What is Nano Batteries Technologies and its details explanation l Nano phosphate technology l Nano pore battery technology l Nano structured battery l Development and Construction of the Battery l Experimental and Result l Anode l Cathode l Electrolyte l

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Introduction

As Nano Batteries technology progresses there is an increasing demand to shrink bio-medical electronic devices to the micro and Nano scale. These Nano scale biomedical devices will be need bio compatible energy sources to provide power on the demand. Thus development of the micro and Nano batteries is of the great interest to the bio-medical instrumentation community. Ideally the Nano battery is envisioned as the single battery cell with Nano scale dimensions that can be integrated on to the Nano device. However, given the current status of the technology, it is difficult to fabricate the single Nano battery with an assured reliable performance.

Thus the first logical step to be achieve this goal is to develop the macro battery with an array of micro & Nano cells. Each cell is itself a battery and they are the electrically connected in the parallel so that the total power drawn from this device is the sum of the power from this array of micro & Nano cells. Once this battery is the fabricated then bio compatible coatings need to be developed to the package Nano battery systems so that they may be the implanted safely in the biological systems.

The Nano battery technology system developed by the group also has the following advantages. While conventional batteries are the typically heavy and this limits their use in a number of the applications, Nano batteries are lightweight and hence the versatile. Runaway thermal failure is eliminated since each Nano battery cell is electrically isolated from the rest of the Nano battery cells. Also, since the volume of the each cell is small, any thermal runaway reaction is the contained in a Nano cell and will be produce limited heat that the battery can be easily withstand.

Abstract

Future of the bio-medical devices with the dimensions in the Nano scale region will be need independent the energy sources to power them. Lithium ion micro and Nano batteries are the excellent candidates for these power sources. Our proposed Nano battery design ensures that these batteries remain lightweight and the safe with fast rechargeable times. We have used femtosecond laser for the precision machining. Intense electric fields produced by the laser beam induces electrical breakdown due to the avalanche ionization.

For the femtosecond pulses, this breakdown threshold remains fairly deterministic thereby allowing the use of the fem to second lasers for micro and the Nano-machining. The Nano battery consisted of an anode, cathode and separator. The anode was made of graphite or molybdenum oxide while the cathode was made of LiCoO2. The separator was a Kempton membrane with an array of n x n holes micro- or Nano-scale holes machined into it which were then filled with Li-based electrolyte.

Development and Construction of the Battery

All the materials are susceptible to damage by a focused laser beam when the induced electric field produced by the laser beam is a comparable to the Coulomb field the electron sees in the proximity of the atomic nucleus leading on the creation of an avalanche process for the free electrons. This process also occurs in the transparent materials which become an opaque when the free electron density approaches the critical density for that particular the light.

It is the important to note that this optical breakdown has a nonlinear dependence on the intensity and this allows for the damage to be restricted to the sub diffraction limit by the “thresholding” allowing the fabrication of the Nano scale features Squire et al 1991 Jogelkar et al 2003. Though, optically induced dielectric breakdown the scales as t1/2, where it is the pulse width for the pulse durations longer than 10 ps, the damage threshold remains fairly constant and deterministic for the shorter pulses Stuart et al 1996.

For the ultra-short pulses, polarization of the beam also plays an important part. For the linear polarization, a machined hole becomes the narrow groove in the direction of the polarized beam. This effect was the pronounced at the low pulse energy close to the threshold of the material Venkatakrishnan et al 2002. At low energies, only the central part of the beam has the enough energy to ablate the material and thus, in this energy regime.

Basic design of a nanobattery

Experimental and Result

Ferritins were the purified through size exclusion chromatography and de mineralized through a reduction process to be make Apo ferritin, ferritins without the core material. Co ferritin was the synthesized by the adding Co2+ to Apo ferritin in the presence of the H2O2.11 similarly, ferritins can be the reconstituted with the other metallic cores. Ferritin arrays were are fabricated using the cat ionized Ferritin, enabling a strong electrostatic attraction to the negatively charged Si substrate. The spin self-assembly (SSA) deposition method12 was the used to produce Ferritin arrays on the various substrates.

Depositing the successive layers of the ferritins on silicon substrates formed of the arrays, redox charge transfer chains. The total output of the current and voltage can be tailored by the selecting either serial & parallel connection of the pairs. Examination of the layer structure was the accomplished using the scanning probe microscopy (SPM), while the magnetic properties of the ferritin with the metallic cores allowed a magnetic force microscopy (MFM) tip to be the used. SPM images show the 2-D ferritin arrays to be smooth and the uniform, suggesting that the SSA deposition method will be produce fast, reliable arrays for the bio-Nano battery technologies.

Stability tests of the Co ferritin indicate that most of the cobalt remains bound to the Co ferritin (>90%) for the extended time periods, demonstrating the stability of the Co (OH) 2 mineral phase within a ferritin interior. Figure shows the reduction of the Co3+ to Co2+ in Co ferritin at the 350 nm. The absorbance decreases with the reduction of the cobalt core as the ascorbic acid a 2 electron donor is the added, until it becomes stable when all the Co3+-ferritin is reduced to the Co2+-ferritin. This result shows that 1.85 Co3+ are the reduced per ascorbic acid added.

