14826
Furthermore , without the use of catalysts , the battery shows a low discharge / charge potential gap of less than 50 mV at a modest current density , which is the lowest one that has ever been reported in metal - oxygen batteries .
 Chemical: metal - oxygen
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: metal - oxygen