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High energy, lightweight, batteries

Flight Power " EVO 20" Lithium Polymer battery

from http://www.hobby-lobby.com/flightpower.htm

Lithium Sulphide battery from http://www.sionpower.com/pdf/sion_product_spec.pdf

High energy density batteries

We consider the two top battery technologies: the latest Lithium Polymer technology, and the up and coming Lithium Sulphide battery technology.

Information from http://www.hobby-lobby.com/flightpower.htm for the Flight Power " EVO 20" series of LiPo batteries.

• Each cell has a voltage of 3.7 volts.
• The specific energy density is 505 KJ / Kg. Compare this with the specific energy of 11,000 KJ / Kg for a gasoline MOGAS engine.
• All Flight Power EVO 20 cell names start with FP
• Configuration terminology: S = series, P = parallel, so 3S2P means two parallel (2P) sets of three series (3S)   connected cells
• At peak current operation, each cell will be discharged in three minutes.

We conclude that electric flight using LiPo batteries  is a short duration activity.

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From http://www.sionpower.com

Sion Power has achieved breakthrough results by a unique merging of sulfur and lithium chemistries, to develop Li-STM technology. Sion Power uses the well-known high electrochemical potential of lithium and combines it with sulfur, to attain a  superior rechargeable performance. Theoretical specific energy is in excess of 2,500 watt hours per kilogram and energy density exceeded 2,600 watt hours per litre.

By using the powerful combination of the elements, lithium and sulfur, in the most efficient geometry, a thin-film sandwich, Sion Power has created a rechargeable battery with advanced characteristics. Sion Power's Li-S technology provides rechargeable cells with a specific energy of over 350 Wh/kg, which is 50% greater than the currently commercially available rechargeable battery technologies. Over 600 Wh/kg in specific energy and 600 Wh/l in energy density, are achievable in the near future.

This unique chemistry can be designed to deliver high energy, high power, or, a combination, depending upon the requirements of the application. For example, in high power applications like power tools and appliances, Li-S has nearly the same rate capability as nickel cadmium and nickel metal hydride  but has only one-third to one-fourth the weight. Furthermore, Sion Power cells have a voltage of 2.1 volts, which  is ideal for the next generation of electronics, expected to operate at 2 volts or less. For higher voltages, the cells can be easily connected, in series.

Lithium Sulphur technology:

Li-STM is both cost effective and cost competitive, when compared to other battery systems Battery costs are driven primarily by the material content and yield. As sulfur is much less expensive than the typical components of other battery systems, the Li-STM technology starts with a lower material cost than lithium-ion or lithium-polymer batteries. Manufacturing techniques for Li-S batteries are very similar to those used in other battery chemistries.

Ease of Production:

Manufacturing of Li-STM cells is no more difficult than manufacturing lithium-ion liquid, or, lithium-ion polymer cells. The anode and cathode of Li-STM cells are thin materials, substantially similar in thickness and tensile strength to those of lithium-ion. Standard lithium-ion winders can be used with little or  no modifications. Prismatic and cylindrical form factors can be produced from the same anode and cathode raw materials.

The Company's technology is secured by over 51 US issued patents and over 48 applications pending worldwide, protecting various enabling aspects of Sion Power's intellectual property. Sion Power’s Li-S is the next rechargeable power source for a wide variety of applications, including unmanned vehicle systems, military communications, cell phones, notebook pcs and electric vehicles.

from http://www.sionpower.com/pdf/sion_product_spec.pdf

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From Electronics Weekly, 16 May 07

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