Dynamic Lock‐And‐Release Mechanism Enables Reduced Δ G at Low Temperatures for High‐Performance Polyanionic Cathode in Sodium‐Ion Batteries

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Abstract
Low‐temperature synthesis of polyanionic cathodes for sodium‐ion batteries is highly desirable but often plagued by prolonged reaction times and suboptimal crystallinity. To address these challenges, a novel self‐adaptive coordination field regulation (SACFR) strategy based on a dynamic lock‐and‐release (DLR) mechanism is introduced. Specifically, urea is used as a DLR carrier during synthesis, which dynamically “locks” and “releases” vanadium ions for controlled release, simultaneously “locking” H + ions to enhance phosphate group release, thereby creating a self‐adaptive coordination field that can intelligently respond to real‐time demands of the reaction system. This dynamic coordination behavior contributes to both an improvement in reaction kinetics and a significant reduction in Gibbs free energy change ( ΔG ). As a result, the kinetic efficiency and thermodynamic spontaneity of the reaction are greatly enhanced, enabling the efficient synthesis of high‐crystalline Na 3 V 2 O 2 (PO 4 ) 2 F (NVOPF) at 90 °C within just 3 hours. The as‐prepared NVOPF cathode exhibits exceptional rate performance and ultra‐stable cycling stability across a broad temperature range. Furthermore, the successful kilogram‐scale synthesis underscores the practical potential of the innovative strategy. This work pioneers the regulation of coordination field chemistry for polyanionic cathode synthesis, providing transformative insights into material design.
Funding Information
  • National Natural Science Foundation of China (22279009)
  • National Natural Science Foundation of China (22379015)
  • National Natural Science Foundation of China (22005033)
  • Beijing Institute of Technology Research Fund Program for Young Scholars (XSQD‐202108005)

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