An electrochemical cell was the also used for kilometric reduction measurements, showing that 1.10 e/Co was the taken up during the electrolysis of Co3+-ferritin. The reduction equilibrium and the reduction kinetics of the both Co ferritin and MN ferritin were the also examined. Preliminary results showed that an equilibrium condition between the MII and the MIII core material was the achieved. The reduction of kinetics show a reduction of core material with the time. Results indicate that the manganese reduces much be faster than the cobalt.

There are some technologies which are mainly used in Nano batteries

  1. Nano phosphate technology
  2. Nano pore battery technology
  3. Lithium ion batteries (using lithium titan ate)

1. Nano phosphate technology

The overall performance and the reliability of an advanced battery system depends on largely on the chemistry used in the cell.Nanophosphate should not be the confused with the standard lithium iron phosphate (LFP), which is has the lower rate capability and Power.Nanophosphate is the lithium ion battery cathode founded by the professor yet Ming chain and his group.Nanophosphate particles are the divided into two groups i.e. Primary and the secondary.

Conversely, the chemical reactions can be created in the monophosphate technology increase the cathode surface area with the electrolyte, which are allows for the faster lithium insertion and thus more power. At the same time, however, all of the bulk volume is still used to store the energy. As shown in given figure another significant feature of the monophosphate technology is the consistent power capability over a wide range of the states of charge (SOC). Most of the battery technologies have significantly lower power capability at the low SOC.

Nano phosphate technology

2. Nano pore battery technology

Now, researchers have managed to the restructure the materials in a Nano battery, then bundle lots of these individual batteries into the larger device. Previously, researchers had been developed 3D nanostructured batteries by the placing two electrodes within the Nano pore made of the anodic aluminium oxide and using ultrathin electrical insulating material to the separate them.

While this system had improved power and the energy density, use of such thin electrical insulators limits charge retention and the requires complex circuits to shift the current between them it’s difficult to retain the benefits of the 3D Nano architecture due to the spatial constraints of the material. Instead of the using wired circuits, liquid solutions of the electrically conductive ions electrolytes have been used to the connect battery circuits.

However, Nano batteries that use electrolytes have been shown low charge storage; moreover, when used in the conjunction with 3D structures, uneven ion concentration gradients resulted in the uneven current densities. Recently, researchers have been overcome these limitations through the design of the battery that more effectively combines several components. The new battery is composed of the parallel array of the Nano batteries.

Nano pore battery technology

3. Nano structured battery

The Lead acid battery technology, conventional Li-ion technology etc. are the failed to meet the requirements like extended of the life, safety, remote UPS (Uninterruptable Power Supply) applications. And these technologies can’t be tolerate the abusive conditions like short circuit, over recharge, exposure to the extremely high & low temperature, over the discharge.

Altair Nano Company developed by battery using nanotechnology which eliminates some drawbacks of the conventional batteries. Altair Nano’s Li-ion technology is the different than the commonly used Li-ion technology. They replaced the graphite material which is used in the conventional batteries with the Nano-structured lithium titan ate.

Nano structured battery

Nano batteries are generally described by three sections

1. Anode
2.Cathode
3.Electrolyte

In the lithium ion batteries of the anode is the almost always graphite, so most be research is being done on the cathode and electrolyte materials. By reducing the size of the materials used in the Nano battery, higher the conductivity can be reached, leading to the increase in the power, in both charge and the discharge.

Nano battery design for sensor power units

The expected applications of the Nano scale sensors will be require these systems to have an independent of the power source, such as the battery. Previous work has been the performed by Teeters in the area of the Nano battery development and characterization. This work has been the concerned with the construction of the individual nm scale battery arrays containing nanometre.

Teeters’ group has been developed the methods to make arrays of the batteries using commercially available nonporous alumina membranes Synkera Technologies, Longmont, CO having hexagonally ordered pores. These pores can be range from several hundred nanometres to the smaller than 10 nanometres in diameter. The thickness of the membranes is the maximum of 60 microns or less. The techniques for the making Nano battery arrays have been developed by the Teeters’ group and will be the summarized below.

Arrays of the Nano batteries are the made by sealing one side of the membrane with the polymer film and the applying a coating of sol gel electrolyte material such as the V2 O5 on the opposite side. Since the Nano pores in the membrane are the sealed on one side, the sol gel can only partially penetrate into the pores. The sol gel is the cured forming the electrodes for this side of the membrane. Excess sol gel that is the above the membrane pores has been the found to be simply slough off the leaving individual Nano scale electrodes for the arrays of the Nano batteries at the surface.

The polymer seal is then removed from the other side of the membrane by use of the solvent opening the Nano pores on this side. A molten poly ethylene oxide polymer or inorganic salt electrolyte is the introduced into the open pores facilitated by the capillary action under the vacuum conditions. This side of the membrane is then placed on the continuous layer of the electrode material. This is illustrated in the Figure.

Summary

The bio Nano battery will be enable distributed the power storage systems, making the more flexibility in the circuit design. Characterization of the Fe ferritin and Co ferritin indicate that they would be the good candidates for the bio Nano battery half-cell units. Reconstituting ferritins with the other metallic core materials having a higher redox potential may be improve the power density of the bio Nano battery.

Two dimensional arrays of the ferritins were successfully fabricated on the silicon substrates using the spin self-assembly deposition method. Improving the electron transport and the using multi layered ferritin arrays and ferritins with the other core materials may be improve the bio-Nano battery performance.


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