Lithium primary batteries, such as Lithium Manganese Dioxide offer
high energy density, extremely long shelf life (two to three times that of Alkaline)
a wide operating temperature range, and excellent durability

With cell voltages of 3.0 to 3.6 volts, they provide
much higher energy density than Alkaline

Lithium primaries also come in a variety of sizes

Lithium Manganese Dioxide Li-MnO2 Coin Cell Battery

Lithium Manganese Dioxide Li-MnO2 Cylindrical Battery

Lithium Manganese Dioxide Li-MnO2 9 VOLT Battery