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

Abstract 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 Na_3.3K_0.1Ca_0.1Mn_0.8VZr_0.2(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).