Self-Heating Mechanism of All-Solid-State Battery with Sulfide Electrolyte

Abstract

All-solid-state batteries (ASSBs) are expected to have less safety concern than Lithium-ion batteries with organic liquid electrolyte (LIBs) because flammable liquid electrolytes are not used in ASSBs. The thermal behaviors in LIBs have widely discussed in many literatures1. However, thermal behaviors of ASSBs have not investigated much.In this study, to clarify the self-heating phenomenon of our prototype ASSB with Argyrodite-type solid electrolyte we have performed calorimetric studies and gas analyses. In the calorimetric measurement, an accelerated rate calorimetry (ARC) was used to compare the starting temperature of self-heating in ASSB to that in LIB. It was found that the self-heating of ASSB takes place at 200-300ºC which was significantly higher than that in LIB.To identify the endothermic and exothermic peaks in the calorimetric profile and to estimate the amount of heat generation in ASSB, a Calvet-type calorimeter (C600) and a differential scanning calorimeter (DSC) were used with a heating rate of 1 ℃/min under Ar atmosphere for a full cell and electrode layers of the ASSB, respectively. The exothermic peaks at 200- 300℃ for charged ASSB (at ca. 4.1 V) mostly corresponded to those for the cathode layer which was extracted from the charged ASSB. The crystal structure change of the cathode layer charged at ca. 4.1 V associated with temperature change was analyzed by X-ray diffraction (XRD) to understand the reaction mechanism. The XRD peaks for the active material and the solid electrolyte in the cathode layer were disappeared at 200-300ºC. It was suggested that the heat generation at 200- 300ºC were mainly caused by the reaction between the cathode active material and the solid electrolyte.We also analyzed the evolved gas during the heating of ASSB using a temperature-programmed desorption-mass spectrometry (TPD-MS). The detailed mechanism will be discussed on-site.AcknowledgmentsThis study was carried out in SOLiD-EV project supported by NEDO (New Energy and Industrial Technology Development Organization).References Xuning Feng, Minggao Ouyang, Xiang Liu, Languang Lu, Yong Xi, Xiangming He, Energy Storage Materials 10 (2018) 246-267.