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1.
Adv Mater ; : e2105951, 2021 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-34617348

RESUMO

Zn metal anode has garnered growing scientific and industrial interest owing to its appropriate redox potential, low cost, and high safety. Nevertheless, the instability of Zn anode caused by dendrite formation, hydrogen evolution, and side reactions has greatly hampered its commercialization. Herein, an in situ grown ZnSe overlayer is crafted over one side of commercial Zn foil via chemical vapor deposition in a scalable manner, aiming to achieve optimized electrolyte/Zn interfaces with large-scale viability. Impressively, thus-derived ZnSe coating functions as a cultivator to guide oriented growth of Zn (002) plane at the infancy stage of stripping/plating cycles, thereby inhibiting the formation of Zn dendrites and the occurrence of side reactions. As a result, high cyclic stability (1530 h at 1.0 mA cm-2 /1.0 mAh cm-2 ; 172 h at 30.0 mA cm-2 /10.0 mAh cm-2 ) in symmetric cells is harvested. Meanwhile, when paired with V2 O5 based cathode, assembled full cell achieves an outstanding capacity (194.5 mAh g-1 ) and elongated lifespan (a capacity retention of 84% after 1000 cycles) at 5.0 A g-1 . The reversible Zn anode enabled by the interfacial manipulation strategy via ZnSe cultivator is anticipated to satisfy the demand of commercial use.

2.
ACS Nano ; 15(9): 14105-14115, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34351143

RESUMO

Although lithium-sulfur (Li-S) batteries have long been touted as next-generation energy storage devices, the rampant dendrite growth at the anode side and sluggish redox kinetics at the cathode side drastically impede their practical application. Herein, a dual-functional fibrous skeleton implanted with single-atom Co-Nx dispersion is devised as an advanced modificator to realize concurrent regulation of both electrodes. The rational integration of single-atomic Co-Nx sites could convert the fibrous carbon skeleton from lithiophobic to lithiophilic, helping assuage the dendritic formation for the Li anode. Meanwhile, the favorable electrocatalytic activity from the Co-Nx species affording a lightweight feature effectively enables expedited bidirectional conversion kinetics of sulfur electrochemistry, thereby inhibiting the polysulfide shuttle. Moreover, the interconnected porous framework endows the entire skeleton with good mechanical robustness and fast electron/ion transportation. Benefiting from the synergistic effects between atomically dispersed Co-Nx sites and three-dimensional conductive networks, the integrated Li-S full batteries can achieve a reversible areal capacity (>7.0 mAh cm-2) at a sulfur loading of 6.9 mg cm-2. This work might be beneficial to the development of practically viable Li-S batteries harnessing single-atom mediators.

3.
Angew Chem Int Ed Engl ; 60(46): 24558-24565, 2021 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-34435420

RESUMO

Witnessing compositional evolution and identifying the catalytically active moiety of electrocatalysts is of paramount importance in Li-S chemistry. Nevertheless, this field remains elusive. We report the scalable salt-templated synthesis of Se-vacancy-incorporated MoSe2 architecture (SeVs-MoSe2 ) and reveal the phase evolution of the defective precatalyst in working Li-S batteries. The interaction between lithium polysulfides and SeVs-MoSe2 is probed to induce the transformation from SeVs-MoSe2 to MoSeS. Furthermore, operando Raman spectroscopy and ex situ X-ray diffraction measurements in combination with theoretical simulations verify that the effectual MoSeS catalyst could help promote conversion of Li2 S2 to Li2 S, thereby boosting the capacity performance. The Li-S battery accordingly exhibits a satisfactory rate and cycling capability even with and elevated sulfur loading and lean electrolyte conditions (7.67 mg cm-2 ; 4.0 µL mg-1 S ). This work elucidates the design strategies and catalytic mechanisms of efficient electrocatalysts bearing defects.

4.
Adv Mater ; 33(43): e2103050, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34463382

RESUMO

Lithium-sulfur (Li-S) batteries are promising candidates for next-generation energy storage, yet they are plagued by the notorious polysulfide shuttle effect and sluggish redox kinetics. While rationally designed redox mediators can facilitate polysulfide conversion, favorable bidirectional sulfur electrocatalysis remains a formidable challenge. Herein, selective dual-defect engineering (i.e., introducing both N-doping and Se-vacancies) of a common MoSe2 electrocatalyst is used to manipulate the bidirectional Li2 S redox. Systematic theoretical prediction and detailed electrokinetic analysis reveal the selective electrocatalytic effect of the two types of defects, thereby achieving a deeper mechanistic understanding of the bidirectional sulfur electrochemistry. The Li-S battery using this electrocatalyst exhibits excellent cyclability, with a low capacity decay rate of 0.04% per cycle over 1000 cycles at 2.0 C. More impressively, the potential for practical applications is highlighted by a high areal capacity (7.3 mAh cm-2 ) and the construction of a flexible pouch cell. Such selective electrocatalysis created by dual-defect engineering is an appealing approach toward working Li-S systems.

