21345
An initial capacity of 722 mA . h ( g Sn ) ( - 1 ) along with 405 mA . h ( g Sn ) ( - 1 ) retained after 150 deep cycles demonstrates the longest - cycling nano - Sn anode material for Na - ion batteries reported in the literature to date and marks a significant performance improvement for neat Sn material as alloy host for Na - ion chemistry .
 Chemical: Sn; Chemical: Sn; Chemical: Sn; Chemical: Na; Chemical: Sn; Chemical: Na
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: Sn; Chemical: Sn; Chemical: Sn; Chemical: Na; Chemical: Sn; Chemical: Na