Ding Xiang, Yang Xiaofen, Li Jie, Yang Yibing, Liu Liangwei, Xiao Yi, Han Lili
College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, China.
Fujian Provincial Key Laboratory of Advanced Inorganic Oxygenated Materials, College of Chemistry, Fuzhou University, Fuzhou 350108, China.
ACS Nano. 2024 Dec 31;18(52):35632-35643. doi: 10.1021/acsnano.4c14284. Epub 2024 Dec 19.
The NaV(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 NaVZn(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.
NaV(PO)（NVP）阴极具有稳定的3D NASICON结构，有利于超快的Na扩散，但它仍面临电子传导性差（10 S cm）和能量密度不足（约370 W h kg）的问题。在此，系统制备了一系列高熵掺杂的NaVZn(GaCrAlIn)(PO)（ = 0、0.2、0.35和0.5）阴极，其具有激活的V⇌V高压平台（4.0 V）和提高的放电容量，这源于二价Zn取代三价V的电荷补偿以及额外的Na输入以形成富Na相。一系列原位/非原位表征研究和DFT计算从根本上验证了电荷守恒机制、增强的体相电导率和稳健的结构稳定性。因此，在半电池中，优化后的阴极（ = 0.35）能够在2.0 - 4.3 V下提供显著提高的放电容量（126.8 mA h g）、可靠的循环稳定性（5000次循环@40 C时为97.4%）和有竞争力的能量密度（426.1 W h kg）。将放电截止电压降低到1.4 V时，三电子反应（V⇌V）被完全激活，具有优异的稳定性，提供了193.4 mA h g的无与伦比的容量和更高的能量密度（544.3 W h kg）。此外，在NVPZGCAI - 35//硬碳全电池中，在1.6 - 4.1 V下它显示出高容量（126.1 mA h g）和能量密度（417.2 W h kg）。因此，这种开创性的高熵和富Na策略对于开发高能量密度和高稳定性的钠离子电池来说价值连城。
