Solid-state batteries have become a frontrunner in humankind’s pursuit of safe and stable energy storage systems with high energy and power density. Electrolyte materials, currently, seem to be the Achilles’ heel of solid-state batteries due to the slow kinetics and poor interfacial wetting. Combining the merits of solid inorganic electrolytes (SIEs) and solid polymer electrolytes (SPEs), inorganic/polymer hybrid electrolytes (IPHEs) integrate improved ionic conductivity, great interfacial compatibility, wide electrochemical stability window, and high mechanical toughness and flexibility in one material, having become a sought-after pathway to high-performance all-solid-state lithium batteries. Herein, we present a comprehensive overview of recent progress in IPHEs, including the awareness of ion migration fundamentals, advanced architectural design for better electrochemical performance, and a perspective on unconquered challenges and potential research directions. This review is expected to provide a guidance for designing IPHEs for next-generation lithium batteries, with special emphasis on developing high-voltage-tolerance polymer electrolytes to enable higher energy density and three-dimensional (3D) continuous ion transport highways to achieve faster charging and discharging.

Polymer-brush architectures have attracted great interests in solid-state electrolytes for battery applications due to the facilitated segmental dynamics and latent capacity to fabricate single ion conductors. The effect of side chain architectures on the ionic conductivity of the polymer-brush electrolytes (PBEs), however, still requires a systematic exploration. This work describes a detailed study on the structure−property relationship between the side chain architectures and the ion-conducting behaviors of PBEs. By means of thermodynamic, spectroscopic, and electrochemical characterizations, factors of both chain length and graft density are investigated to elucidate the mechanism. Our results show that as the chain length increases, the ionic conductivity exhibits first an increase in the short amorphous range and then a drop in the long crystalline range. Moreover, investigation on graft density demonstrates that the amorphous PBEs achieve the highest ionic conductivity at a fully grafted configuration, indicating the significance of branched side chain architecture. For crystalline PBEs, proper regulation of graft density can alleviate the crystallization of the side chains and therefore increase the ionic conductivity. These results would improve our understanding of ion-conducting behaviors in PBEs and provide insights for designing advanced solid polymer electrolytes.