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A capacitor is often constructed with two layers of conducting foil separated by a paper-thin layer of insulator. The capacity of such a device is proportional to the area of the foil A and inversely proportional to the insulator thickness t, C∝A/t. A supercapacitor has an atomic scale insulator thickness given by the solvation layer surrounding an ion in an electrolyte, and a large surface area. Supercapacitor on the order of {{http://latex.codecogs.com/gif.latex?\tiny%20\dpi{120}%20\bg_white%2010^{0}-10^{3} }} Farads are now [[https://www.sparkfun.com/products/746|commercially available]] and approach the energy density of batteries while still offering fast charge and discharge rates. A capacitor is often constructed with two layers of conducting foil separated by a paper-thin layer of insulator. The capacity of such a device is proportional to the area of the foil A and inversely proportional to the insulator thickness t, C∝A/t. A supercapacitor has an atomic scale insulator thickness given by the solvation layer surrounding an ion in an electrolyte, and a large surface area. Supercapacitors on the order of 10^0^ - 10^3^ Farads are now [[https://www.sparkfun.com/products/746|commercially available]] and approach the energy density of batteries while still offering fast charge and discharge rates.
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=== Material Safety Data Sheets ===

[[https://dl.dropboxusercontent.com/s/jlb2lp4a8j9ed6f/msds_NaNO3.pdf?token_hash=AAGDr00itM6VIIO58fTmJvg9dXfPPMU9MCdDNeYyvee3PQ&disable_range=1|Sodium Nitrate]]
[[https://dl.dropboxusercontent.com/s/lvmatpsqzzhpqzh/msds_P2O5.pdf?token_hash=AAEEvlmiLbqMVwHMnd9RgIEdSnAUcjztoVQPY5pHef8QsQ&disable_range=1|Phosphorus Pentoxide]]
[[https://dl.dropboxusercontent.com/s/lx2807zy39s0kwk/msds_KMnO4.pdf?token_hash=AAGeQOzIkfuJUVHJxj_xQEdRLh3Tt1a-2H5bmvxrQ-LQ5Q&disable_range=1|Potassium Permanganate]]
[[https://dl.dropboxusercontent.com/s/2m89qe5jti1yq02/msds_H2SO4.pdf?token_hash=AAEMa6XIVAg8n60fH4t3fxZe8loLCagE_p4DmND7wOFgBg&disable_range=1|Sulfuric Acid]]
[[https://dl.dropboxusercontent.com/s/3mi2rcfctc1y0sk/msds_H2O2_3%25.pdf?token_hash=AAFOVWNSiH2XxhBTp7OqdkucaIEe5dqbHpPGd4waFy_K6g&disable_range=1|Hydrogen Peroxide]]
[[https://dl.dropboxusercontent.com/s/uro3qybz6zyh25v/msds_Graphite.pdf?token_hash=AAHPU8pcn7vEmAcjJDCu9vtf_p-3gh0bUFFvIHbtzuMh2w&disable_range=1|Graphite]]
[[https://dl.dropboxusercontent.com/s/acc7o4uc6b3k3pu/msds_GrapheneOxide.pdf?token_hash=AAHrhS7oxXmd5odPwaZ0rg1g_0aSdMsm3zTMeY3jR6Ambw&disable_range=1|Graphene Oxide]]
[[https://dl.dropboxusercontent.com/s/6fynh2dafjp76os/msds_GrapheneOxide_inH2O.pdf?token_hash=AAHZ3eg1jHQhpCK0P6ZeSY_7bASWPalDPbe2sDvNTf_8OA&disable_range=1|Dispersed Graphene Oxide]]

Graphene Micro-Supercapacitors

Project Overview

The electronic devices we use in our everyday life utilize two different types of electrical sources in order to operate: batteries and capacitors. A battery stores a fair amount of energy but is slow to charge and discharge (low power density). A capacitor can charge and discharge very rapidly (high power density) but stores a very small amount of energy. A supercapacitor combines the best of both by storing a large amount of energy while also being able to charge and discharge very rapidly.

A capacitor is often constructed with two layers of conducting foil separated by a paper-thin layer of insulator. The capacity of such a device is proportional to the area of the foil A and inversely proportional to the insulator thickness t, C∝A/t. A supercapacitor has an atomic scale insulator thickness given by the solvation layer surrounding an ion in an electrolyte, and a large surface area. Supercapacitors on the order of 100 - 103 Farads are now commercially available and approach the energy density of batteries while still offering fast charge and discharge rates.

The authors of the Nature paper below, El-Kady and Kaner, have provided a video introduction to graphene based supercapacitors.

Fabrication of Microsupercapacitors

Project Goals

Short Term Goals
  1. Create graphene micro-supercapacitor material using the methods outlined by El-Kady and Kaner.
  2. Conduct a series of tests on how to maximize the amount of charge stored within each graphene micro-supercapacitor.

Long Term Goals
  1. Design an apparatus that can hold many graphene micro-supercapcitors in an efficient and usable way for use in application.
  2. Experiment with powering small mobile devices (ie. a flash light, a watch, a cellphone).

Relevant Publications

  • Scalable fabrication of high-power graphene micro-supercapacitors for flexible and on-chip energy storage

    • Maher F. El-Kady & Richard B. Kaner

      • El-Kady and Kaner demonstrate a scalable fabrication of graphene micro-supercapacitors over large areas by direct laser writing on graphite oxide films. More than 100 micro-supercapacitors can be produced on a single disc in 30 min or less. The devices are built on flexible substrates for flexible electronics and on-chip uses. Remarkably, miniaturizing the devices to the microscale results in enhanced charge-storage capacity and rate capability. These microsupercapacitors demonstrate a power density of ~200 W cm-3, which is among the highest values achieved for any supercapacitor.

    Preparation of Graphitic Oxide

    • William S. Hummers & Richard E. Offema

      • The conventional method for the preparation of graphitic oxide is time consuming and hazardous. Hummers and Offema have developed a rapid, relatively safe method for preparing graphitic oxide from graphite in what is essentially an anhydrous mixture of sulfuric acid, sodium nitrate and potassium permanganate.

    Layer-by-Layer Assembly of Ultrathin Composite Films from Micron-Sized Graphite Oxide Sheets and Polycations

    • Nina I. Kovtyukhova et al.
      • For the synthesis of graphitic oxide, El-Kady and Kaner used a modified Hummers' method developed by Nina I. Kovtyukhova et al.

This article

"High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance," http://dx.doi.org/10.1038/nmat3601, http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat3601.html

got me wondering about an old amazing thing. Palladium is a sponge for hydrogen, a phenomenon once touted as a means to achieve "cold fusion."

"Hydrogen in thin Pd-based layers deposited on reticulated vitreous carbon—A new system for electrochemical capacitors,"M. Łukaszewskia, A. Żurowskia,cA. Czerwińskia, Journal of Power Sources Volume 185, Issue 2, 1 December 2008, Pages 1598–1604, http://dx.doi.org.ezproxy.library.wisc.edu/10.1016/j.jpowsour.2008.08.002

-duncan

Finance

Short term budget

Material Safety Data Sheets

Sodium Nitrate Phosphorus Pentoxide Potassium Permanganate Sulfuric Acid Hydrogen Peroxide Graphite Graphene Oxide Dispersed Graphene Oxide

None: Graphene Micro-Supercapacitors (last edited 2013-10-28 21:42:06 by DuncanCarlsmith)