@article{Liu2024, 
author = {Zhaolu Liu and Yongjie Cao and Ning Wang and Hui Yang and Hao Zhang and Xinyue Xu and Nan Wang and Jie Xu and Yao Liu and Junxi Zhang and Yongyao Xia},
title = {Unlocking iron-based mixed-phosphate cathode for sodium-ion batteries through off-stoichiometry},
year = {2024},
journal = {Nano Research},
volume = {17},
number = {9},
pages = {8119-8125},
keywords = {sodium-ion batteries, cathode material, iron-based mixed-phosphates, off-stoichiometric},
url = {https://www.sciopen.com/article/10.1007/s12274-024-6804-1},
doi = {10.1007/s12274-024-6804-1},
abstract = {The off-stoichiometric iron-based phosphate (Na3.12Fe2.44(P2O7)2, denoted as Na3.12) as a low cost and high structure stability cathode material has been widely studied for sodium-ion batteries (SIBs). However, the lower theoretical specific capacity (117 mAh·g−1) has seriously limited its practical application. In this work, we incorporate varying proportion of sodium-iron phosphate (NaFePO4) into the Na3.12 to form a series of new high specific capacity mixed-phosphates Na3.12+xFe2.44+x(P2O7)2(PO4)x cathode materials for SIBs. After optimizing the introduction amount of NaFePO4 into Na3.12, the practical reversible of Na3.12+xFe2.44+x(P2O7)2(PO4)x increased from 92 to 125.2 mAh·g−1. The nano-size Na5.12Fe4.44(P2O7)2(PO4)2 cathode material shows a reversible specific capacity of 125.2 mAh·g−1 at 0.1 C in SIBs. Even at 60 C, it still exhibits a reversible specific capacity of 93.3 mAh·g−1 and keeps a capacity retention ratio of 87% after 3000 cycles at 20 C. Thereby, we present a novel approach to design a series of off-stoichiometric mixed-phosphates cathode materials for SIBs.}
}