Batteries are made from many different types of materials. The chart below shows the energy to power ratio for different battery types (a range is shown for each battery). An increase in specific energy correlates with a decrease in specific power. Lithium-ion batteries have a clear advantage when optimized for both energy and power density. Most hybrid vehicles sold to date have had batteries made from nickel-metal-hydride. In the coming years, hybrid vehicles with lithium-ion batteries will appear in the marketplace.
Specific Energy and Specific Power by Type of Battery
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Note: Ni-Cd = nickel-cadmium; Ni-MH = nickel-metal-hydride; Na/NiCl2 = sodium/nickel chloride; LiM-Polymer = lithium-metal-polymer;
Li-ion = Lithium-ion; W/kg = watts per kilogram; Wh/kg = watt-hours per kilogram.
Source: International Energy Agency, Technology Roadmaps: Electric and Plug-in Hybrid Electric Vehicles, 2009, p. 12. (Original source: Johnson Control – SAFT 2005 and 2007.)
Supporting Information
The graph above shows super capacitors specific power ranging from 1 to 10,000 W/kg and specific energy ranging from 0 to 8 Wh/kg. Lead acid batteries specific power ranging from 1 to 500 W/kg and specific energy ranging from 10 to 30 Wh/kg. Lead acid spirally wound batteries specific power ranging from 100 to 5,000 W/kg and specific energy ranging from 10 to 25 Wh/kg. Nickel-cadmium batteries specific power ranging from 9 to 990 W/kg and specific energy ranging from 28 to 50 Wh/kg. Nickel-metal-hydride batteries specific power ranging from 20 to 2,000 and specific energy ranging from 48 to 82 Wh/kg. Sodium/nickel-chloride batteries specific power ranging from 9 to 300 W/kg and specific energy ranging from 80 to 120 Wh/kg. Lithium-metal-polymer batteries specific power ranging from 5 to 700 W/kg and specific energy ranging from 107 to 175 Wh/kg. Lithium-ion batteries specific power ranging from 7 to 9,000 and specific energy ranging from 42 to 180 Wh/kg.