Electrochromic materials capable of broadband optical modulation are highly attractive for adaptive photonic technologies. Oxygen-deficient tungsten oxide (W₁₈O₄₉) has emerged as a promising electrochromic material owing to its abundant oxygen vacancies and high electronic conductivity. However, despite its considerable potential, the relationship between ion-storage mechanisms and reversible electrochromic behavior remains poorly understood, limiting the rational design of high-performance electrochromic systems. Here, W₁₈O₄₉ nanowires were systematically investigated to elucidate the influence of ion-storage mechanisms on electrochromic performance. By comparing Li⁺- and TBA⁺-based electrolytes, their distinct electrochemical behaviors and ion-storage pathways were identified. The results reveal that efficient bulk Li⁺ intercalation enables reversible electrochromic switching, whereas the bulky TBA⁺ ions are mainly involved in surface-confined redox reactions, resulting in limited electrochromic activity. These findings demonstrate that the ion-storage mechanism plays a decisive role in governing the electrochromic response of oxygen-deficient tungsten oxides. This work provides mechanistic insights into the electrochromic behavior of W₁₈O₄₉ nanowires and offers a useful strategy for the rational design of next-generation flexible electrochromic materials and devices.
 

W₁₈O₄₉ Nanowires,Oxygen-Deficient