TEMPERATURE INCREASING METHOD FOR SODIUM-SULFUR BATTERY

A temperature increasing method for a sodium-sulfur battery includes three or more temperature gradients, and inflection points of 90±5°C and 150±5°C at which the temperature gradient changes, and the temperature gradient in a section from 90±5°C to 150±5°C is 5°C/h or less, whereby it is possible to increase a temperature of the sodium-sulfur battery quickly without affecting the quality of the sodium-sulfur battery.