Long Tao, Li Ruotong, Kong Xueling, Feng Bin, Wang Kairong, Wang Yulei, Chen Can, Wang Yaping, Yu Qinqin, Wu Meng, Ding Yuan-Li
College of Materials Science and Engineering, Hunan University, Changsha, 410082, China.
College of Materials and Chemical Engineering, Pingxiang University, Pingxiang, 337055, China.
Small. 2025 Feb;21(7):e2410456. doi: 10.1002/smll.202410456. Epub 2025 Jan 10.
Mn-containing sodium superionic conductor (NASICON) compounds have shown considerable potential as cathode for sodium-ion batteries (SIBs) owing to higher working voltage (V/V: 3.9 V), lower cost, and lower toxicity compared to full vanadium-based NASICON NaV(PO). Taking NaVMn(PO) (NVMP) as an example, its practical application is still restricted by poor electronic conductivity, sluggish intrinsic Na diffusion, and poor high-voltage stability. In this work, a high entropy strategy is proposed to develop NaVMn(Cr, Fe, Co, Ni, Zr)(PO) (HE-NVMP) cathode for not only enabling more and rapid Na migration but also significantly improving deep desodiation stability. Based on theoretical calculations and experimental findings, such high entropy modification can efficiently alter the coordination environments of both V/Mn and Na sites for reducing Na diffusion energy barrier, increasing the occupancy of Na at Na(2) sites, and consolidating the structure stability. Thus, the obtained HE-NVMP delivers superior high-rate capability (91.7 mAh g) up to 50 C and excellent cycling performance (capacity retention: 81.2%) after 10 000 cycles at 20 C at the cutoff voltage of 4.1 V. More importantly, such cathode also exhibits superior sodium storage properties at a higher cutoff voltage (4.5 V) with electrochemical polarization with 75% reduction at 1 C and higher capacity retention of 80.3% after 2000 cycles at 20 C compared to pristine counterpart, indicating a great potential for practical rechargeable batteries with excellent overcharge resistance capability.
含锰的钠超离子导体（NASICON）化合物作为钠离子电池（SIBs）的正极显示出了巨大的潜力，这是因为与全钒基NASICON NaV(PO)相比，其工作电压更高（V/V：3.9 V）、成本更低且毒性更低。以NaVMn(PO)（NVMP）为例，其实际应用仍受到电子导电性差、本征钠扩散缓慢以及高压稳定性差的限制。在这项工作中，提出了一种高熵策略来开发NaVMn(Cr, Fe, Co, Ni, Zr)(PO)（HE-NVMP）正极，不仅能使更多且更快的钠迁移，还能显著提高深度脱钠稳定性。基于理论计算和实验结果，这种高熵改性可以有效地改变V/Mn和Na位点的配位环境，以降低钠扩散能垒，增加Na在Na(2)位点的占有率，并巩固结构稳定性。因此，所获得的HE-NVMP在高达50 C的电流密度下具有优异的高倍率性能（91.7 mAh g），在4.1 V的截止电压下于20 C循环10000次后具有出色的循环性能（容量保持率：81.2%）。更重要的是，与原始材料相比，这种正极在更高的截止电压（4.5 V）下也表现出优异的储钠性能，在1 C时电化学极化降低75%，在20 C循环2000次后容量保持率更高，为80.3%，这表明其在具有优异过充抗性能力的实用可充电电池方面具有巨大潜力。
