Battery is made up by combination of small cells. Cells getting destroy with time we can't stop it because its made up chemical and chemical reaction gives energy.So if your battery is not charging means you need to change battery there is no other option.You can find out what is inside the battery.
https://www.google.co.in/search?q=inside+nokia+battery&espv=2&biw=1024&bih=643&source=lnms&tbm=isch&sa=X&ei=0dGqVI2VO4uwuASrnoLgAw&ved=0CAYQ_AUoAQ#tbm=isch&q=inside+mobile+battery&facrc=_&imgdii=_&imgrc=MI34qV_f26ZNXM%253A%3B9acnDQHxTHaeLM%3Bhttp%253A%252F%252Fwww.physicscentral.com%252Fexplore%252Faction%252Fimages%252Fbattery_pack_zdnet.jpg%3Bhttp%253A%252F%252Fwww.physicscentral.com%252Fexplore%252Faction%252Flithium.cfm%3B350%3B315