They do. Lithium ion has a 3.7V nominal voltage compared to the 1.5V of alkaline and 1.2V of NiMH, and so liions in the AA format are called 14500s (14mm diameter 50mm length) and 11500s in AAA format. There's also liion AAs with voltage regulators to provide 1.5V that often have a USB micro B or C port on them