14542
In this review , we begin with a brief discussion of the operating principles and scientific / technical challenges faced by the development of lithium / sulfur cells .
 Chemical: lithium; Chemical: sulfur
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: lithium; Chemical: sulfur