Mn-Rich Phosphate Cathodes for Na-Ion Batteries with Superior Rate Performance

• Published in: ACS energy letters Vol. 7; no. 1; pp. 97 - 107
• Main Authors: Xu, Chunliu, Xiao, Ruijuan, Zhao, Junmei, Ding, Feixiang, Yang, Yang, Rong, Xiaohui, Guo, Xiaodong, Yang, Chao, Liu, Huizhou, Zhong, Benhe, Hu, Yong-Sheng
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.01.2022
• ISSN: 2380-8195; 2380-8195
• DOI: 10.1021/acsenergylett.1c02107

A Mn-based NASICON-type Na4VMn­(PO4)3 cathode is considered to be one of the most promising substitutions for Na3V2(PO4)3 due to the huge abundance and appropriate redox potential from Mn. However, the current Na4VMn­(PO4)3/C cathode still delivers a limited electrochemical performance due to the sluggish kinetics and negative structural degradation caused by the Mn in the structure. Herein, a selective replacement of vanadium rather than manganese in the Na4VMn­(PO4)3 system was developed to fully utilize the manganese element and enhance the structural stability. Both experimental and calculation results affirmed that the Al-substituted Na4V0.8Al0.2Mn­(PO4)3 cathode shows favorable Na+ kinetics and structure stability. The resulting Na4V0.8Al0.2Mn­(PO4)3 reveals a discharge capacity of ∼84 mA h g–1 at 40 C and renders a capacity retention of 92% after cycling 1000 times at 5 C. Inspired by the availability of Al dopants, we also demonstrated the Al-doped Mn-richer Na4.2V0.6Al0.2Mn1.2(PO4)3 to be a viable candidate for Mn-rich phosphate cathodes.