Hunan Provincial Key Laboratory of Chemical Power Sources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
Hunan Provincial Key Laboratory of Water Treatment Functional Materials, Hunan Provincial Key Laboratory for Control Technology of Distributed Electric Propulsion Aircraf, College of Chemistry and Materials Engineering, Hunan University of Arts and Science, Changde 415000, China.
J Colloid Interface Sci. 2023 Jul 15;642:705-713. doi: 10.1016/j.jcis.2023.04.006. Epub 2023 Apr 5.
Mn-based NASICON-type NaMnV(PO) (NMVP) has been widely investigated as one of the most promising alternatives to NaV(PO) cathodes for sodium-ion batteries (SIBs) due to its higher energy density, higher abundance, and lower cost and toxicity compared to V. However, electrochemical performance for large-scale applications is limited by NMVP's inferior conductivity and structural degradation during cycling. Herein, a facile strategy to modify the surface/interphase properties of NMVP/C was reported using the thermally stable Al(PO) precursor with a wet process followed by heat treatment to enhance the interface stability of electrodes. The nanomodified layer has the benefits of an ionic conductor (slight NaPO) and robust composite (Al(PO)), which can facilitate the stability of Mn-based cathode materials and ionic conductivity. These merits endow 1 wt% Al(PO)-loaded NMVP/C cathodes with a high rate performance (102/61 mAh g at 0.2/50 C) and impressive cyclability (88.5%/89.7% at 5 C/10 C after 3000/4000 cycles) in Na-ion batteries at 2.5-3.8 V. Moreover, when the cutoff voltage is raised to 4 V, improved electrochemical properties (111.6/50.8 mAh g at 0.2/10 C and 71.4% after 1000 cycles at 5 C) are also realized. Such an enhancement indicates that facial surface modification engineering limits organic electrolyte erosion, inhibits transition metal dissolution and suppresses surface lattice degradation, which is confirmed by ex situ X-ray diffractometry and transmission electron microscopy. Therefore, the Al(PO) surface modification strategy combined with mechanism analysis can provide a possible reference for advanced electrochemical properties in energy storage devices.
基于锰的 NASICON 型 NaMnV(PO)（NMVP）由于其比钒更高的能量密度、更高的丰度、更低的成本和毒性，已被广泛研究作为钠离子电池（SIBs）中最有前途的替代物之一。然而，由于 NMVP 的导电性差和循环过程中的结构降解，其大规模应用的电化学性能受到限制。在此，我们报告了一种通过使用热稳定的 Al(PO)前体和随后的热处理通过湿化学工艺来修饰 NMVP/C 表面/界面性质的简便策略，以提高电极的界面稳定性。纳米修饰层具有离子导体（轻微的 NaPO）和坚固复合材料（Al(PO)）的优点，可促进基于锰的正极材料的稳定性和离子导电性。这些优点使 1wt%Al(PO)负载的 NMVP/C 正极在 2.5-3.8V 下具有高倍率性能（在 0.2/50C 时为 102/61mAh g）和出色的循环稳定性（在 5C/10C 下经过 3000/4000 次循环后分别为 88.5%/89.7%）。此外，当截止电压提高到 4V 时，还实现了改进的电化学性能（在 0.2/10C 时为 111.6/50.8mAh g，在 5C 下经过 1000 次循环后为 71.4%）。这种增强表明，表面改性工程限制了有机电解质的侵蚀，抑制了过渡金属的溶解，并抑制了表面晶格的降解，这通过原位 X 射线衍射和透射电子显微镜得到了证实。因此，结合机制分析的 Al(PO)表面改性策略可为储能器件的先进电化学性能提供可能的参考。
