In order to improve your phone's battery performance, there are a few things you can try:

1. In your phone's 'settings', go to 'battery' and turn on the 'battery saver' if you have one
2. Turn the 'bluetooth' , 'GPS' or 'Wifi ' off in 'Settings'  if you are not using it.
3. Remove any applications that you are not using. Open the 'Manage Applications' tool and tap the App that you want to manage. To delete the app, tap 'Uninstall'.
4. Turn down your screen's brightness and optimise time outs to conserve battery power. The screen is the largest battery draw on your smartphone, so these changes can make a considerable difference. To change brightness, go to your 'settings' and tap 'display' , then tap 'brightness'.