FIB/SEM double-beam electron microscope is widely used in the preparation of material samples. Whether it is magic nano-paper cutting or nano-micro-columns for testing mechanics, it is inseparable from the precision processing of FIB. However, there are few reports on the use of FIB for in situ research. Recently, Ze You Science and Technology assisted Professor Huang Jianyu's team of Yanshan University to analyze the failure mechanism of sulfide solid electrolyte using in-situ FIB/SEM technology. The research result was published in Nano Letters, an internationally renowned academic journal, under the title of "Size dependent chemomechanical failure of sulfide solid electrolyte particles during electrochemical reaction with lithium. Professor Huang Jianyu, Professor Zhang Liqiang, Professor Tang Yongfu of Yanshan University and Professor Ding Feng of the Ulsan National Institute of Science and Technology of Korea are the co-corresponding authors of this article, and Zhao Jun, a doctoral student of the School of Materials of Yanshan University, and Zhao Chao, a doctoral student of the Ulsan National Institute of Science and Technology of Korea, are the co-first authors of this article.

Original Link: https://pubs.acs.org/doi/10.1021/acs.nanolett.1c04076

Figure 1 Experimental Method

Solid State Battery (SSB) is considered to be the future development direction of high energy density and high safety rechargeable energy storage devices, while solid electrolyte (SE) is the core component of solid state batteries. The Li10GeP2S12 solid-state electrolyte (LGPS) has a very high ionic conductivity, reaching 12 mS/cm, which is even higher than the organic liquid electrolytes used in commercial lithium-ion batteries. The ultra-high ionic conductivity makes LGPS a powerful candidate electrolyte in electric vehicle energy storage system, but the thermodynamic instability of LGPS to lithium metal greatly limits its wide application. At the same time, the sulfide electrolyte is extremely sensitive to air, and most of the current characterization is difficult to avoid short-term air contact, resulting in distortion of the results. In order to realize real-time dynamic observation of the failure process of LGPS electrolyte to lithium metal, Zeyou Technology and Mr. Huang's team jointly developed a FIB-TEM-glove box vacuum/inert gas protection transfer system, and constructed an in-situ solid-state battery system in FIB/SEM, making the in-situ results of sulfide electrolyte true and reliable.

fig. 2 vacuum/inert gas protection transfer system

this experiment uses the battery material solution of zeyou technology to transfer the air-sensitive lithium metal and sulfide solid electrolyte Li10GeP2S12(LGPS) from the glove box to TEM and FIB for sample characterization and in-situ experiments. First utilizing the FIB vacuum transfer system (PicoFemto®FN01-ST-T) The sample is transferred to the FIB, and then the nano-probe station conducts an energization experiment on the sample. With the operation of the Li-LGPS-In micron all-solid-state battery, the LGPS solid-state electrolyte gradually failed to crack until it was completely pulverized. Through a large number of in-situ experiments, the researchers surprisingly found that reducing the size of the solid electrolyte will effectively reduce the powder failure of the solid electrolyte. In order to further analyze this size effect, the researchers used the solid electrolyte to vacuum transfer the sample rod (PicoFemto®ZT-FD-01) is transferred to the transmission electron mirror, and further analysis of the phase before and after the sulfide electrolyte reaction can be obtained. The experimental results show that the electrochemical reaction between the sulfide solid electrolyte and lithium metal is the main reason for the cracking of the electrolyte, and the size effect is due to the balance between the elastic energy released during the reaction of lithium metal and LGPS and the surface energy and other forms of energy generated by particle breakage. This size effect can be used to reduce the chemical-mechanical failure of LGPS electrolyte, that is, to reduce the particle size of LGPS to less than 1 micron, which can effectively avoid the pulverization of LGPS electrolyte. This conclusion provides a new size screening approach for the design of all-solid-state batteries.

Figure 3 Experimental device diagram, LGPS electrolyte failure process and reaction products

Figure 4 Size effect of LGPS particles in the reaction process with lithium metal

Figure 5 Phase analysis of air sensitive materials before and after LGPS reaction