硅酸盐学报

掺杂Mg²⁺提高NASICON型固体电解质离子电导率的机理

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陈春颖 ¹^,² , 任进军 ¹^,²

硅酸盐学报 | 研究论文 2026,54(1): 133-142

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硅酸盐学报 |研究论文 2026 , 54 (1) : 133 -142

掺杂Mg²⁺提高NASICON型固体电解质离子电导率的机理

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陈春颖¹^,², 任进军¹^,²

作者信息

^1．中国科学院上海光学精密机械研究所，特种玻璃与光纤研究中心，先进激光与光电功能材料部，上海 201800

^2．中国科学院大学，材料科学与光电工程中心，北京 100049

通讯作者:

任进军（1979—），男，博士，研究员。

作者简介:

陈春颖（1996—），女，博士研究生。

Mechanism of Mg²⁺ Doping to Enhance the Ionic Conductivity of NASICON-Type Solid-State Electrolytes

Chunying CHEN¹^,², Jinjun REN¹^,²

Affiliations

^1.Advanced Laser and Optoelectronic Functional Materials Department, Special Glasses and Fibers Research Center, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China

^2.Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China

Corresponding Author:

REN Jinjun (1979-), male, Ph.D., Professor. E-mail: renjinjunsiom@163.com

CHEN Chunying (1996-), female, Doctoral candidate. E-mail: chenchunying@siom.ac.cn

出版时间: 2026-01-20 doi: 10.14062/j.issn.0454-5648.20250160

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摘要

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NASICON 型固体电解质因其卓越的离子导电性能，在能源存储领域展现出广阔的应用前景。为了提升以Na₃Zr₂Si₂PO₁₂为基础组分的NASICON型固体电解质的离子导电性能，一种常见的策略是通过掺杂低价态阳离子来取代Zr⁴⁺，从而增加固体电解质中的Na⁺离子浓度，最终实现离子电导率的提升。本工作制备了一系列掺杂Mg²⁺的Na₃₊₂_xMg_xZr_2-_xSi₂PO₁2 （NMZSPx，0 ≤ x ≤ 0.20）固体电解质陶瓷样品，旨在深入探究Mg²⁺掺杂对离子电导率提升的作用机理。实验结果表明，随着Mg²⁺掺杂量的增加，NMZSPx的离子电导率先升后降，x = 0.12时达到最大值，其在25 ℃的离子电导率为1.54 × 10^-3 S·cm^-1，相较于未掺杂样品提升了3.13倍。为了揭示Mg²⁺掺杂对固体电解质结构的影响，进行了X射线衍射、固态核磁共振以及扫描电子显微镜的元素分布检测实验。结果显示，大部分Mg²⁺并没有如预想般取代Zr⁴⁺，而是在晶界处形成了含Mg的磷酸盐杂相，只有极少量Mg²⁺进入NASICON主相中。尽管如此，含Mg磷酸盐杂相的生成却间接地提高了NASICON中Na⁺的含量，但这并非离子导电性能提升的主要原因。SEM结果显示，适量掺杂Mg²⁺可以显著降低陶瓷样品的孔隙率、增强晶界连接性并降低晶界阻抗；而过量掺杂Mg²⁺会导致杂相及孔隙增多，从而阻碍载流子传输。Mg²⁺掺杂对NMZSPx陶瓷样品孔隙率的改变才是改变离子电导率的主要原因。

关键词

NASICON / 固体电解质 / 离子电导率 / 镁离子掺杂 / 固态核磁共振

Abstract

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Introduction

Sodium-ion batteries (SIBs) have garnered significant attention as a promising alternative to lithium-ion batteries (LIBs) due to the abundance and cost-effectiveness of sodium resources. However, the development of high-performance solid-state electrolytes remains a major challenge in the advancement of SIBs. NASICON-type solid electrolytes, specifically Na₃Zr₂Si₂PO₁2 (NZSP), are known for their excellent ionic conductivity and structural stability, making them ideal candidates for use in SIBs. To further enhance their ionic conductivity, one common strategy is to dope low-valence cations into the structure, potentially replacing Zr⁴⁺ ions and increasing the concentration of Na⁺ ions. Despite the widespread use of Mg²⁺ doping in NASICON materials to enhance ionic conductivity, the underlying mechanism remains underexplored. Therefore, the aim of this study is to investigate the effect of Mg²⁺ doping on the microstructure and ionic conductivity of Na₃₊₂_xMg_xZr_2-_xSi₂PO₁₂ (NMZSPx) solid-state electrolyte ceramics and elucidate the underlying mechanism of ionic conductivity enhancement.

Methods

In this study, a series of Mg²⁺ doping Na₃₊₂_xMg_xZr_2-_xSi₂PO₁₂ (NMZSPx, 0 ≤ x ≤ 0.20) ceramics were synthesized via a traditional sintering method. The samples were characterized using several techniques, providing insights into the electrical properties and conductivity mechanisms. Electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the ionic conductivities of the samples across a range of temperatures. X-ray diffraction (XRD) analysis was employed to investigate the phase composition and crystalline structure of the samples. Solid-state nuclear magnetic resonance (SSNMR) spectroscopy, including ³¹P, ²⁹Si, and ²³Na Magic Angle Spinning (MAS) NMR, was used to analyze the local atomic environments and determine the distribution of different elements in the ceramics. Scanning electron microscopy (SEM) was used to examine the microstructure of the ceramics, with individual elemental maps to assess the distribution of Na, Mg, Zr, Si, P, and O elements.

