Youcun Bai,Heng Zhang,Bin Xiang,Xinyue Liang,Jiangyu Hao,Chong Zhu,Lijin Yan
As a typical transition-metal dichalcogenides, vanadium diselenide (VSe2) is a promising electrode material for aqueous zinc-ion batteries due to its metallic characteristics and excellent electronic conductivity. In this work, we propose a strategy of hydrothermal reduction synthesis of stainless-steel (SS)-supported VSe2 nanosheets with defect (VSe2–x-SS), thereby further improving the conductivity and activity of VSe2–x-SS. Density functional theory calculations confirmed that Se defect can adjust the adsorption energy of Zn2+ ions. This means that the adsorption/desorption process of Zn2+ ions on VSe2–x-SS is more reversible than that on pure SS-supported VSe2 (VSe2-SS). As a result, the Zn//VSe2–x-SS battery showed more excellent electrochemical performance than Zn//VSe2-SS. The VSe2–x-SS electrode shows a good specific capacity of 265.2 mA h g–1 (0.2 A g–1 after 150 cycles), satisfactory rate performance, and impressive cyclic stability. In addition, we also have explored the energy-storage mechanism of Zn2+ ions in this VSe2–x-SS electrode material. This study provides an effective strategy for the rational design of electrode materials for electrochemical energy-storage devices.
The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPSs) represent the main obstructions to the practical application of lithium–sulfur (Li–S) batteries. Herein, an anion-deficient design of antimony selenide (Sb 2 Se 3− x ) is developed to establish a multifunctional LiPS barrier toward the inhibition of polysulfide shuttling and enhancement of battery performance. The defect chemistry in the as-developed Sb 2 Se 3− x promotes the intrinsic conductivity, strengthens the chemical affinity to LiPSs, and catalyzes the sulfur electrochemical conversion, which are verified by a series of computational and experimental results. Attributed to these unique superiorities, the obtained LiPS barrier efficiently promotes and stabilizes the sulfur electrochemistry, thus enabling excellent Li–S battery performance, e.g., outstanding cyclability over 500 cycles at 1.0 C with a minimum capacity fading rate of 0.027% per cycle, a superb rate capability up to 8.0 C, and a high areal capacity of 7.46 mAh cm −2 under raised sulfur loading. This work offers a defect engineering strategy toward fast and durable sulfur electrochemistry, holding great promise in developing practically viable Li–S batteries as well as enlightening the material design of related energy storage and conversion systems.
Due to their environmental friendliness, low cost, and versatility in applications, flexible Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells have garnered significant attention in recent years. However, the lack of alkali metal elements in the flexible substrate has posed a challenge to the advancement of flexible CZTSSe solar cells. In this study, a post-treatment strategy is proposed involving Rb ions to simultaneously regulate the surface properties of the CZTSSe film and the reactions during the CdS chemical bath deposition (CBD) process. Material and chemical characterization results confirm that Rb ions effectively passivate the detrimental Se 0 defect, leading to a more active surface for the CdS epitaxial growth. Additionally, the coordination between Rb ions and thiourea in the CBD solution improves the ion-by-ion deposition of the CdS layer. These beneficial effects significantly improve the heterojunction interface and consequently enable the flexible CZTSSe solar cell to achieve a record total-area efficiency of 12.84% and excellent bending performance. Overall, the heterojunction interface regulation strategy employed in this work, along with the obtained remarkable results, offer promising prospects for the development of flexible CZTSSe solar cells.
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