Enhancing the Thermal Stability of NASICON Solid Electrolyte Pellets against Metallic Lithium by Defect Modification

Rusong Chen; Chunxia Yao; Qi Yang; Hongyi Pan; Xiqian Yu; Kai Zhang; Hong Li

doi:10.1021/acsami.1c01246

Enhancing the Thermal Stability of NASICON Solid Electrolyte Pellets against Metallic Lithium by Defect Modification

ACS Appl Mater Interfaces. 2021 Apr 28;13(16):18743-18749. doi: 10.1021/acsami.1c01246. Epub 2021 Apr 19.

Authors

Rusong Chen^{1

2}, Chunxia Yao³, Qi Yang^{1

4}, Hongyi Pan^{1

2}, Xiqian Yu^{1

2}, Kai Zhang³, Hong Li^{1

2}

Affiliations

¹ Beijing Advanced Innovation Center for Materials Genome Engineering, Key Laboratory for Renewable Energy, Beijing Key Laboratory for New Energy Materials and Devices, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
³ Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing 100049 China.
⁴ Beijing WeLion New Energy Technology Co., LTD, Beijing 102402, China.

PMID: 33871956
DOI: 10.1021/acsami.1c01246

Abstract

All-solid-state batteries (ASSBs) are expected to address the battery safety issues fundamentally by replacing the flammable electrolyte with solid electrolytes (SEs). However, recent studies report that the thermal runaway happened for NASICON-type SEs when they contact with Li metal at high temperature and indicate that the ASSBs may not be totally safe. Here, the thermal stability of a NASICON-type Li_1.4Al_0.4Ti_1.6(PO₄)₃ (LATP) SE pellet against metallic lithium is quantified in a quasi-practical situation. Accelerated thermal runaway of the LATP pellet compared to LATP powder is observed when they contact with lithium. Combining electrochemical impedance spectroscopy and X-ray computed tomography analysis, lithium penetration into the pellet at high temperature has been observed. The penetrated lithium without surface impurities and the high reactivity of LATP at defect sites (atomic structural defects, cracks, voids, etc.) lead to higher interfacial reactivity and earlier thermal runaway. By adding LiPO₂F₂ to modify those defect sites of the LATP pellet and impede the lithium/SE interfacial reactions, the thermal runaway can be remarkably delayed. This work elucidates the thermal runaway behaviors of Li/LATP pellets in a quasi-practical environment, provides new information about safety issues of ASSBs, and inspires future investigations into this urgent-needed area.

Keywords: Li-metal anode; battery safety; solid electrolyte; thermal runaway; thermal stability.