enable the lithium metal anode with high rate capability. [1][2][3][4] While in LIBs with liquid electrolytes, lithium dendrite growth and low Coulombic efficiency prevent the use of lithium metal as an anode material, [3,[5][6][7][8][9][10][11] solid electrolytes (SEs) had been predicted to be able to block dendrite growth due to their high shear modulus. [12,13] In this context, Li 7 La 3 Zr 2 O 12 (LLZO) type garnet SEs [14] have attracted great attention as they combine high ionic conductivity with sufficient electrochemical stability against lithium metal, which prevents fast degradation and growth of a resistive interphase. [15,16] Nevertheless, certain issues at the lithium|solid electrolyte interface remain unsolved. [17,18] Lithium penetration through garnet-type SEs currently limits the possible charge rates. [19][20][21][22][23] In this context, it was found that good contact to a small reservoir of lithium metal is highly beneficial to prevent inhomogeneous lithium nucleation, which then reduces the lithium penetration susceptibility. [24] All previous results underline the need for sufficient and homogeneous contact between metal and SE during battery operation. Thus, it is of upmost importance for lithium metal solid-state battery development to prevent pore formation and growth at the anode interface during battery discharge. [24][25][26] Indeed, while the intrinsic charge transfer kinetics of the lithium|LLZO interface was found to be sufficiently fast for practical applications (R int < 2 Ωcm²), [26,27] recent work shows that the morphological instability of the (pure) lithium metal anode on solid electrolytes under anodic load is an inherent, fundamental problem that needs to be solved for battery designs that do not allow high operation pressures in the MPa range. [26,28] The morphological instability stems from the vacancy injection into lithium metal during anodic dissolution, which is a general phenomenon of parent metal electrodes. [29,30] It leads to contact loss and unwanted local current constriction during cell discharge. Therefore, transport of lithium in the lithium metal anode itself needs to be better understood and tuned to further increase the rate capability of cells with a lithium metal anode (i.e., to per-cycle areal capacities of 5 mAh cm −2 at current densities ranging to 10 mA cm −2 ). [31] However, the currently run, predominantly short-term lithium shuttling experiments onThe morphological instability of the lithium metal anode is the key factor restricting the rate capability of lithium metal solid state batteries. During lithium stripping, pore formation takes place at the interface due to the slow diffusion kinetics of vacancies in the lithium metal. The resulting current focusing increases the internal cell resistance and promotes fast lithium penetration. In this work, galvanostatic electrochemical impedance spectroscopy is used to investigate operando the morphological changes at the interface by analysis of the interface capacitances. Therewith, the effect of temper...