硅酸盐学报

金属锂负极有机-无机复合人工界面层的理论机制

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高文霞 ¹^,² , 方诗豪 ¹ , 毛鑫 ¹ , 刘畅 ³^,⁴ , 喻学锋 ¹ , 彭超 ¹

硅酸盐学报 | 电化学储能材料计算与设计专题—研究论文 2025,53(7): 1902-1911

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硅酸盐学报 |电化学储能材料计算与设计专题—研究论文 2025 , 53 (7) : 1902 -1911

金属锂负极有机-无机复合人工界面层的理论机制

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高文霞¹^,², 方诗豪¹, 毛鑫¹, 刘畅³^,⁴, 喻学锋¹, 彭超¹

作者信息

^1．中国科学院深圳先进技术研究院，广东深圳 518055

^2．中国科学院大学，北京 101408

^3．湖北兴发化工集团股份有限公司，湖北宜昌 443711

^4．湖北三峡实验室，湖北宜昌 443007

通讯作者:

彭超（1990—），男，博士，副研究员；

刘畅（1978—），女，硕士，工程师；

毛鑫（1993—），男，博士。

作者简介:

高文霞（1998—），女，硕士研究生。

Mechanism of Organic-Inorganic Composite Artificial Interface Layer for Lithium Metal Anode

Wenxia GAO¹^,², Shihao FANG¹, Xin MAO¹, Chang LIU³^,⁴, Xuefeng YU¹, Chao PENG¹

Affiliations

^1.Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, Guangdong, China

^2.University of Chinese Academy of Sciences, Beijing 101408, China

^3.Hubei Xingfa Chemicals Group Co. Ltd., Yichang 443711, Hubei, China

^4.Hubei Three Gorges Laboratory, Yichang 443007, Hubei, China

Corresponding Author:

PENG Chao (1990-), male, Ph.D., Associate Professor. E-mail: chao.peng@siat.ac.cn;

LIU Chang (1978-), female, M.S., Engineer. 466578168@qq.com;

MAO Xin (1993-), male, Ph.D. xin.mao2@siat.ac.cn

GAO Wenxia (1998-), female, Master candidate. E-mail: wx.gao@siat.ac.cn

出版时间: 2025-07-20 doi: 10.14062/j.issn.0454-5648.20250020

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摘要

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基于分子自组装方法在金属锂负极界面构筑功能性人工界面层，可以定向调控固体电解质界面（SEI）性能，进而优化金属锂负极的稳定性和安全性。本工作结合密度泛函理论和从头算分子动力学模拟方法，系统研究了头部不同含氟量的自组装分子与金属锂表面相互作用和结构演化，并重点探讨了分子头部氟端基结构对界面有机-无机复合人工界面层性能的调控作用。研究发现，随着自组装分子覆盖度的增加，分子头部端基F与金属锂发生氟化反应并形成LiF，降低了体系形成能，使得高覆盖度下界面有机-无机复合人工界面层的稳定性和致密性得到提升。态密度等电子结构分析表明，氟化物的引入改善了金属锂的局域电子结构，促进了锂离子在界面上的嵌入和扩散，并限制了电子向有机分子层的传输。从头算分子动力学模拟揭示，头部含三氟的分子相比于含一氟的分子，动态演化形成的人工界面层更厚、更均匀、氟配位数更高、锂扩散系数更大，表现出更优的稳定性。静电势分析表明，三氟分子形成的人工界面层具有更低的电势，热力学上更有利于锂离子输运。因此，通过自组装分子头部含氟量的调控能有效促进金属锂负极界面SEI层的稳定性和优化锂离子输运性能，这为设计锂负极界面高性能人工界面层提供了很好的理论依据。

关键词

金属锂负极 / 分子自组装 / 人工界面层 / 氟化锂 / 密度泛函理论

Abstract

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Introduction

Lithium-metal batteries (LMBs), as next-generation high-energy-density battery technologies, have attracted considerable attention due to their theoretical energy density (i.e., approximately 3860 mA·h/g), which far exceeds that of conventional lithium-ion batteries (LIBs). This makes LMBs highly promising for applications in electric vehicles, portable electronic devices, and other fields. Compared to conventional LIBs with a theoretical capacity of 372 mA·h/g for graphite anodes, LMBs can offer a longer battery life or a higher energy output, thus addressing the energy density bottleneck faced by the existing energy storage technologies. As a result, LMBs are widely regarded as an important direction for the future development of battery technologies. However, despite the significant advantages of LMBs in terms of energy density, the use of lithium metal anodes still has some challenges. Some issues like dendrite growth and instability of the solid electrolyte interphase (SEI) severely restrict their practical application. It is thus critical to suppress lithium dendrite growth and improve the stability of SEI.

Although the existing studies propose the use of artificial interphase layers to optimize the stability and safety of lithium metal anodes, there is a lack of systematic theoretical guidance, particularly in terms of how to regulate the composition and structure of the interphase layer. This study was to construct functional artificial interphase layers on the lithium metal anode surface by molecular self-assembly techniques. This study also regulated the SEI performance via utilizing self-assembled molecules with varying fluorine contents, thus enhancing the stability and safety of lithium metal anodes and providing a theoretical basis for future interface layer design in lithium metal batteries.

Methods

This study used the density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations to systematically investigate the interaction and structural evolution of self-assembled molecules with different fluorine contents on lithium metal surfaces. The focus was to clarify how fluorine-terminated molecular structures could affect the performance of the organic-inorganic composite artificial interphase layer.

