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| =<center>Phage nanowires</center>= | | =<center>Phage nanowires</center>= |
| ==Introduction== | | ==Introduction== |
− | The materials prepared in this lab will be either an anode (Co3O4), or a cathode (FePO4•H2O). Both of these materials have activity as battery electrodes. The redox properties of the material will determine the operating voltage of the electrode, while other properties of the material will improve capacity (how long the battery will last under a given current load) and rate capability (how quickly the battery can be discharged or charged). Capacity and rate capability can be improved by either making materials very small (nanomaterials) or by incorporating conducting metals into the matrix of the material.
| + | Edited from material originally written by the Belcher lab. Special thanks to Mark Allen, and Lieutenant Colonel F. John Burpo. <br> |
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− | This lab will take place over four weeks, 1st session will be material synthesis, 2nd session will be analyzing material by TEM, 3rd session will be forming dried material into electrodes, and 4th session will be assembling a coin type battery. In this lab, each group will make both an anode battery cell and a cathode battery cell. Since there are four groups, it is possible to make each battery under four conditions. One group can make Co3O4 and FePO4•H2O on phage, another group will prepare these same materials without phage, a third and fourth group will incorporate phage with silver and gold nanowires (respectively) at a ratio of 2/100th of the amount of active material. The activities of these four conditions can be compared by all four groups.
| + | [[Image:CoinBattery.jpg|thumb|Coin-type battery]]The materials prepared in this lab have activity as battery electrodes. The redox properties of the material will determine the operating voltage of the electrode, while other properties of the material will improve capacity (how long the battery will last under a given current load) and rate capability (how quickly the battery can be discharged or charged). Capacity and rate capability can be improved by either making materials very small (nanomaterials) or by incorporating conducting metals into the matrix of the material. |
− | In order to determine the capacity of each battery we will be testing each battery on a Galvanostat. This is a machine that can apply either positive or negative current in order to either charge or discharge a battery with a specific amount of current. As an example, look at your cell phone battery, if you have a typical LiCoO2 lithium ion battery you will notice that it has a voltage (3.7 V) and a capacity (mine is 1100 mAh). We know that LiCoO2 has a theoretical capacity of 130 mAh/g, so in my battery I must have about 8.5 g of active material in my cell phone battery. The way that the capacity and voltage was determined was identical to what you will be doing in this lab, i.e. they hooked up my battery to a Galvanostat and applied a constant current (1100 mA) in order to charge the battery in one hour, and the applied a negative current of 1100 mA to discharge my battery in one hour. Figure 2 is an example of the curve that you will be generating. This is a charge/discharge curve for FePO4.2H2O, the positive slope curve is the charge curve and the negative slope is the discharge curve. The plateau centered around 3 V corresponds to the operating voltage of the battery. In answering the questions in this lab, you will be able to compare the capacity of each of your batteries, you can compare the operating voltage and if there is time you can look at cycling of the battery if you are able to come back and look at how well your battery performs after several cycles.
| + | Assembly and testing of the phage-based battery will take place over several sessions. Today's lab will focus on material synthesis. The next lab will be analyzing material by TEM. In the final sessions of the module, dried materials will be formed into electrodes, and finally, these materials will be assembled into a coin type battery and tested. Groups will vary the amount of silver in the gold phage nanowires to see how these variations affect the charge/discharge cycle. |
− | | + | Today in lab you will calculate the concentration of phage stock you've prepared and then react it with gold and silver. You will have time while these reactions are going on to work on the research proposal idea you've got started with your lab partner. |
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| ==Protocols== | | ==Protocols== |
| ===Part 1: Dilute the 8#9 phage stock=== | | ===Part 1: Dilute the 8#9 phage stock=== |
− | Count the number of plaques on your phage titering plates from last time. Calculate the concentration of phage in your undiluted purified phage sample. Be sure to take into account each dilution when you try this calculation. Express the concentration as PFU/ul and determine the volume of phage needed to make 10 ml of 3.5x10^7 PFU/µl. | + | Count the number of plaques on your phage titering plates from last time. Calculate the concentration of phage in your undiluted purified phage sample. Be sure to take into account each dilution when you try this calculation. Express the concentration as PFU/ul and determine the volume of phage needed to make 10 ml of 3.5x10^7 PFU/ |