Oh, Gwangeon Kim, Jun Tae Shin, Heesung Kansara, Shivam Kang, Hyokyeong Son, Jun Pyo Jung, Yoon Seok Bresser, Dominic Li, Shiyu Jung, Hun-Gi Hwang, Jang-Yeon 2025-09-30T07:02:46Z 2025-09-30T07:02:46Z 2025-09-30 2025-11 https://pubs.kist.re.kr/handle/201004/153286 O3-type layered sodium chromium oxide (O3-NaCrO2) is a promising cathode material for cost-effective and practical sodium-ion batteries (SIBs). However, achieving a high energy density in SIBs with NaCrO2 as the cathode remains challenging owing to chromium migration and irreversible phase transition at voltages above 3.6 V (vs Na/Na+). Herein, a substantially improved high-voltage stability of O3-NaCrO2 (O3-NCO) as a cathode through the implementation of high-valent Nb5+ substitution strategies is reported. The strong interaction between Nb5+ and O2− ions alleviates structural stress during repeated charge and discharge processes. The introduced Nb5+ enhances the disorder in the transition metal layer and structural stability, increasing the reversibility by suppressing Cr disproportionation reactions and irreversible Cr migration. Additionally, Nb5+ creates Na+/vacancies in the Na layer owing to charge compensation, thereby facilitating the Na-ion diffusion kinetics. Consequently, 3 mol% of Nb-substituted O3-Na0.94Cr0.97Nb0.03O2 cathode demonstrates superior reversible capacity, cycle life, and rate capability. Furthermore, the high-valent Nb substitution strategy improves water stability and shows good compatibility with all-solid-state battery systems, highlighting its excellent practical applicability. English WILEY Introduction of High-Valent Metal in Transition Metal Layer as a Structural Reinforcement for a O3-Type NaCrO2 Sodium-Ion Battery Cathode Article 10.1002/sstr.202500400 1 Small Structures, v.6, no.11 Small Structures 6 11 Y scie scopus 001570580400001 2-s2.0-105015619199 Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Chemistry Science & Technology - Other Topics Materials Science Article HIGH-ENERGY STORAGE SURFACE TOOL high power high-valent metal substitution high voltages layered-type cathode Na-ion batteries