According to the manual, the TI-84 Silver Edition is powered by a replaceable, rechargeable, and can be powered/recharged from a USB supply.
So why do you want to put in different batteries?
From its manual:
Use one of the following options to charge the battery in the TI-84 Plus C graphing calculator:
• Connect the graphing calculator to a computer using a USB computer cable.
• Connect to a wall outlet using a TI wall adapter (may be sold separately).
• Place the graphing calculator in a TI-84 Plus C Charging Station.
The amount of time required to fully charge the battery may vary, but charging normally takes four to
six hours. It is not necessary to remove the TI Rechargeable Battery from the graphing calculator to
recharge it. The graphing calculator operates normally while it is attached to a charging source