Ionic‐Liquid‐Assisted Synthesis of FeSe–MnSe Heterointerfaces with Abundant Se Vacancies Embedded in N,B Co‐Doped Hollow Carbon Microspheres for Accelerating the Sulfur Reduction Reaction

Abstract

Currently, extensive research efforts are being devoted to suppressing the shuttle effect of polysulfides. The uncontrollable deposition of insulating Li2S onto the surface of sulfur host materials dramatically inhibits the continuous reduction of polysulfides in lithium–sulfur (Li–S) batteries. Herein, N,B co‐doped hollow carbon microspheres embedded with dense FeSe–MnSe heterostructures and abundant Se vacancies (FeSe–MnSe/NBC) are rationally designed and synthesized via a facile hydrothermal reaction using ionic liquids as dopants. The introduction of abundant heterostructures subtly guides Li2S nucleation and deposition in 3D frameworks, thus avoiding the formation of the Li2S passivation layer and allowing for continuous Li+ diffusion and subsequent nucleation of Li2S. Owing to these beneficial features, Li–S batteries comprising an FeSe–MnSe/NBC electrode exhibit significantly improved performance, including a high initial capacity of 1334 mAh g−1 at 0.2 C and ultralong cycle stability with a low capacity fading rate of 0.029% cycle−1 over 1000 cycles at 1.0 C. Remarkably, the FeSe–MnSe/NBC pouch cell delivers a considerable areal capacity of 3.6 mAh cm−2 at 0.1 C. This study provides valuable insight into heterostructures and Se vacancies for developing practical Li–S batteries.

Amorphous/crystalline heterostructure design enables highly efficient adsorption–diffusion–conversion of polysulfides for lithium–sulfur batteries

“…Evidently, the peak of c-Bi 2 Se 3 /a-BiO x at 58.9 eV could correspond to the SeO x oxidized species. 25,47 Overall, the XPS results together with the above TEM, EDS and XRD analyses indicate that the surface oxidation of Bi 2 Se 3 to form a thin a-BiO x layer is successfully achieved.…”

“…Through this way, the advantages of different components could be commendably integrated to obtain the synergistic performance of strong LiPS adsorption, fast ion diffusion and excellent catalytic activity. 24–26 As a good example, a TiO 2 /TiN heterostructure composed of adsorptive TiO 2 and conductive TiN achieved smooth trapping–diffusion–conversion of LiPSs and greatly improved LiPS utilization. 27 Up to now, a variety of heterostructured materials, such as MoS 2 /MoO 3 , WS 2 /WO 3 , MoS 2 /MoN, SnO 2 /Mo 2 N, NiS 2 /WS 2 , and V 2 O 3 /V 8 C 7 , have been synthesized as high-performance sulfur electrocatalysts.…”

A hollow nano-flower NiCo2O4@Nb2CTx MXene heterostructure via interfacial engineering for high-performance flexible supercapacitor electrodes

“…In addition, the negative values of the OH– adsorption energies indicate that the processes involved are spontaneous and exothermic and that the systems studied are then thermodynamically favorable. 49,70…”

Oxygen Vacancies in Bismuth Tantalum Oxide to Anchor Polysulfide and Accelerate the Sulfur Evolution Reaction in Lithium–Sulfur Batteries

“…The Bi 3 TaO 7−x exhibits the highest redox current response of 20 mA among these samples. In addition, the Bi 3 TaO 7−x electrode delivers the highest exchange current density in both reduction and oxidation processes and the smallest Tafel slope at the same time, as shown in Figure 5 b [ 30 ]. Compared with those of Bi 3 TaO 7 and MC, the electrochemical impedance spectroscopy (EIS) measurement results show that Bi 3 TaO 7−x possesses the lowest charge-transfer resistance (22 Ω) when compared with those of Bi 3 TaO 7 (46 Ω) and MC (84 Ω), indicating its fast charge transfer and enhanced polysulfide redox kinetics, as shown in Figure 5 c [ 31 ].…”