Enabling One‐Step De‐Sodiation of Na4MnV(PO4)3 Cathode via Regulating Coordination Environment for High‐Power and Long‐Lasting Sodium‐Ion Batteries

• Published in: Advanced functional materials Vol. 35; no. 14
• Main Authors: Chen, Can, Wang, Liqun, Deng, Zhihao, Kong, Xueling, Zhang, Tianyi, Yu, Qinqin, Wang, Zuyong, Zhu, Peining, Ding, Yuan‐Li
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 03.04.2025
• Subjects: Batteries; Calcium ions; Cathodes; Chemical diffusion; Coordination; Diffusion coefficient; Diffusion rate; Distortion; Electric potential; Electrochemical analysis; Electrons; Jahn‐Teller effect; one‐step de‐sodiation; polyanionic cathode; Room temperature; Sodium; Sodium-ion batteries; Voltage
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202418642

Na4MnV(PO4)3 (NMVP) is considered as a promising cathode candidate for sodium‐ion batteries (SIBs) because it possesses a higher voltage plateau of 3.6 V (Mn3+/Mn2+) besides the voltage plateau of 3.4 V (V4+/V3+), lower cost, and environmental benign compared to Na3V2(PO4)3. However, such cathode still suffers from sluggish intrinsic Na+ diffusion kinetics and the Jahn‐Teller distortion of Mn3+, leading to low capacity and poor cycling performance. Particularly, the second‐step Na+ de‐sodiation in NMVP is the rate‐determining step owing to a lower chemical diffusion coefficient with one order of magnitude than that of the first‐step counterpart. To address these issues, a coordination environment regulation strategy is reported to develop a one‐step de‐sodiation NMVP cathode via introducing Zr4+ and K+/Ca2+ into Mn and Na sites, respectively. Based on theoretical calculations and electrochemical evaluation, the obtained Na3.3K0.1Ca0.1Mn0.8VZr0.2(PO4)3 exhibits much enhanced Na+ diffusion and efficiently inhibits the Jahn‐Teller distortion. Importantly, such modification significantly facilitates the second‐step Na+ diffusion of NMVP, realizing one‐step de‐sodiation. When employed as a cathode for SIBs, such cathode shows a specific capacity of 73 mAh g−1 (15 C), and capacity retentions of 92.7% after 3000 cycles (at 10 C, room temperature), and 72.6% after 1000 cycles (1 C, 50 °C). One‐step de‐sodiation of Na4MnV(PO4)3 is achieved successfully via regulating the local coordination environment of transition metal sites using Zr4+ since such cathode suffers from severely limited Na+ diffusion kinetics in the second‐step de‐sodiation (rate‐determining step). Moreover, the Jahn‐Teller distortion is substantially inhibited, leading to much‐enhanced cycling stability at both room temperature and elevated temperature.