Most future batteries function wonderfully in a theoretical world, but many fail to meet the eight basic requirement of the so-called Octagon Battery. Short cycle life and limited load currents often prevent commercialization of the breakthroughs. While futuristic batteries may find a niche market, many never step outside the lab and see the light of day, not to mention advance to power the electric powertrain. This touches with emotions and is as far as the battery can go.

Chemistry Lithium-air Lithium-metal Solid-state Lithium Lithium-sulfur
Type Air cathode with lithium anode Lithium anode; graphite cathode Lithium anode; polymer separator Lithium anode; sulfur cathode Carbon anode; diverse cathodes
Voltage per cell 1.70–3.20V 3.60V 3.60V 2.10V 3.6V
Specific Energy 13kWh/kg theoretical) 300Wh/kg 300Wh/kg (est.) 500Wh/kg or less 90Wh/kg
Charging Unknown Rapid charge Rapid charge 0.2C (5h) Unknown
Discharging Low power; inferior when cold High power band Poor conductivity when cold High power (2,500W/kg) Unknown
Cycle life 50 cycles in labs 2,500 100, prototypes 50, disputed 50 typical
Packaging Not defined Not defined Prismatic Not defined Not defined
Safety Unknown Needs improvement Needs improvement Protection circuit required Safe; shipment by air possible
History Started in 1970s; renewed interest in the 2000s. R&D by IBM MIT, UC, etc. Produced in the 1980s by Moli Energy; caused safety recall Similar to Li-polymer that started in 1970 New technology; R&D by Oxis Energy, Bosch and others. Ignored in the 1980s in favor
of lithium; has renewed interest
Failure modes Lithium peroxide film stops electron movement with use. Air impurity causes damage. Dendrite growth causes electric short with usage Dendrite growth causes electric short; poor low temperature. performance Sulfur degrades with cycling; unstable when hot, poor conductivity Little research in this area
Applications Not defined; potential for EV EV, industrial and portable uses EES, wheeled mobility; also talk about EV Solar-powered airplane flight in August 2008 Energy storage
Comments Borrowed from “breathing” zinc-air and fuel cell concept Good capacity, fast charge and high power keep interest high Similar to lithium-metal; may be ready by 2020; EVs in 2025 May succeed Li-ion due to lower cost and higher capacity Low cost in par with lead acid. Can be fully discharged.

Table 1: Summary of most common future batteries. Readings are estimated and may vary with different versions and newer developments. More information on BU-212: Future Batteries. Readings are estimated and may vary with newest development.