Abstract

Significance This study aims to conduct a comprehensive review of the latest research advancements in micro- and nano-powder fillers for composite solid electrolytes （CSEs）， offering valuable insights for the development of novel filler materials with superior ionic conductivity， exceptional mechanical properties， and excellent chemical stability. CSEs exhibit remarkable attributes， including high ionic conductivity， easy processing， and a broad electrochemical window. Fillers play a crucial role in enhancing the physical and chemical properties of CSEs. This review encompasses recent research achievements in fillers， elucidating their mechanisms for improving the electrochemical performance of CSEs by reducing polymer chain crystallinity， facilitating lithium salt dissociation， and stabilizing anionic species. Furthermore， it outlines the strengths and limitations of fillers while emphasizing the design principles for different types of fillers. The prospects for research and application of CSE fillers are promising， with future directions focusing on material innovation， optimization of filler design， utilization of advanced characterization techniques， and expansion into new application areas. These efforts are expected to significantly advance solid-state lithium metal battery technology.

Progress The polymers commonly utilized in this process， such as polyethylene oxide （PEO）， polyethylene glycol diacrylate （PEGDA）， and polyvinylidene fluoride （PVDF）， typically demonstrate relatively high crystallinity at room temperature. The incorporation of fillers， including inert materials like Al₂O₃， BaTiO₃， as well as fast ion conductors such as LLZTO， effectively reduces polymer crystallinity and improves the mobility of polymer chains. Early research primarily concentrated on exploring Lewis acid-base interactions between fillers and polymers， proposing that rapid ion conduction channels could be established on filler surfaces. Subsequent studies have focused on constructing these swift ion conduction channels， which are closely linked to the orientation and morphology of fillers within the polymer matrix. Recent advancements have discovered complex interactions among polymers， fillers， and lithium salts within CSEs. These interactions manifest primarily in two aspects： （1） the interplay between fillers and lithium salts， which involves changes in chemical environment of lithium ions， chiefly reflected in variations of ionic conductivity and lithium ion transference numbers （t_Li⁺）； （2） the interplay between fillers and polymers， involving modifications in polymer's structural composition， reflected in changes of crystallinity （X_c）， glass transition temperature （T_g）， and spherulite formation. Despite this progress， interface stability remains the fundamental challenge for solid-state lithium batteries （SSLBs）. These challenges are influenced by interactions at both CSEs/cathode and CSEs/anode surfaces， including issues such as inadequate electrolyte/electrode contact， lithium dendrite growth， and high-voltage decomposition.

Conclusions and Prospects CSEs exhibit tremendous potential in advancing solid-state battery technology through the incorporation of fillers to enhance their performance. This review presents a comprehensive review of various types of fillers， including inert， active， and functional fillers， as well as their characteristics and impact mechanisms on CSE performance. It illuminates the synergistic effects of fillers in enhancing electrochemical performance by reducing polymer chain crystallinity， facilitating lithium salt dissociation， and stabilizing anions. Notably， the interface interactions between fillers and the polymer matrix are pivotal for establishing rapid Li⁺ transport pathways. By optimizing filler dispersion and improving interface compatibility， the migration rate of lithium ions can be significantly enhanced， thereby improving the conductive properties of electrolytes. Despite significant progress in optimizing filler properties through various strategies， challenges such as the impact of fillers on ion transport dynamics， non-uniform lithium deposition， and dendrite formation still exist. Future research should focus on the following directions： 1） Material innovation. Leveraging artificial intelligence models to identify and design new fillers； 2） Filler optimization. Investigating microstructural features of fillers and their effects on performance； 3） Advanced characterization techniques. Utilizing cutting-edge characterization methods to explore the dynamic changes of fillers throughout the process of charging and discharging； 4） High-pressure compatibility. Developing composite fillers integrated with small molecule plasticizers to improve interfacial stability.

Keywords： powder filler； particle scale； composite solid electrolyte； solid-state lithium metal battery

Get Citation: CHENG Hongwei， DUAN Tong， LI Jiamin， et al. Research progress of micro- and nano-powder fillers in composite solid electrolytes［J］. China Powder Science and Technology， 2025， 31（4）： 1-13.

Received: 2024-10-18.Revised: 2024-11-20,Online: 2025-03-31.

Funding Project: 国家自然科学基金项目，编号 ：52404423，51874196；上海市自然科学基金，编号：23ZR1421600。

First Author: 程红伟（1980—），男，教授，博士，博士生导师，上海市东方学者，研究方向为资源综合利用与电化学储能。E-mail：hwcheng@shu.edu.cn。

DOI：10.13732/j.issn.1008-5548.2025.04.002

CLC No: TB4；TM912；O646.1     Type Code: A

Serial No:1008-5548（2025）04-0001-13