric Coordination Engineering of Single-Atom Catalysts for Durable Lithium–Sulfur Batteries

“…Fe K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were employed to further explore the electronic structure and local coordination environment. For the Fe K-edge XANES spectra (Figure 2e), the absorption energy of Fe−N 3 C 2 −C and Fe− N 4 −C locates between that of Fe foil and Fe 2 O 3 , manifesting that the Fe atoms are positively charged 35 , in good accordance with the Fe 2p X-ray photoelectron spectroscopy (XPS) results (Figure S7). In addition, the Fourier-transformed EXAFS (FT-EXAFS) spectra present one dominant peak at 1.47 and 1.41 Å for Fe−N 3 C 2 −C and Fe−N 4 −C, respectively (Figure S8), which can be ascribed to the Fe−N/C coordination.…”

“…One important factor that influences the redox reaction of LiPSs is the interfacial charge transfer kinetics. The electrochemical impedance spectroscopy (EIS) results (Figure S12) demonstrate that the cell with Fe–N 3 C 2 –C shows the smallest electron transfer resistance, which should be ascribed to the excellent conductivity of the sheetlike carbon structure and the asymmetrically coordinated Fe–N 3 C 2 –C sites . In addition, the Li + diffusion kinetics were investigated by cyclic voltammetry (CV) tests with different scan rates (Figures a,b and S13–S14).…”

Self-standing sulfur cathodes enabled by a single Fe site decorated fibrous membrane for durable lithium–sulfur batteries

“…During the past few decades, various strategies have been proposed to solve the above-mentioned issues. 7–14 Among them, the rational design of advanced sulfur cathodes has been demonstrated to be an effective strategy to achieve high sulfur utilization and boost the battery performances. 15 It is worth noting that typical sulfur cathodes are fabricated by coating the mixture of active materials, host substrates and additives ( e.g.…”

Advanced Nanostructured MXene-Based Materials for High Energy Density Lithium–Sulfur Batteries

“…In order to solve these problems, researchers have carried out work in many aspects and adopted various strategies to enhance the cyclic stability of LSBs. For example, materials with high electrical conductivity and chemical adsorption properties were used as sulfur hosts [ 15 , 16 ], functional interlayers were constructed between cathode and separator [ 17 , 18 , 19 ], optimized electrolytes and built advanced lithium anodes were researched and developed [ 20 , 21 , 22 ]. Rational design of sulfur host materials was one of the first widely studied strategies.…”