5.
ACS Nano ; 14(11): 16073-16084, 2020 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-33156985

RESUMO

The Li-S battery has emerged as a promising next-generation system for advanced energy storage. Notwithstanding the recent progress, the problematic polysulfide shuttling, retarded sulfur redox, and low output of volumetric capacity remain daunting challenges toward its practicability. In response, this work demonstrates herein a universal approach to in situ craft MOx-MXene (M: Ti, V, and Nb) heterostructures as heavy and multifunctional hosts to harvest good battery performances with synchronous polysulfide immobilization and conversion. Theoretical calculations indicate that the in situ implanted oxides boost the reaction kinetics of polysulfide transformation without affecting the intrinsic conductivity of MXene. As a result, the representative VOx-V2C/S electrode enables a high volumetric capacity (offering 1645.98 mAh cm-3 at 0.2 C) and cycling stability (retaining 631.17 mAh cm-3 after 1500 cycles at 2.0 C with a capacity decay of 0.03% per cycle). More encouragingly, 3D-printed sulfur electrodes harnessing VOx-V2C hosts readily harvest an areal capacity of 9.74 mAh cm-2 at 0.05 C under an elevated sulfur loading of 10.78 mg cm-2, holding promise for the development of practically viable Li-S batteries.

6.
Adv Mater ; 32(50): e2005967, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33179368

RESUMO

Lithium-sulfur (Li-S) batteries have heretofore attracted tremendous interest due to low cost and high energy density. In this realm, both the severe shuttling of polysulfide and the uncontrollable growth of dendritic lithium have greatly hindered their commercial viability. Recent years have witnessed the rapid development of rational approaches to simultaneously regulate polysulfide behaviors and restrain lithium dendritic growth. Nevertheless, the major obstacles for high-performance Li-S batteries still lie in little knowledge of bifunctional material candidates and inadequate explorations of advanced technologies for customizable devices. Herein, a "two-in-one" strategy is put forward to elaborate V8 C7 -VO2 heterostructure scaffolds via the 3D printing (3DP) technique as dual-effective polysulfide immobilizer and lithium dendrite inhibitor for Li-S batteries. A thus-derived 3DP-V8 C7 -VO2 /S electrode demostrates excellent rate capability (643.5 mAh g-1 at 6.0 C) and favorable cycling stability (a capacity decay of 0.061% per cycle at 4.0 C after 900 cycles). Importantly, the integrated Li-S battery harnessing both 3DP hosts realizes high areal capacity under high sulfur loadings (7.36 mAh cm-2 at a sulfur loading of 9.2 mg cm-2 ). This work offers insight into solving the concurrent challenges for both S cathode and Li anode throughout 3DP.

7.
ACS Nano ; 14(9): 11929-11938, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32790327

RESUMO

Electrocatalysts remain vitally important for the rational management of intermediate polysulfides (LiPSs) in the realm of Li-S batteries. In terms of transition-metal-based candidates, in situ evolution of electrocatalysts in the course of an electrochemical process has been acknowledged; nevertheless, consensus has not yet been reached on their real functional states as well as catalytic mechanisms. Herein, we report an all-chemical vapor deposition design of the defective vanadium diselenide (VSe2)-vertical graphene (VG) heterostructure on carbon cloth (CC) targeting a high-performance sulfur host. The electrochemistry induces the sulfurization of VSe2 to VS2 at Se vacancy sites, which propels the adsorption and conversion of LiPSs. Accordingly, the VSe2-VG@CC/S electrode harvests an excellent cycling stability at 5.0 C with a capacity decay of only 0.039% per cycle over 800 cycles, accompanied by a high areal capacity of 4.9 mAh cm-2 under an elevated sulfur loading of 9.6 mg cm-2. Theoretical simulation combined with operando characterizations reveals the key role played by the Se vacancy with respect to the electrocatalyst evolution and LiPS regulation. This work offers insight into the rational design of heterostructure sulfur hosts throughout defect engineering.

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