Room-temperature, high-voltage solid-state lithium battery with composite solid polymer electrolyte with in-situ thermal safety study

The low room-temperature ionic conductivity, narrow voltage window, and poor thermal stability of solid polymer electrolyte hinder the application of high energy density, safer solid-state lithium batteries (SLBs). Hence, we developed a novel composite solid polymer electrolyte (CSPE) with high room-temperature ionic conductivity (2.4 x 10(-4) S cm(-1)), wide voltage window (similar to 4.8 V), and excellent thermal stability (similar to 330 degrees C) by combining Li64La3Zr1.4Ta0.6O12 ceramic filler with poly(vinylidene fluoride) (PVDF) polymer and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt. Free-standing, scalable, and mechanically robust CSPE separately coupled with LiFePO4 and high-voltage LiNi1/3Co1/3Mn1/3O2 cathodes vs lithium anode demonstrated stable cycling. More importantly, we in-situ measured the thermal stable window (177 degrees C) with a small heat release (189 J g(-1)) during the thermal runaway of the entire CSPE coin cell. In contrast, the liquid electrolyte cell delivered a depressing thermal stable window (157 degrees C) and release a significant amount of heat (812 J g(-1)). The superior thermal safety of CSPE cell can be ascribed to the solid-state property and outstanding thermal stability of the CSPE. Most notably, this work not only proposes a promising CSPE but also highlights a reference for in-situ quantitative study on the thermal safety of entire SLBs.