Enabling One‐Step De‐Sodiation of Na<sub>4</sub>MnV(PO<sub>4</sub>)<sub>3</sub> Cathode via Regulating Coordination Environment for High‐Power and Long‐Lasting Sodium‐Ion Batteries
Can Chen, Liqun Wang, Zhihao Deng, Xueling Kong, Tianyi Zhang, Qinqin Yu, Zuyong Wang, Peining Zhu, Yuan‐Li Ding
Abstract
Abstract Na 4 MnV(PO 4 ) 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 (Mn 3+ /Mn 2+ ) besides the voltage plateau of 3.4 V (V 4+ /V 3+ ), lower cost, and environmental benign compared to Na 3 V 2 (PO 4 ) 3 . However, such cathode still suffers from sluggish intrinsic Na + diffusion kinetics and the Jahn‐Teller distortion of Mn 3+ , 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 Zr 4+ and K + /Ca 2+ into Mn and Na sites, respectively. Based on theoretical calculations and electrochemical evaluation, the obtained Na 3.3 K 0.1 Ca 0.1 Mn 0.8 VZr 0.2 (PO 4 ) 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).