Solid-state lithium batteries (SSLBs) represent a transformative advancement in energy storage technology, playing a pivotal role in achieving global “dual carbon” goals. These batteries also offer a significant breakthrough in overcoming the energy density and safety limitations inherent in conventional lithium-ion batteries. Unlike conventional liquid electrolytes, solid electrolytes mitigate some critical issues such as electrolyte leakage and flammability, thus substantially enhancing the safety of SSLBs. Among various solid-state electrolyte candidates, composite solid electrolytes (CSEs) have attracted much attention due to their potential for commercial viability. Nevertheless, three major challenges remain to be addressed for the practical application of CSEs, i.e., (ⅰ) limitations in ionic conduction dynamics. Most CSEs exhibit room-temperature ionic conductivities ranging from 10⁻⁶ to 10⁻³ S·cm⁻¹, which are one to three orders of magnitude lower than those of liquid electrolytes (i.e., ~10⁻² S·cm⁻¹), severely restricting the rate and low-temperature performance of SSLBs; (ⅱ) poor mechanical properties. Despite some CSEs possessing high Young’s moduli, localized current concentration at micro-defects can lead to lithium dendrite formation and propagation, posing a significant risk of internal short circuits; and (ⅲ) solid–solid interfacial compatibility issues. Physical defects and chemical side reactions at the electrode–CSE interface can lead to continuous increases in interfacial impedance, thereby compromising the cycle life and stability of SSLBs.

Layered silicate minerals, including montmorillonite, attapulgite, and halloysite, are naturally occurring silicates with unique nanoscale structures. These minerals are abundant, cost-effective, and readily available in regions such as China. Layered silicates present a substantial potential for enhancing the ionic conductivity, mechanical properties, and interfacial stability of CSEs due to their high specific surface area, tunable chemical properties, and distinct nano-structural characteristics.

This review systematically explores the structural characteristics of layered silicate minerals and their functionalization strategies to enhance ion transport, interfacial stability, and mechanical properties within CSEs. The crystal structures, micro-morphologies, and surface/interface properties of layered silicates affect ion migration mechanisms, reinforcement of mechanical properties, and regulation of interfacial stability in composite electrolytes. In addition, the review also represents recent advancements on utilizing layered silicate minerals and their functional modifications for improving CSEs.

Layered silicate minerals offer several unique advantages in CSEs, i.e., (ⅰ) Their unique structural properties provide excellent pathways for ion conduction, with some even exhibiting inherent ion-conductive behavior; (ⅱ) As inorganic fillers, they promote the dissociation of lithium salts through Lewis acid-base interactions, while suppressing polymer crystallization, significantly boosting the ionic conductivity of the composite electrolyte; and (ⅲ) The high modulus and thermal stability of layered silicate minerals improve the mechanical properties and thermal stability of CSEs.

Layered silicate mineral-based composite solid electrolytes have an immense potential for advancing solid-state battery technologies. However, several scientific and technical challenges remain. First, the complexity of material composition and structural stability are key factors that restrict the performance. Variations in the batch-to-batch properties of layered silicate minerals result in compositional inhomogeneity. Furthermore, their high surface energy leads to agglomeration, disrupting ion conduction channels and stress distribution, which negatively impacts ionic conductivity and interfacial compatibility. The presence of impurities in the minerals, which are difficult to eliminate, may also induce side reactions that degrade the electrolyte-electrode interface, hindering performance improvement. Second, ion transport in these materials is constrained by small interlayer spacings and suboptimal interface compatibility, leading to a low ionic conductivity at room and low temperatures. This limits the realization of high conductivity. Moreover, the trade-off between mechanical properties and ionic conductivity complicates the simultaneous enhancement. The electrolyte stability under extreme conditions (such as low temperatures and high-voltage environments) is also a challenge. Polymer crystallization and interlayer contraction at low temperatures significantly reduce conductivity, while high-voltage conditions lead to electrolyte decomposition and electrode compatibility issues.

To overcome these challenges, a future research should focus on the following aspects, i.e., ⅰ) Multistage purification and interface modification to address heterogeneity and agglomeration, improving ionic conductivity and stability through interdisciplinary collaboration; ⅱ) Control of interlayer spacing and surface modification, using ionic liquids and silane coupling agents to expand interlayer spacing and enhance interface properties, thereby improving ion transport efficiency; ⅲ) Design of three-dimensional network structures, integrating layered silicate minerals with various morphologies to construct ordered 3D networks, enhancing both the mechanical and electrochemical properties of the composite material; ⅳ) Extreme-condition adaptability, developing stable electrolytes for low-temperature and high-voltage environments through functionalization and additive optimization; and ⅴ) Scalable, environmentally friendly fabrication techniques, such as water-based dispersion and UV curing, to reduce production costs and improve batch-to-batch consistency. Layered silicate mineral-based composite solid electrolytes will play a crucial role in the development of solid-state battery technologies and accelerate their commercialization via advancing research in these aspects.