6 hours to full the battery why this issu in my j7 prime ?who wait 6 hours plz tell me how its solve

j7 prime me charging slow horehi hee,battery full hone keliye kam se kam 3 hours lagjate,itna time kon wait karega,battery backup ki bat kare to achha nehi he....yar kuch batao jise charging speed hoga or battery backup b jyada time tak rakhega..????...