Engineering anion defects of ternary V-S-Se layered cathodes for ultrafast zinc ion storage

In this work, a novel stainless-steel (SS) supported lattice-mismatched V-S-Se layered compound (VSySe2_x-SS) with high selenium (Se) vacancy was synthesized by tailoring the molar ratio of S to Se. The difference between the radii of Se and S results in lattice mismatches for a large number of Se vacancies, and the highest vacancy with the ultrafast zinc (Zn) storage performance are achieved by tuning a molar ratio of sulfur (S) to Se. More interestingly, with the introduction of Se vacancies, additional redox peaks of S appear, and creates more masstransport channels as well as active sites for Zn2} toward fast reaction kinetics. Density functional theory (DFT) calculations confirm that the Se defects can also effectively reduce the adsorption energy of Zn2} ions on VS0.5Se2_x-SS for more reversible adsorption/desorption process of Zn2} ions. Consequently, the specific capacity of the VS0.5Se2_x-SS electrode is as high as 188.1 mAh g_ 1 after 70 cycles at 0.6 A g_ 1, while accomplishing an excellent rate capability and satisfactory cycle stability. In addition, an assembled flexible quasi-solid state VS0.5Se2_x-SS//Zn battery also display good cycle stability, excellent electrochemical performance, and good environmental adaptability under different malignant environments including bending, soaking, hammering, weighing, washing and cutting. This work demonstrates a facile approach for electrode modifications used in Zn2} ion batteries, holding great promise for practical applications and shedding lights on fundamentals of defects effects on battery performance.

Automated summary

A novel stainless-steel supported lattice-mismatched V-S-Se layered compound with high selenium vacancy was synthesized by adjusting the molar ratio of sulfur to selenium. The introduction of selenium vacancies created additional redox peaks of sulfur, providing more mass transport channels and active sites for zinc ions. The specific capacity and cycle stability of the electrode were significantly improved, demonstrating great potential for practical applications and providing insights into the effects of defects on battery performance.