High-Entropy and Na-Rich-Designed High-Energy-Density Na 3 V 2 (PO 4 ) 3 /C Cathode

• Published in: ACS nano 2024-12, Vol.18 (52), p.35632-35643
• Main Authors: Ding, Xiang, Yang, Xiaofen, Li, Jie, Yang, Yibing, Liu, Liangwei, Xiao, Yi, Han, Lili
• Format: Article
• Language: English
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/acsnano.4c14284

The Na V (PO ) (NVP) cathode holds the merit of a stable 3D NASICON structure for ultrafast Na diffusion, yet it is still confronted with poor electronic conductivity (10 S cm ) and insufficient energy density (∼370 W h kg ). Herein, a series of high-entropy-doped Na V Zn (GaCrAlIn) (PO ) ( = 0, 0.2, 0.35, and 0.5) cathodes are systematically prepared with an activated V ⇌V high-voltage plateau (4.0 V) and elevated discharge capacity, which is derived from the charge compensation of divalent Zn substituting for trivalent V accompanied by extra Na input to create an Na-rich phase. A range of in situ/ex situ characterization studies and DFT calculations radically verify the charge conservation mechanism, enhanced bulk conductivity, and robust structural stability. Accordingly, in half-cells, the optimized cathode ( = 0.35) is capable of giving a much-improved discharge capacity (126.8 mA h g ), reliable cycling stability (97.4%@5000 cycles@40 C), and a competitive energy density (426.1 W h kg ) at 2.0-4.3 V. Upon reducing the discharge cutoff voltage to 1.4 V, the three-electron reaction (V ⇌V ) is entirely activated with superior stability, delivering an unparalleled capacity of 193.4 mA h g with higher energy density (544.3 W h kg ). Besides, it displays high capacity (126.1 mA h g ) and energy density (417.2 W h kg ) in NVPZGCAI-35//hard carbon full-cells at 1.6-4.1 V. Hence, this pioneering high-entropy and Na-rich strategy is above rubies for developing high-energy-density and high-stability sodium-ion batteries.