The DC polarization method was applied to determine the electronic conductivity by applying different constant bias voltages over 600 s and obtaining the corresponding steady-state current. Linear sweep voltammetry was conducted at 0.1 mV/s to investigate the electrochemical stability using the following cell configuration: Na3Sn|NPS|chloride SSE composite, the mass ratio of each layer was 50 mg: 100 mg: 120 mg, respectively. Each sample powder was pressed in a 12 mm diameter PEEK sleeve using a manual screw press (rhd instruments GmbH) at 13 KN (100 Mpa) for 0.5 h. The chloride SSE composite consisted of 83.3 wt. % chloride SSE and 16.7 wt. % Carbon SuperP is an electron conductive additive, ensuring electronic transfer within the composite. DC polarization and linear sweep voltammetry (LSV) measurements are performed under external pressure of 70 Mpa and at room temperature.