The Ryobi 18-Volt ONE+ High Capacity LITHIUM+ battery provides four times more run time, 4 times longer lasting charge and 20% lighter weight than Ni-Cd batteries. The fuel gauge lets you know the battery status before work begins. Lithium-ion batteries provide fade-free power for maximum performance throughout the charge.
https://www.amazon.com/Ryobi-P122-Capacity-Lithium-Batteries/dp/B015QIKGJK