Terms for Batteries-Energy Density Definition:the amount of energy stored in a given system or region of space per unit volume or weight. Generally,with the same volume,lithium-ion batteries have an energy density that is 2.5 times of Ni-Cd batteries,and 1.8 times of Ni-MH batteries. 400 Li metal Li ion ('unsafe') 300 PLiON 200 洗 K6u3 Ni-Cd 100 Lead- acid Lighter weight 0 50 100 150 200 250 Energy density(W h kg) 6
6 • Definition: the amount of energy stored in a given system or region of space per unit volume or weight. • Generally, with the same volume, lithium-ion batteries have an energy density that is 2.5 times of Ni-Cd batteries, and 1.8 times of Ni-MH batteries. Terms for Batteries - Energy Density
Terms for Batteries Cycle Life 9 Definition:the number of full charge-discharge cycles when the capacity of the batteries reaches 75%of the initial value. The cycle life is related to the testing conditions. For lithium-ion batteries,when tested at 1 C and 25 C,their cycle life is usually 300-500,maximally 800-1000. 900 SnO@Carbon B 0”3 SnO2 Theoretical Capecity of Graphite 600 300 0 20 40 60 80 100 Cycle Number Chem.Mater..2009,21,2868-2874 7
7 Terms for Batteries – Cycle Life • Definition: the number of full charge-discharge cycles when the capacity of the batteries reaches 75% of the initial value. • The cycle life is related to the testing conditions. • For lithium-ion batteries, when tested at 1 C and 25 oC, their cycle life is usually 300 – 500, maximally 800 – 1000. Chem. Mater. 2009, 21, 2868–2874