Tuesday, April 24, 2012

Energy Harvesting from Ambient Electromagnetic Waves

Prof. Prabaharan and his team of students have developed ways to harvest energy from the ambient electromagnetic (EM) radiation and converting it into a useful electrical energy stored across a power buffer media the so-called Electrochemical Supercapacitors or Ultracapacitors.

By definition, Energy Harvesting is in a broader perspective called Scavenging energy from ambient atmosphere. In a nutshell, it is the process of converting energy from the environment into a usable power for a device to sustain its electrical operation and/or store the energy for a later use via Li-Ion batteries. Hence, one can address a self suitainability of portable electronics (IPads for instance), celluar mobile phones in which portability of electrical energy is a paramount issue for a longer usage.

This novel appraoch uses the tapping, converting and storage of energy from the EM radiation from its feeble peak-to-peak potential into a usable EMF which is storaged temporarily in a buffer storage media called Supercapacitors (more about Supercapacitors, please read my other pages in my blogg here).

Peer reviewed Publication: Performance Comparison of Data Compression Algorithms for Environmental  Monitoring Wireless  Sensor Networks,  J. G. Kolo, K. P. Seng, L.-M. Ang, S.R.S. Prabaharan in Int. J. of Computer Applications in Technology (In press, 2012).
Note: More details will be uploaded sooon.

Lithium Air Secondary Batteries

Prof. Prabaharan has embarked on advanced Li/Air battery research since August 2011 with support from MOHE's research funding and continued his Li/Air research in IMRAM, Japan during his visiting professorship (September 2011 until March 2012). 

Li-air cell reactions are often hyped as the technological heir to Li-Ion batteries as well. Li-air battery system may be thought of as primary as well as secondary version where the latter can be recharged. Hence, in pursuit of next generation energy storage systems, Li-air systems may pose a great challenge to Li-Ion batteries (as the energy density of the latter is now approaching its theoretical limit set by the energies of cathode and anode materials used).

In lithium-air batteries, lithium metal anode (protected or unprotected) is electrochemically coupled to atmospheric oxygen through an air cathode as shown in the schematic below:
                                                   Figure 1: Schemtics of Li/Air Battery

                                        Figure 2: Stainless steel Lithium/air Cell housing

Our proprietary Lithium air cell housing designed by Prabaharan et al to vent the air during cell cycling is shown in figure 2.

           Figure 3: Li/Air Experimental Set-up in IMRAM (developed by Prabaharan et al, 2011)

This collaboration has emerged with a big success on developing three important aspects:
1) A specifically designed SS Electrochemical Cell housing for Li/Air test cells (see Figure 2 above);
2) Development of Gas Diffusion Layer for Air Cathodes;
3) Protected Lithium Anode;

As part of his research on air cathode development, Prof. Prabaharan and his team comprising  Dr Malathi, Dr Sathish, (IMRAM) and his Japanese counter part Prof. Kawamura, Prof. Homa and Dr Kuwata have developed air cathode with different cathode including the N-doped graphene.

Some of the research components of this work are collaborated with my Indian counterpart, Dr Michael from SSN College of Engineering, Chennai, India.
Prof. Prabaharan's recent ACS invited talk in San Diego, USA (March 2012) highlighted his recent findings on Li/Air batteries.  His important findings on Air cathode and protected lithium anodes are under publication in high impact journals.

His group has developed a pouch type Li/air cell which is capable of powering LCD clocks and yet rechargeable. The snopshot is given below:

Friday, June 10, 2011

3.2F Supercapacitor with 99.3 mohm Developed by Prabaharan et al.,

Cyclic Voltammetry Curve showing a perfect rectangular shape of the supercap deveoped illustrating the pure double layer properties governed by a pure Electrostatic mechanism across the interface between electrode and electrolyte.Green technology is much sought for various envrionmental issues. Departure from conventional fossil fuel to alternative must be clean and yet signifies the GREEN. We have developed a new supercapacitor with 100% green materials and a special non-aqueous electrolyte having a proprietary activated carbon (> 3000 m2/g)mixed with superconductive (XL6)additive. The cost effective GREEN capacitor may be offered for almost 30% less cost than the competitor brands. The supercapacitor was tested in LED flash systems and other green applications. A special process for electrode coating has been developed which helps reduce the ESR much lower than expected.

Any further details can be had with this blog owner. The above CV explains how good is our supercap. without any electrode pretreatment process. For confidential reasons, CV with pretreated electrode coating is not shown here.

Tuesday, June 7, 2011

A New type of a simple TWIN LED flash system with a Supercapacitor Developed by Prabaharan et al.,

Photograph: TWO LED flash demonstration showing the brightness during flashing due to Supercapacitor.

SMD compatible PCB designed for TWIN LED flash system developed

Prabaharan et al., have designed and developed a new type of twin LED flash system which incorporates a supercapacitor (0.73 F, 100mOhm) which plays a dual role as burst of power delivery medium as well as an energy buffer to help extend life of rechargeable battery by handling the pulse power required by the smart phones and digital cameras. Approaches used were designed by prototype simulation circuit using Cadence Orcad Capture, fabrication of hardware, testing phase employing SMD compatible PCB designed in-house. Here we demonstrate the importance of a supercapacitor which acts as a second power reservoir and buffer to handle the pulsed power needed in µs to ms duration during light flash.