Abstract

Significance The transport mechanisms of lithium ions in solid polymer electrolytes （SPEs） are critical for determining the performance of next-generation batteries. The mechanisms encompass multiple intricate processes， including ion coordination， intra- and inter-chainhopping， and segmental motions of polymer chains. These processes collectively influence essential parameters such as ionic conductivity and lithium-ion mobility， which are pivotal for the development of high-performance SPEs. However， a fundamental understanding of these mechanisms remains a key challenge，and the rational design of advanced SPEs is required. This paper comprehensively reviews the research progress in this field， covering theoretical models， experimental spectroscopic characterization， and computational simulations， highlighting future research directions and opportunities.

Progress Historically， the investigation of ion transport in SPEs has employed empirical and semi-empirical models to describe the temperature- and composition-dependent ionic conductivity. Among these， the Arrhenius model has been widely employed to characterize thermally activated ion transport， particularly in crystalline or glassy electrolytes. However， it often fails to capture the complex behavior of polymer systems， where segmental motion dominates. The Vogel-Tammann-Fulcher （VTF） model addresses this limitation by incorporating free volume and glass transition temperature， making it more appropriate for amorphous polymers. The William-Landel-Ferry （WLF） equation further refines this approach by providing a more nuanced description of temperature-dependent polymer dynamics. However， these models have inherent limitations and need experimental data to achieve a more precise prediction of ion transport behavior in SPEs.Recent advancements in spectroscopic techniques have revolutionized our understanding of the dynamic processes underlying lithium ion transport in SPEs. Infrared （IR） spectroscopy， for instance， has been instrumental in probing the coordination environment of lithium ions and their interactions with polymer chains. Terahertz （THz） spectroscopy offers a distinctive perspective on the low-frequency dynamics of ions and polymer segments， revealing details about ion hopping and collective motion. These techniques， often combined with time-resolved measurements， have enabled the direct observation of real-time ion coordination states and transport processes. Such experimental breakthroughs are invaluable for validating theoretical models and guiding the design of novel SPE materials.Molecular dynamics （MD） simulations have emerged as an essential tool for studying ion transport in SPEs at the atomic and molecular levels. Classical MD simulations， utilizing empirical force fields， are widely used due to their balance between computational efficiency and accuracy. These simulations have significantly advanced our understanding of ion coordination， polymer segmental motion， and ion hopping. However， the simulation accuracy is often constrained by the quality of the force fields， particularly for complex polymer systems. Recent methodological advancements have promoted the development of coarse-grained MD techniques， where computational costs are substantially reduced by simplifying the representation of polymer chains while preserving critical physical features. Additionally， machine learning-based MD simulations have emerged as an advantageous alternative， potentially achieving quantum-level accuracy at a significantly lower computational cost. These advanced simulation methods are particularly promising for studying complex interfacial phenomena in composite electrolytes and electrode-electrolyte systems.Despite significant progress， several challenges persist. A prominent challenge lies in the development of accurate and transferable force fields for MD simulations， especially for multi-component systems and interfaces. Another challenge is the integration of experimental and computational approaches to provide a more holistic understanding of ion transport mechanisms. For example， combining spectroscopic data with MD simulations can bridge the gap between macroscopic properties and microscopic processes. Additionally， the development of new electrolyte materials， such as hybrid organic-inorganic electrolytes and gel-based systems， presents new opportunities and challenges for both experimental and computational studies. Future research should also focus on translating these insights into practical battery systems， with particular attention to electrode compatibility， cycling stability， and safety.

Conclusions and Prospects Understanding the transport mechanisms of lithium ions in SPEs is a complex scientific challenge that demands integrated theoretical， experimental， and computational studies. Although significant progress has been made， many challenges persist， particularly in relation to complex materials and interfaces. Advancements in spectroscopic techniques， MD simulations， and machine learning methods are promising in addressing these issues. A deeper understanding of ion transport in SPEs could pave the way for the development of next-generation batteries with improved performance， safety， and sustainability. This review highlights the importance of interdisciplinary collaboration and innovative methodologies in advancing this critical research field.

Keywords： solid polymer electrolyte； transport mechanism； empirical model； molecular dynamics simulation； spectral charact-erization

Get Citation: LI Wenliang， LI Chunguang， SUN Hao. Lithium-ion transport mechanisms in solid polymer electrolytes［J］. China Powder Science and Technology， 2025， 31（4）： 1-15.

Received:2025-03-27.Revised:2025-05-29, Online: 2025-06-10

Funding Project:国家自然科学基金项目， 编号： 22279014； 吉林省发展与改革委员会基金项目， 编号： 2024C018-3 。

First Author:李文亮（1983—），男，副教授，博士，博士生导师，吉林省优秀青年基金获得者，研究方向为电池材料设计与模拟。E-mail：liwl926@nenu.edu.cn。

Corresponding Author:李春光（1984—），男，工程师，硕士。研究方向为混合储能系统。E-mail：lichunguang@nepdi.net。

DOI：10.13732/j.issn.1008-5548.2025.04.004

CLC No:O631；TB4   Type Code: A

Serial No:1008-5548（2025）04-0001-15