The calculations were performed by a Vienna Ab-initio Simulation Package (VASP) based on the density functional theory. The VASP employs the projector-augmented wave (PAW) method and the Perdew-Burke-Ernzerhof (PBE) functional within the generalized gradient approximation (GGA). All the calculations used Γ-point centered Brillouin zone sampling to ensure accuracy. The PAW method was used for electron-ion interactions with an energy cutoff of 450 eV. Convergence criteria for energy and force were set at 1×10^-4 eV and 0.05 eV/Å, respectively. The van der Waals interactions were determined by the DFT-D3 method. The density of states (DOS), charge differential density, and Bader charge distribution were calculated to characterize an interfacial electronic behavior. Organic-inorganic composite interphase layers were constructed by the molecular models with varying fluorine termini (i.e., F₁∶C₉H₁₉F, F₃∶C₉H₁₇F₃), and the molecular adsorption behavior was analyzed by coverage gradient models to evaluate the adsorption stability through formation energy calculations. The AIMD simulations were conducted to explore the dynamic behavior of the interphase layer. The 20 ps simulations were performed at 300 K (Nosé-Hoover thermostat) with one time step of 1 fs. Lithium ion diffusion coefficients were calculated via mean square displacement (MSD), and the structural characteristics of the interphase layer were analyzed via radial distribution functions (RDF) and coordination numbers.

Results and discussion

This study systematically reveals the regulatory mechanisms of fluorine-terminated self-assembled molecules on lithium metal anode interphase layers based on theoretical calculations and dynamic simulations. On the Li(100) lithium metal surface, higher fluorine content molecules (F₃∶C₉H₁₇F₃) exhibit stronger interfacial binding capabilities. The fluorine groups at the molecule heads react with lithium to form LiF as molecular coverage increases, significantly reducing the system formation energy and thereby enhancing the stability and density of the interphase layer. At a high coverage, the fluorine atoms at the heads of F₃ molecules reactwith lithium to form an amorphous LiF layer with a thickness of 6.2 Å (compared to 3.8 Å for the F₁ system), substantially inhibiting interfacial structural relaxation. The DOS analysis indicates that in the LiF layer formed by the F₃ system, Li-F orbitals overlap significantly at -7.5 eV, indicating a strong ionic bonding. The interfacial electrostatic potential is lower for the F₃ system (-4.87 eV), and the thicker LiF layer formed by F₃ molecules results in a a wider negative potential region, and more conducive to lithium ion intercalation/extraction. Lithium ion diffusion dynamics analysis shows that the interphase layer formed by trifluorinated molecules is more stable based on the AIMD simulations with a thickness of 6.2 Å and a lithium ion diffusion coefficient of 4.76×10^-6 cm²/s, indicating a superior lithium ion transport performance. In contrast, the interphase layer formed by monofluorinated molecules has a lithium ion diffusion coefficient of 1.37×10^-5 cm²/s, showing a relatively inferior lithium ion transport performance.

Conclusions

This study used the DFT and AIMD simulations to systematically explore the interaction processes of self-assembled molecules with varying fluorine contents on lithium metal surfaces, and investigate the regulatory effects of fluorine-terminated groups on the performance of the organic-inorganic composite artificial interphase layer. The introduction of fluorine-terminated groups optimized the electronic structure of lithium metal, promoted lithium ion diffusion, and effectively inhibited electron transmission to the organic molecular layer, thereby enhancing an interphase layer stability. Increasing fluorine content enhanced the ionic nature of Li-F bonds, significantly reducing lithium vacancy formation energy and bonding strength, and improving lithium ion migration capability in the interphase layer. The interphase layers formed by trifluorinated self-assembled molecules had thicker structures, higher lithium ion diffusion coefficients, and exhibited a superior stability. This research elucidated the regulatory mechanisms of fluorine-terminated self-assembled molecules on lithium metal anode interphase layers in the atomic scale, providing a theoretical foundation for the design of high-performance lithium anode interphase layers based on molecular engineering, and extended the application prospects of self-assembly technology in the field of energy storage.

Key words

lithium metal anode / molecular self-assembly / artificial interface layer / lithium fluoride / density functional theory

引用本文

高文霞, 方诗豪, 毛鑫, 刘畅, 喻学锋, 彭超. 金属锂负极有机-无机复合人工界面层的理论机制. 硅酸盐学报, 2025 , 53 (7) : 1902 -1911 . DOI: 10.14062/j.issn.0454-5648.20250020

Wenxia GAO, Shihao FANG, Xin MAO, Chang LIU, Xuefeng YU, Chao PENG. Mechanism of Organic-Inorganic Composite Artificial Interface Layer for Lithium Metal Anode[J]. Journal of the Chinese Ceramic Society, 2025 , 53 (7) : 1902 -1911 . DOI: 10.14062/j.issn.0454-5648.20250020

基金

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国家自然科学基金(52203303)
中国科学院未来伙伴关系网络专项(321GJHZ2023189FN)
深圳市国际合作研究项目(GJHZ20220913142812025)

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2025年第53卷第7期

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文章信息

doi: 10.14062/j.issn.0454-5648.20250020

接收时间：2025-01-10
首发时间：2026-10-21
出版时间：2025-07-20

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收稿日期：2025-01-10
修回日期：2025-02-19

基金

国家自然科学基金(52203303)

中国科学院未来伙伴关系网络专项(321GJHZ2023189FN)

深圳市国际合作研究项目(GJHZ20220913142812025)

作者信息

^1．中国科学院深圳先进技术研究院，广东深圳 518055

^2．中国科学院大学，北京 101408

^3．湖北兴发化工集团股份有限公司，湖北宜昌 443711

^4．湖北三峡实验室，湖北宜昌 443007

通讯作者:

彭超（1990—），男，博士，副研究员；

刘畅（1978—），女，硕士，工程师；

毛鑫（1993—），男，博士。

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https://castjournals.cast.org.cn/joweb/gsyxb/CN/10.14062/j.issn.0454-5648.20250020

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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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