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 ______      ___     __   _     _____    _    _   
|      \\   / _ \\  | || | ||  |  ___|| | \  / || 
|  --  //  / //\ \\ | '--' ||  | ||__   |  \/  || 
|  --  \\ |  ___  ||| .--. ||  | ||__   | .  . || 
|______// |_||  |_|||_|| |_||  |_____|| |_|\/|_|| 
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Text this: Template-free synthesis of VO2 hollow microspheres with various interiors and their conversion into V2O5 for lithium-ion batteries