Enhancing Sulfur Redox Conversion of Active Iron Sites by Modulation of Electronic Density for Advanced Lithium‐Sulfur Battery

Abstract

Despite lithium‐sulfur (Li‐S) batteries possessing ultrahigh energy density as great promising energy storage devices, the suppressing shuttle effect and improving sulfur redox reaction (SROR) are vital for their practical application. Developing high‐activity electrocatalysts for enhancing the SROR kinetics is a major challenge for the application of Li‐S batteries. Herein, single‐molecule iron phthalocyanine species are anchored on the N and P dual‐doped porous carbon nanosheets (Fe‐NPPC) via axial Fe‐N coordination to optimize the electronic structure of active centers. The Fe‐NPPC can promote the catalytic conversion of polysulfides by modulation of the electronic density in active moieties, endowing the Li‐S battery with a high reversible capacity of 1023 mAh g−1 at 1 C as well as an ultralow capacity decay of 0.035% per cycle over 1500 cycles. Even with a high sulfur loading of 7.1 mg cm−2, the Li‐S battery delivers a high areal capacity of 4.8 mAh cm−2 after 150 cycles at 0.2 C. With further increasing the sulfur loading to 9.2 mg cm−2, an excellent areal capacity of up to 9.3 mAh cm−2 is obtained at 0.1 C.

Tandem Carbon Hollow Spheres with Tailored Inner Structure as Sulfur Immobilization for Superior Lithium–Sulfur Batteries

“…The electrolyte constitutes the maximum weight fraction of the LSBs, and the mass ratio of electrolyte to sulfur (E/S) represents the most important lever for changing the specific energy of the battery. [53,54] In this experiment, the WSYCS2@CF/S positive electrode with the same sulfur-loading of 12.5 mg cm −2 is used to perform a 0.1C cycle test after 0.05C pre-activation with an E/S ratio of 15, 10 and 5 μL mg −1 (Figure 5b). As the amount of electrolyte injected decreases, battery performance deteriorates.…”

Bifunctional Additive for Lithium–Sulfur Batteries Based on the Metal–Phthalocyanine Complex

“…Recently, catalytic LiPS conversion of the discharge products (S/Li 2 S) has been demonstrated as an effective strategy to reduce the amount of LiPS in the electrolyte and further elevate the sulfur utilization of the cathode. For example, transition metal phosphides, such as FeP, CoP, MoP, and NiP, nanocatalysts; such as metal oxides and metal sulfides; and transition metal phthalocyanine compounds (M = Fe, Co, Cu, and Zn), have rendered excellent electrocatalytic properties in energy storage devices, thereby improving the overall utilization of sulfur. − Therefore, it is extremely important to suppress the shuttle effect and improve the reaction kinetics of polysulfides to obtain high-performance LSBs.…”