Presentation Title: Niobium Doping Regulates Local Structure of NFPP to Suppress Inactive Phase Formation and Enhance Working Voltage

Abstract: 

     Sodium-ion batteries hold great promise for large-scale energy storage owing to the abundant reserves and low cost of sodium resources. Among the emerging cathode candidates, Na₄Fe₃(PO₄)₂P₂O₇ (NFPP) stands out as a competitive polyanionic material due to its high theoretical capacity and environmental friendliness. However, the unavoidable formation of the electrochemically inactive maricite-NaFePO₄ (NFP) phase during synthesis severely restricts the practical capacity. Additionally, the inherently poor electronic conductivity and sluggish ion diffusion kinetics limit the rate capability of NFPP. To address these challenges, this report introduces niobium (Nb) doping to regulate the local structure of NFPP, yielding a Nb-modified NFPP cathode material. Combined first-principles calculations and in situ X-ray diffraction analyses reveal that Nb preferentially occupies the Fe3 site, which effectively disrupts the edge-sharing connectivity of FeO₆ octahedra, thereby fundamentally suppressing the formation of the NFP impurity phase. Moreover, Nb substitution reduces the proportion of corner-sharing FeO₆ structural units, altering the local coordination environment for sodium ions and consequently elevating the average working voltage. As a result, the Nb-doped NFPP material delivers a remarkably high specific capacity, outstanding rate performance, and significantly enhanced cycling stability. By demonstrating a spray-drying followed by moderate-temperature calcination process, this work provides a scalable and cost-effective pathway for the development of high-performance NFPP cathodes for sodium-ion batteries, marking a significant step forward in expanding the technological frontier of niobium-based energy storage materials.

Biography: 

      Dr. Yong Jiang is a Professor and Ph.D. supervisor at Shanghai University. He has long been dedicated to research in the field of advanced energy batteries, with a primary focus on the fundamental research and application development of electrochemical functional materials and energy storage devices, including high-energy-density lithium/sodium-ion batteries, solid-state batteries, and lithium-sulfur batteries. He has led a variety of research projects, including the General Program and Young Scientists Fund of the National Natural Science Foundation of China (NSFC), the Major Project of Shanghai's "Science and Technology Innovation Action Plan," the Technical Standard Special Project of the Shanghai Municipal Science and Technology Commission, and major industry-university cooperation projects. He has published over 150 SCI-indexed research papers in prestigious international journals such as Advanced Materials, Angewandte Chemie International Edition, Advanced Energy Materials, Advanced Functional Materials, and Energy Storage Materials, among which more than 10 are ESI Highly Cited Papers. He is committed to fostering industry-academic partnerships and possesses extensive experience in translating research finding into practical industrial applications.