Results and discussion

The results of this study reveal that Mg doping significantly affects both the microstructure and the ionic conductivity of Na₃₊₂_xMg_xZr_2-_xSi₂PO₁₂ ceramics. As the Mg²⁺ doping concentration increases, the ionic conductivity initially increases, reaching a peak value at x = 0.12, with a conductivity of 1.54 × 10^-3 S·cm^-1 at 25 ℃, which is 3.13 times higher than that of the undoped sample. However, further doping beyond x = 0.12 leads to a decrease in conductivity, indicating an optimal doping concentration for ionic conductivity enhancement. XRD analysis indicates that the samples with doping amount x > 0.12 exhibit a characteristic diffraction peak of rhombohedral crystal at 30.2°. This indicates that as the amount of Mg²⁺ doping increases, the NASICON main phase of NMZSPx samples gradually transitions from monoclinic phase to rhombohedral phase. Mg²⁺ ions do not replace Zr⁴⁺ ions in the NASICON main phase as previously assumed. Instead, a large portion of Mg²⁺ ions preferentially forms sodium magnesium phosphate heterogeneous phases at the grain boundaries. This observation is consistent with the results from SSNMR, where the chemical shifts of those signal peaks in the ³¹P, ²⁹Si, and ²³Na MAS NMR spectra show significant changes in the local environments of these elements, reflecting the influence of Mg²⁺ doping on the phase composition and atomic distribution. The formation of these magnesium phosphate secondary phases indirectly increases the concentration of Na⁺ by altering the Si/P ratio in the NASICON structure. However, the increase in Na⁺ concentration is not the primary reason for the enhanced ionic conductivity. The key factor contributing to the increased ionic conductivity is the improvement in the microstructure of the NMZSPx ceramics. SEM images show that appropriate Mg²⁺ doping significantly reduces the porosity of the ceramic samples and enhances the connectivity at the grain boundaries, facilitating easier Na⁺ transport. Specifically, x = 0.12 sample exhibits the densest microstructure, with good contact between grains and no noticeable defects, resulting in the highest ionic conductivity. However, excessive Mg²+doping (x > 0.12) leads to the formation of more impurity phases and increased porosity, which hinders ion transport across the grain boundaries, resulting in a decrease in ionic conductivity. This suggests that while Mg²⁺ doping can improve the ceramics' microstructure and reduce grain boundary resistance up to a certain point, excessive doping leads to the formation of impurity phases that impede ionic conduction.

Conclusions

This study demonstrates that Mg²⁺ doping in Na₃₊₂_xMg_xZr_2-_xSi₂PO₁₂ ceramics enhances ionic conductivity by improving the microstructure, particularly by reducing porosity and enhancing grain boundary connectivity. The optimal doping concentration of Mg²⁺ ions is found to be x = 0.12, which exhibits the highest ionic conductivity. However, excessive Mg²⁺ doping leads to the formation of sodium magnesium phosphate heterogeneous phases and increased porosity, which hinders ion transport and reduces the overall conductivity. The results also suggest that Mg²⁺ ions primarily influence the NMZSPx ceramics' conductivity by modifying the microstructure and inducing the formation of impurity phases at the grain boundaries, rather than directly substituting for Zr⁴⁺ ions in the NASICON structure. These findings provide new insights into the role of Mg²⁺ doping in enhancing the ionic conductivity of NASICON-type solid-state electrolytes and highlight the importance of optimizing doping concentrations to balance the formation of impurity phases and the improvement of microstructural properties.

Key words

NASICON / solid-state electrolyte / ionic conductivity / magnesium ion doping / solid-state nuclear magnetic resonance

引用本文

陈春颖, 任进军. 掺杂Mg²⁺提高NASICON型固体电解质离子电导率的机理. 硅酸盐学报, 2026 , 54 (1) : 133 -142 . DOI: 10.14062/j.issn.0454-5648.20250160

Chunying CHEN, Jinjun REN. Mechanism of Mg²⁺ Doping to Enhance the Ionic Conductivity of NASICON-Type Solid-State Electrolytes[J]. Journal of the Chinese Ceramic Society, 2026 , 54 (1) : 133 -142 . DOI: 10.14062/j.issn.0454-5648.20250160

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中国科学院战略重点研究计划(XDB0650000)

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2026年第54卷第1期

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文章信息

doi: 10.14062/j.issn.0454-5648.20250160

接收时间：2025-03-11
首发时间：2026-10-27
出版时间：2026-01-20

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收稿日期：2025-03-11
修回日期：2025-04-11

基金

中国科学院战略重点研究计划(XDB0650000)

作者信息

^1．中国科学院上海光学精密机械研究所，特种玻璃与光纤研究中心，先进激光与光电功能材料部，上海 201800

^2．中国科学院大学，材料科学与光电工程中心，北京 100049

通讯作者:

任进军（1979—），男，博士，研究员。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20250160

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2种不同金属材料的力学参数

科 Family	属数 Number of genus	种数 Number of species	占总种数比例 Percentage of total species (%)	属 Genus	种数 Number of species	占总种数比例 Percentage of total species (%)
鹅膏菌科Amanitaceae	2	11	5.26	鹅膏菌属 Amanita	10	4.78
小菇科 Mycenaceae	2	12	5.74	丝盖伞属 Inocybe	5	2.39
多孔菌科 Polyporaceae	8	14	6.70	蜡蘑属 Laccaria	5	2.39
红菇科 Russulaceae	3	23	11.00	小皮伞属 Marasmius	6	2.87
				小菇属 Mycena	11	5.26
				光柄菇属 Pluteus	5	2.39
				红菇属 Russula	17	8.13
				栓菌属 Trametes	5	2.39

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