A cerium vanadate/S heterostructure for a long-life zinc-ion battery: efficient electron transfer by the anchored sulfur

Abstract

Ce_0.25V₂O₅(H₂O)·H₂O (CeVO) or Ce_0.3V₂O₅(H₂O)·H₂O/S (CeVS) was synthesized based on a facile one-step hydrothermal reaction of Ce(SO₄)₂ and V₂O₅ or VS₂. Rietveld refinement of CeVO unveils the intercalation of Ce ions into layered V₂O₅ with a large (001) lattice spacing of 12.1 Å. CeVS is a CeVO/S heterostructure, which originates from the hydrothermal transformation of VS₂ → V₂O₅ + S₈ and the simultaneous intercalation of Ce ions. The pre-intercalation of Ce ions leads to a Zn²⁺ migration barrier of 1.32 eV in CeVO, and CeVO shows a capacity of 376 mA h g⁻¹ at 0.1 A g⁻¹. However, CeVS exhibits a higher capacity (438 mA h g⁻¹) and an ultralong lifespan with a capacity retention of 100% over 10 500 cycles at 5 A g⁻¹. The conversion between S⁰ and vanadium sulfide (yS⁰ + 2e⁻ ↔ S_y²⁻) in CeVS during the discharge and charge process can not only provide extra capacity, but also maintain the crystallinity and stability of CeVO, in which S transfers electrons like an electron shuttle to avoid the structural collapse and fast capacity fading of CeVO.