Critical Current Densities for Short-Circuiting of Solid-State Electrolytes

The cubic phase Li₇La₃Zr₂O₁₂ (LLZ) exhibits Li⁺ conductivity on the order of 10^-4 S cm^-1 at room temperature and has sufficient stability even in contact with molten Li¹⁾. Additionally, its shear modulus is several times greater than those of sulfide solid electrolyte materials²⁾, and it is thus expected to act as a promising solid-state electrolyte for preventing dendrite growth of Li metal. However, it has been reported that repeated charging/discharging of Li metal anodes causes short circuits, even with LLZ. Similar results were reported by subsequent researchers, and it was gradually realized that the short-circuit problem was more difficult to solve than originally thought.<br/>Various models of the short-circuit mechanism of LLZ have been discussed^3,4), but there is no experimental confirmation of what determines the critical current density (CCD) that induces shorts. This is partly because Li voids are easily formed at the Li/LLZ interface, making it difficult to compare the CCD values under fair conditions. In the present study, the CCD was measured by keeping the Li/LLZ interface constant. The temperature dependence of the CCD was also clarified, and the short-circuit mechanism was discussed based on the activation energy values of the CCD.<br/><br/><b>Acknowledgment</b><b>s</b><br/>This work was supported by JSPS KAKENHI Grant Number JP22H04611 (Grant-in-Aid for Scientific Research on Innovative Areas “Interface IONICS”), JP 22H02178, and JST GteX Grant Number JPMJGX23S5.<br/><br/><b>References</b><br/>1) R. Murugan, V. Thangadurai, and W. Weppner, <i>Angew. Chem. Int. Ed.</i><i>,</i> <b>46,</b> 7778–7781 (2007).<br/>2) A. Sakuda, A. Hayashi, Y. Takigawa, K. Higashi, and M. Tatsumisago, <i>J. Ceram. Soc., Jpn.,</i> <b>121,</b> 946–949 (2013).<br/>3) T. Krauskopf, F. H. Richter, W. G. Zeier, and J. Janek, <i>Chem. Rev.,</i> <b>120,</b> 7745–7794 (2020).<br/>4) M. Motoyama, Y. Tanaka, T. Yamamoto, N. Tsuchimine, S. Kobayashi, and Y. Iriyama, <i>ACS Appl</i><i>.</i><i> Energy Mater</i><i>.,</i> <b>2,</b> 6720-6731 (2019).