A pack of 4 Energizer Ultimate Lithium AA batteries will cost you $25.61 ($6.40 each!) on amazon.com, compare that to a 20 pack of their alkaline batteries for $10.91($0.55 each). The box claims 9x better battery life, but they are almost 12x more expensive!
Is it worth it?
The answer is simple: it depends.
Although Lithium and Alkaline AA batteries are both 1.5 volts, and hold roughly 1500 mAh charge, Lithium batteries are more functional in many ways. Lithium (single use primary lithium, not to be confused with the rechargeable lithium ion batteries in your laptop) batteries are lighter and more efficient than alkaline batteries. They provide more consistent current, keep their voltage high under heavier use, and function better in low temperatures. They also handle pulses of current better which is important for Bluetooth and WiFi applications. The obvious advantages Alkaline batteries have are in cost and flammability, FAA regulations prohibit shipping loose Lithium batteries by air because once ignited the batteries are almost impossible to extinguish. A less obvious disadvantage of Lithium will mainly be of concern for tinkerers and the chronically unlucky, the higher amount of current provided by lithium batteries can lead to more catastrophic short circuits.
The case for alkaline batteries looks pretty grim, but they do have their place in the world. Many applications simply don’t require a high performance battery. Devices like a television remote control and that backup flashlight in your kitchen drawer spend the vast majority of their time powered down and will reap minimal benefits from higher priced performance batteries.
If your device is always on, uses wireless communications, operates in low temperatures, or has high draw components like a flash or LCD, splurge on lithium batteries. It’s worth it.