liquid electrolytes. ASSLBs exhibit overwhelming advantages as follows: 1) No electrolyte leakage. The most obvious advantage of ASSLBs is the avoidance of electrolyte leakage, and related issues such as fire hazard, electrical short circuit and corruption. In addition, ASSLBs do not need advance sealants, pressurizing electrolyte, and flame retardant failsafe. [1,2] 2) No thermal runaway. Thermal runaway will cause the rise of internal temperature, pressure, and vent of flammable gases in conventional LIBs, at a risk of explosion and shrapnel. [3,4] ASSLBs avoid the use of organic electrolytes and prevent the thermal runaway for a large extent. [5] 3) High resistance to lithium dendrite. The lithium dendrite may form during deposition process and penetrate through the separator, potentially cause a short circuit in conventional LIBs. [6] ASSLBs using solid electrolytes (SEs) with high shear modulus are expected to prevent/alleviate the dendrite penetration and extend the cell life. 4) Higher energy density. [7] The conventional LIBs are not suitable for the application of high voltage cathode and lithium metal anode because of narrow electrochemical window of liquid electrolytes, as well as failure in preventing lithium dendrite. ASSLBs facilitate the application of high voltage cathode materials and high energy density lithium metal anode, therefore increasing the energy density of the whole cell. Figure 1 shows the scheme of a typical ASSLB. Similar with conventional LIBs, the main components of ASSLB are cathode, SE, and anode. The distinctive component is SE, and its properties support the great advantages of ASSLBs. These properties include stability at ultrahigh and ultralow temperature, high mechanical strength, [8] wider electrochemical window (with passivation), and so on. [9-11] According to the category of SE, ASSLBs are divided into polymer-based, oxide-based, and sulfide-based systems, corresponding to the polymer, oxide, and sulfide electrolytes, respectively. Therein, oxide electrolytes exhibit moderate ionic conductivity, high shear modulus, and better stability with atmosphere and electrodes, are promising candidates for ASSLB. Specifically, oxide electrolytes are classified into LISICON (Li 14 ZnGe 4 O 16), NASICION (LiTi 2 (PO 4) 3), perovskite (Li 3x La 0.67-x □ 0.33-2x TiO 3), garnet (Li 3-7 LnMO 12 , Ln = Y, Pr, Nd, La, Sm-Lu, M = Zr, Sb, W, etc.), and so on based on their structure. Without reductive Ge, Ti elements in the composition, garnets are normally considered most promising among oxide electrolytes. [12,13] Garnet-type electrolytes in the formula of Li 3-7 Ln 3 M 2 O 12 , show a space group 3 Ia d. Lithium content ranges from 3 to 7 based on the substitution elements at Ln and M sites. [14,15] All-solid-state lithium batteries (ASSLBs) are considered to be the nextgeneration energy storage system, because of their overwhelming advantages in energy density and safety compared to conventional lithium ion batteries. Among various systems, garnet-based ASSLBs are one of the most promis...
