A modified sodium iron pyrophosphate cathode material and its preparation method and application

By adopting a multi-layer core-shell structure and gradient doping of NaFePO4 in the sodium iron pyrophosphate positive electrode material, the problems of low discharge capacity and poor cycle stability of NFPP materials were solved, and stable Na+ insertion/extraction at high voltage and excellent cycle performance were achieved.

CN119943909BActive Publication Date: 2025-09-30BEI JING XI BEI DONG LI KE JI YOU XIAN GONG SI
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Patent Information

Application Number
CN202510111061.3
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-01-23
Publication Date
2025-09-30
Estimated Expiration
2045-01-23

AI Technical Summary

Technical Problem

Existing sodium ferric pyrophosphate (NFPP) cathode materials have the problems of low discharge specific capacity and poor cycle stability.

Method used

A modified sodium iron pyrophosphate cathode material with a multi-layer core-shell structure is adopted. A gradient coating layer is formed by gradient doping NaFePO4, and multiple shell layers are constructed to improve the conductivity and structural stability, including a Na4Fe3(PO4)2P2O7 core, a Na4+xFe3+x(PO4)2+xP2O7 middle coating layer and a Na4+yFe3+y(PO4)2+yP2O7 outer coating layer.

Benefits of technology

The discharge capacity and rate performance of the modified sodium iron pyrophosphate positive electrode material are significantly improved, and the cycle performance is enhanced, especially maintaining stable Na+ insertion/extraction transition and phase change at high voltage, thereby improving the cycle life at high temperature.

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Abstract

The present invention relates to the technical field of sodium ion battery positive electrode materials, and in particular to a modified sodium ferric pyrophosphate positive electrode material and its preparation method and application. The modified sodium ferric pyrophosphate positive electrode material comprises a Na4Fe3(PO4)2P2O7 core and Na 4+x Fe 3+x (PO4) 2+x P2O7 intermediate coating and Na 4+y Fe 3+y (PO4) 2+y P2O7 outer coating layer, wherein 0.1≤x<0.5, 0.1<y≤0.5, and y-x≥0.1. The modified sodium ferric pyrophosphate positive electrode material provided by the present invention has a multi-level core-shell structure. The gradient coating layer is formed by gradient doping with NaFePO4, which effectively improves the conductivity and structural stability of the modified sodium ferric pyrophosphate positive electrode material, thereby having a higher discharge capacity and excellent rate performance and cycle performance.
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