Sodium-sulfur flow battery and battery stack

The invention relates to a sodium-sulfur flow battery and a battery stack, the sodium-sulfur flow battery comprises a negative electrode flow channel, a positive electrode flow channel and a ceramic electrolyte membrane between the negative electrode flow channel and the positive electrode flow channel, and also comprises a porous cathode membrane arranged between the ceramic electrolyte membrane and the positive electrode flow channel; and the porous safety membrane is arranged between the negative electrode flow channel and the ceramic electrolyte membrane. According to the sodium-sulfur flow battery disclosed by the invention, a battery stack provides a positive conductive network through a porous cathode film; according to the porous safety membrane, under the condition that the ceramic electrolyte membrane is broken, the sodium sulfide solid generated in the pores of the porous safety membrane is used for blocking the crack of the ceramic electrolyte membrane, so that the safety of the battery is fundame