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Posted on January 27, 2009 by  &  with 3 Comments

Ultrathin lithium rechargeable battery

Front Edge Technology Inc (FET) manufactures and markets next-generation, ultra-thin rechargeable batteries for card-type applications.
The NanoEnergy® batteries are thinner than a piece of paper and when embedded in micro devices such as smart cards and portable sensors, act as an autonomous power source enabling new functions which greatly add to their value.
The batteries are composed of solid-state thin films with active components: Electrolyte which is Lithium Phosphorus Oxynitride (LiPON) developed by Oak Ridge National Laboratories (ORNL) and licensed to FET; cathode material of LiCoO2, and the anode is Lithium.
Construction of a thin-film battery. (Source: John Bates, Oak Ridge Micro-Energy).
FET is working with its customers to develop next generation self-powered micro systems and with this in mind they are building a NanoEnergy production line with initially modest designed annual capacity of 200,000 pieces of 1-mAh NanoEnergy. As yet this uses a thin film process which in not printed technology. The production line includes six industrial-scaled, in-line vacuum deposition systems, as well as other supporting equipment. Samples of NanoEnergy have already been produced by this production line and delivered to FET's customers for their product developments.
This miniature power source is designed for space limited micro devices such as smart cards, portable sensors, and RFID tags say the company. IDTechEx would add many energy harvesting applications, back up power supplies etc to that. The following figure shows a NanoEnergy powering a blue LED. The insert is a cross-sectional scanning electron microscope image of a NanoEnergy.
The picture shows a NanoEnergy® powering a blue LED. Inset shows sectional scanning electron microscope image
Source: Front Edge Technology
The battery is exceptionally thin at 0.05 mm (0.002 inch) including the package and is hermetically sealed against gas leakage. Like other thin batteries, it can be bent and twisted without damage. There can be environmental concerns with lithium but the company says the battery is all solid-state, using ceramic electrolyte LiPON developed by Oak Ridge National Laboratories. It contains no liquid or environmental hazardous material.
Laminar construction usually means fast recharging time and this battery is no exception. It can be charged to 70% of rated capacity in 2 minutes and discharged at rates of more than 10 C, greatly out-performing manganese dioxide zinc laminar batteries but at a higher price, we suspect. Self discharge is low at less than 5% per year. When charged at 4.2 V and discharged at 1 mA to 3.0 V, the battery has less than 10% capacity loss over 1,000 charge/discharge cycles.
Perhaps the company will be able to commit to larger numbers of cycles in future as is demanded by some long life applications in energy harvesting etc. For example, Infinite Power Solutions can cope with over 10000 deep recharges with their laminar lithium batteries and about one million shallow recharges.
Like some other laminar lithium batteries, there is no chance of flammability because so little lithium is involved. The company says, "The battery contains no toxic liquid electrolyte. There is no source for out-gassing or explosion. The small amount of Lithium metal in the battery does not cause fire even if the hermetic seal is broken."
NanoEnergy® can be customized to fit specific size requirements. The following are two typical battery sizes:
1. 20 mm x 25 mm, with thickness of 0.1 mm (Capacity of 0.1 mAh ) to 0.3 mm (Capacity of 1 mAh)
2. 42 mm x 25 mm, with thickness of 0.1 mm (Capacity of 0.5 mAh) to 0.4 mm (Capacity of 5 mAh)
Electrical connections are typically metal foils with 10 mm long, 2 mm wide and 0.1 mm thick.
Top image: The world's thinnest rechargeable battery claim FET. (Source FET).

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Posted on: January 27, 2009

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