A High‐Energy NASICON‐Type Cathode Material for Na‐Ion Batteries
Jingyang Wang, Yan Wang, Dong‐Hwa Seo, Tan Shi, Shouping Chen, Yaosen Tian, Haegyeom Kim, Gerbrand Ceder
Abstract
Abstract Over the last decade, Na‐ion batteries have been extensively studied as low‐cost alternatives to Li‐ion batteries for large‐scale grid storage applications; however, the development of high‐energy positive electrodes remains a major challenge. Materials with a polyanionic framework, such as Na superionic conductor (NASICON)‐structured cathodes with formula Na x M 2 (PO 4 ) 3 , have attracted considerable attention because of their stable 3D crystal structure and high operating potential. Herein, a novel NASICON‐type compound, Na 4 MnCr(PO 4 ) 3 , is reported as a promising cathode material for Na‐ion batteries that deliver a high specific capacity of 130 mAh g −1 during discharge utilizing high‐voltage Mn 2+/3+ (3.5 V), Mn 3+/4+ (4.0 V), and Cr 3+/4+ (4.35 V) transition metal redox. In addition, Na 4 MnCr(PO 4 ) 3 exhibits a high rate capability (97 mAh g −1 at 5 C ) and excellent all‐temperature performance. In situ X‐ray diffraction and synchrotron X‐ray diffraction analyses reveal reversible structural evolution for both charge and discharge.