Symmetrical Li cells with Li 7La 3Zr 2O 12 (LLZO) solid electrolytes were used in this study. The chemical comparison of the LLZO cross-sections before and after cycling also shows the inhomogeneous distribution of Zr, La, and C after cycling as a result of lithium loss reaction near the lithium metal electrode.Ĭeramic and symmetrical Li–LLZO–Li cell preparation The chemical analysis of dendrites shows that they are mainly composed of Li 2CO 3 and Li xC y, and Li 2O. The results show inhomogeneous dissolution and deposition of lithium, leading to the formation of mossy and needle morphology dendrites. The set up and the experiments of this work are designed in a way to push the cell to its limits and to observe dissolution and deposition behavior and to observe dendrites. Energy dispersive spectroscopy (EDS) is also employed to conduct a chemical analysis. Videos are constructed using a multitude of subsequent SEM images that exhibit the morphological evolution during cycling. In this in situ study, scanning electron microscopy (SEM) is employed to monitor the behavior of Li surface and Li 7La 3Zr 2O 12 during cycling. This work focuses on observing the failure behavior of the cell containing LLZO electrolyte including conducting chemical analysis on the dendrites. In order to fully understand the behavior of garnet LLZO during cycling, further investigations are necessary. 14 solved the pore interconnectivity problem by modifying the grain boundaries. 13 correlated the battery short circuit to the interconnected pores in the LLZO. It is also found that lithium metal propagation through this electrolyte occurs through the grain boundaries 6. 5 indicated the electrochemical collapse of batteries that contain LLZO electrolytes at room temperature as a result of Li metal formation in the LLZO during cycling. Although LLZO satisfies the Monroe and Newman criteria and has exhibited promising properties, the failure of batteries that contain this electrolyte has been reported. One interesting electrolyte material for this application is Li 7La 3Zr 2O 12 (LLZO) because it has (a) a high voltage stability (up to 5 V), (b) high conductivity at room temperature (> 1 × 10 −4 S/cm), (c) low kinetic reactivity with Li, and (d) high shear modulus (approximately 55 GPa) 8, 9, 10, 11, 12. The failure and short circuit of batteries that contain ceramic electrolytes, however, have been reported 4, 5, 6, 7. Recently, the use of ceramics as solid electrolytes in all-solid Li metal batteries have attracted interest because of their high shear modulus. Monroe and Newman 3 have reported that a shear modulus that is twice that of Li can suppress dendrite growth. To overcome this limitation, one technique is the use of solid electrolytes with a high shear modulus to withstand perforations by dendrites and thus prevent battery short circuit. Lithium anodes, however, undergo dendrite formation during cycling that can increase the risk of battery short circuit 2. Metallic lithium is a potential anode material for high energy density Li-ion batteries because of its high capacity (3860 mAh g −1 for the reduced form) 1. Although the superior mechanical properties of LLZO make it an excellent electrolyte candidate for batteries, the further improvement of the electrochemical stabilization of the garnet–lithium metal interface is suggested. This work demonstrates the morphological and chemical evolution that occurs during cycling in a symmetrical Li–Li cell that contains LLZO. Moreover, the cross-section mapping comparison of the LLZO shows the inhomogeneous distribution of La, Zr, and C after cycling that was caused by lithium loss near the Li electrode and possible side reactions. The energy dispersive spectroscopy analyses of dendrites indicate the presence of Li, C, and O elements. Using the obtained SEM images, videos were created that show the inhomogeneous dissolution and deposition of lithium, which induce dendrite growth. In this work, in situ scanning electron microscopy (SEM) technique was employed to monitor the interface behavior between lithium metal and LLZO electrolyte during cycling with pressure. One promising candidate for this application is Li 7La 3Zr 2O 12 (LLZO) because it has excellent mechanical properties and chemical stability. In order to suppress dendrite growth, the use of electrolytes with a high shear modulus is suggested as an ionic conductive separator in batteries. Dendrite formation, which could cause a battery short circuit, occurs in batteries that contain lithium metal anodes.
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