Ipad keeps shutting off when at 100%

My ipad 12.9 keeps shutting off when its at 100% battery and its hard to keep it from shutting off. When it shuts off and i go to restart it it says it is dead and needs plugged in but as soon as i plug it in it starts back up and then i get maybe 30 seconds then it shutdown. I need to figure out if it needs the battery replaced or whats wrong with it. Otherwise i guess i just cant charge it all the way up