In‐Situ Synthesis of Carbon‐Encapsulated Atomic Cobalt as Highly Efficient Polysulfide Electrocatalysts for Highly Stable Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries have been considered as one of the most promising electrochemical energy storage systems because of their high energy density. However, a series of issues severely limit the practical performances of Li–S batteries such as low conductivity, significant volume change, and shuttle effect. The hollow carbon spheres with huge voids and high electrical conductivity are promising as sulfur hosts. Unfortunately, the nonpolar nature of carbon materials cannot prevent the shuttle effect effectively. In this case, the atomic cobalt is introduced to a nitrogen‐doped hollow carbon sphere (ACo@HCS) through polymerization and controlled pyrolysis. The atomic cobalt dopants not only act as active sites to restrict the shuttle effect, but also can promote the kinetics of the sulfur redox reactions. ACo@HCS acting as sulfur host exhibits a high discharge capacity (1003 mAh g−1) at a 1.0 C rate after 500 cycles, and the corresponding decay rate is as low as 0.002% per cycle. This exciting work paves a new way to design high‐performance Li–S batteries.

Interfacial Engineering of Binder‐Free Janus Separator with Ultra‐Thin Multifunctional Layer for Simultaneous Enhancement of Both Metallic Li Anode and Sulfur Cathode

“…To further analyze the chemical structure, NMR spectroscopy of the self-standing CTP nanofilm was performed (Figure 3f). And the 13 C NMR spectrum indicates two explicit chemical shift peaks at 163.8 and 43.7 ppm, which correspond to the C of triazine and piperazine, respectively. [39] It affirms that the CTP nanofilm consists of two components.…”

“…The X-ray photoelectron spectroscopy was conducted by XPS (ThermoFisher, ESCALAB250Xi). 13 C NMR spectrum of self-standing CTP nanofilm was used to analyze the chemical structure by Bruker 400M.…”

“…[8] In terms of the metallic Li anode, the Li-dendrite growth triggered by the nonuniform Li dissolution/deposition will induce an internal short circuit. [9] To counteract these negative consequences, researchers have developed hosts for sulfur encapsulation in cathode, [10][11][12][13] lithium anode protection, [14] and separator modification to prevent lithium polysulfides (LiPSs) from shuttling. [15][16][17] Proposing a rational design strategy for simultaneous enhancement of both metallic Li anode and sulfur cathode is of great significance.…”

Tuning the Delithiation State of LiNi0.5Co0.2Mn0.3O2 Enabling the Electronic Structure Modification to Enhance the Conversion of Polysulfides in a Lithium–Sulfur Battery

“…Approximately three-quarters of the capacity of LSBs is provided by the conversion from long-chain LiPSs to insoluble Li 2 S 2 /Li 2 S, and the poor reaction kinetics of this process leads to the accumulation of LiPSs on the cathode side, shuttling to the anode side under the influence of the concentration gradient on both sides of the cathode–anode electrode. Furthermore, the accumulation of LiPSs leads to the random precipitation and agglomeration of Li 2 S into large particles with high activation energy, making it difficult to be reused in the subsequent reaction. , Therefore, the problem of sluggish redox kinetics of LiPSs/sulfides blocked on the cathode side still needs to be solved, and a more efficient method is urgently needed, which not only anchors LiPSs but also accelerates the subsequent catalytic conversion of LiPSs to improve the long-term cycling stability of LSBs. , Nowadays, the exploration of electrocatalysts for the catalytic conversion of LiPSs has attracted extensive attention from researchers focusing on LSBs. − …”

“…33,34 Therefore, the problem of sluggish redox kinetics of LiPSs/sulfides blocked on the cathode side still needs to be solved, and a more efficient method is urgently needed, which not only anchors LiPSs but also accelerates the subsequent catalytic conversion of LiPSs to improve the long-term cycling stability of LSBs. 35,36 the exploration of electrocatalysts for the catalytic conversion of LiPSs has attracted extensive attention from researchers focusing on LSBs. 37−42 Researchers have demonstrated that single-atom catalyst and transition-metal compounds exert catalytic effects on LiPSs, not only effectively inhibiting their shuttling through chemical binding but also significantly accelerating their redox reaction.…”