Defect Engineering for Expediting Li–S Chemistry: Strategies, Mechanisms, and Perspectives

Abstract

as well as the cost-effectiveness and environmental-friendliness of sulfur resource. [1][2][3][4][5][6][7][8] However, a suite of troublesome problems, mainly pertaining to sluggish redox kinetics and severe polysulfide (PS) shuttle, has hampered the pathway for pursuing Li-S commercialization. [9][10][11][12][13] For one thing, the conversion from PS to Li 2 S exhibits large energy barriers, which is regarded as the rate-determining step of sulfur reduction reaction (SRR) process. For another, Li 2 S is prone to accumulating at the cathode side, which is not easy to be efficiently dissociated.Recent years have witnessed a burgeoning interest in designing adsorptive and electrocatalytic mediators for effective PS management in Li-S realm, in order to essentially expedite redox kinetics and inhibit "shuttle effect." [14][15][16][17][18][19][20] Although strenuous efforts have been devoted to exploring various types of PS mediators including carbonaceous materials, [21][22][23][24][25] metal oxides/carbides/nitrides/borides/ sulfides/selenides/phosphides, [26][27][28][29][30][31][32][33][34][35][36] and heterostructures, [37][38][39][40][41][42][43][44] their unsatisfactory adsorptive and catalytic behavior caused by insufficient active sites remains a huge barrier for obtaining favorable Li-S chemistry. To circumvent this problem, adjusting the morphology of PS mediators such as reducing their size to nanoscale has been recognized as a promising method to expose more active lattice planes and edge sites. Indeed, a myriad of PS mediators possessing ultrafine nanoparticle and ultrathin nanosheet architecture has been developed to efficiently adsorb sulfur species and catalyze PS conversion. [45][46][47][48][49] Furthermore, optimizing the electronic structure of PS mediator also serves as an appealing approach to boost electrochemical activities. [50][51][52][53][54] Defect engineering, an essential strategy to tailor the atomic distribution and dictate the surface property of nanomaterials, [55][56][57][58][59][60] plays a pivotal role in optimizing the electronic structure and promoting the electrochemical performance of catalysts in various scenarios including hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO 2 RR), and nitrogen reduction reaction (NRR). [61][62][63][64][65][66][67][68][69][70][71][72] Very recently, defect engineering has stimulated a growing attention on PS mediator design in Li-S realm. Benefiting from a collection of compelling functionalities, defective mediator showcases remarkable promise in regulating PS behavior and realizing fast redox chemistry, thereby paving an innovative way toward practical applications of Li-S batteries.Lithium-sulfur (Li-S) batteries have stimulated a burgeoning scientific and industrial interest owing to high energy density and low materials costs. The favorable reaction kinetics of sulfur species is a key prerequisite for pursuing their commercialization. Recent years have ...

P‐Doped NiTe2 with Te‐Vacancies in Lithium–Sulfur Batteries Prevents Shuttling and Promotes Polysulfide Conversion

“…[15,16] Defect engineering (e.g., O-, S-, Se-deficient) can significantly increase catalyst conductivity, supply active sites, improve polysulfide confinement, and increase catalytic activity. [17][18][19][20][21][22][23][24] For example, Chen et al reported selenide defects in a Sb 2 Se 3−x microsphere that exhibited high-conductivity and stable sulfur electrochemistry. [19] Metal-telluride dichalcogenides exhibit metallic properties with high conductivity (e.g., 1.15 × 10 6 S m −1 for NiTe 2 ), relative to sulfide and selenide counterparts (0.55 S m −1 for NiS 2 , 10 S m −1 for NiSe 2 ), and exhibit high electrocatalytic activity.…”

Design a Catalytic Cathode Material with Abundant Oxygen Vacancies to Accelerate the Kinetics of Lean‐Electrolyte Lithium‐Sulfur Batteries

“…Research shows CeÀ TiO 2 maintains distinguished catalysis at high temperatures, [16] so the catalysis of 0.4 CeÀ TiO 2 for polysulfides at elevated temperatures is investigated by the symmetric cells of Li 2 S 6 as Figure S14 shows. For all temperatures, the CV curves of the cells without Li 2 S 6 exhibit capacitive behavior, however, the ones with Li 2 S 6 exhibit a much higher current density, manifesting the 0.4 CeÀ TiO 2 /rGO and TiO 2 /rGO can provide effective catalysis for Li 2 S 6 at elevated temperatures.…”

“…[15] Research also had proved that cation doping in TiO 2À x can improve the adsorption and catalytic activity for polysulfides. [16] Herein, we fabricated the anatase TiO 2 doping by Ce element (Ce-doped TiO 2 ) to induce oxygen vacancies, [17] increasing the catalytic activity of TiO 2 . [18,19] The Ce-doped TiO 2 was served as a strong absorbent and catalyst, and the reduced graphene oxide (rGO) was combined to provide a conductive network and a high specific area for hosting sulfur.…”

High-Index Faceted Nanocrystals as Highly Efficient Bifunctional Electrocatalysts for High-Performance Lithium–Sulfur Batteries

“…However, the commercial application of Li-S batteries is still constrained by many challenges. The inevitable dissolution of lithium polysulfides (LiPSs) intermediates in the electrolytes and the shuttling of LiPSs between the cathode and anode result in low sulfur utilization, swift capacity degradation and the corrosion of lithium anode [9][10][11][12][13][14][15][16]. In addition, the sluggish redox kinetics resulting from insulating sulfur and Li 2 S during discharge/charge cycles limits the efficient conversion of sulfur species, impairing the rate performance and cycling stability of Li-S batteries [17][18][19][20][21][22].…”