## 3 Experimental Details
### Cell Fabrication and Tortuosity Measurement  
Figure 1a shows a schematic diagram of the electron-blocking cell used for the tortuosity analysis. When manufacturing the cell, stainless steel foil (SUS 444, 10 \(\upmu\)m, Woori-Science, Seoul, Republic of Korea) was used as the substrate, and lithium foil (99.9%, 10 \(\upmu\)m, MTI Corporation, Richmond, CA, USA) was used as the electrode material for the anode and cathode. When a potential difference was applied between the anode and cathode, the cell was suitable for analyzing the Li\({}^{+}\) transport pattern in the electrode composite because the electrolyte layer blocked the transport of electrons, and only the transport of ions occurred. The steady-state current (\(I_{\text{ss}}\)) was determined by applying a specific potential difference, \(\Delta\)E (=100 mV), to both ends of this cell (see Figure 1b). The resistance (\(\Delta E/I_{\text{ss}}\)) determined at this time was the total ion transport resistance (\(R_{\text{ion,total}}\)) inside the electron-blocking cell, which was the sum of the electrode composite resistance and electrolyte resistance of the two layers. Therefore, by calculating the resistance of the solid electrolyte layer using the ionic conductivity (\(\sigma_{\text{electrolyte}}\) = 0.174 S/m), thickness (\(I_{\text{SE}}\) = approximately 600 \(\upmu\)m), and area (\(A_{\text{SE}}\) = 1.33 cm\({}^{2}\)) of the solid electrolyte, and subtracting it from \(R_{\text{ion,cell}}\), the electrode composite resistance (\(R_{\text{ion,electrode}}\)) was calculated.  
\[R_{\text{ion,electrode}}=R_{\text{ion,total}}-\frac{2\times L_{\text{SE}}}{ \left(\sigma_{\text{electrolyte}}\cdot A_{\text{SE}}\right)} \tag{4}\]  
Then, the Li\({}^{+}\) conductivity (\(\sigma_{\text{eff}}\)) in the electrode composite was finally derived using the area (\(A_{\text{SE}}\)) and thickness of the electrode composite (\(I_{\text{electrode}}\)), and the tortuosity was determined by substituting this into Equation (2).  
In addition, the porosity (\(n\)) of the electrode was determined using the formula below, as a value representing the free volume, excluding the volume of the particles in the electrode composite.  
\[n=\frac{V_{\text{real}}-V_{\text{theo}}}{V_{\text{real}}} \tag{5}\]  
Here, the actual electrode volume (\(V_{\text{real}}\)) and theoretical volume of the constituent materials (\(V_{\text{theo}}\)) can be determined using the following equation.  
\[V_{\text{real}}=L_{\text{electrode}}\cdot A_{\text{electrode}} \tag{6}\]  
\[V_{\text{theo}}=\frac{m_{\text{AM}}}{\rho_{\text{AM}}}+\frac{m_{\text{SE}}}{ \rho_{\text{SE}}}+\frac{m_{\text{CA}}}{\rho_{\text{CA}}} \tag{7}\]  
where \(L_{\text{electrode}}\) and \(A_{\text{electrode}}\) represent the thickness and area of the electrode composite, respectively; \(m_{\text{AM}}\), \(m_{\text{SE}}\), and \(m_{\text{CA}}\) represent the masses of the active material, solid electrolyte, and conductive additive, respectively; and \(\rho_{\text{AM}}\), \(\rho_{\text{SE}}\), and \(\rho_{\text{CA}}\) represent the respective theoretical densities.  
All the electrochemical test cells were manufactured in an Ar-filled glove box (KK-011 AS-Extra (3 Port), Korea Kiyon, Seoul, Republic of Korea), and the electrochemical tests were performed using a potentiostat (BCS 810, Biologic, Seyssinet-Pariset, France).