Micro-CT of a Battery
Micro-CT is a powerful tool that allows researchers to look inside objects non-destructively so that the sample can be used for further tests. In this case, a micro-CT of a battery was performed using our Bruker SkyScan 1275 micro-CT system. The D-Cell battery was scanned and could then be depleted later, or in steps, to see the affects discharging the battery has on the internal structure of the battery. This ability to perform further tests on samples is another advantage of using a micro-CT system to investigate internal structures.
How Batteries Work
Alkaline batteries—portable, self-contained, chemical power packs that give us a steady supply of electrical energy wherever we need it—power our mobile world, from disposable cameras to portable CD players and incandescent flashlights. The makeup of batteries has changed slightly over the years, but the concept of dry cell batteries dates back to 1868, when French scientist Georges Leclanché invented a battery that later led to the first dry cell battery.
Batteries work by slowly releasing electric current due to a potential difference generated by chemical reactions. The key components of a battery are a positive electrode or cathode, a negative electrode or anode, and a separator to keep the electrodes apart. The electrodes are always made from two dissimilar materials that both conduct electricity. One of the materials “likes” to give up electrons while the other “likes” to receive them. In the alkaline battery we scanned, the zinc and hydroxide anode react to make zinc oxide, water, and give up electrons. These electrons have an attraction to the manganese dioxide cathode of the battery. Thus, they flow outside the battery to power a device, and then back into the battery, completing the circuit. These returning electrons, along with the reaction of manganese dioxide and water, form manganese (III) oxide. When all the zinc is used up to create zinc oxide, the battery is spent1.
To take a look at what is inside a basic alkaline battery, we used the newest SkyScan 1275 for fast, non-destructive micro-CT imaging.
Battery Anatomy
The alkaline battery we scanned has a steel casing that houses the components required for the electrochemical reactions that produce electrical energy. Just inside the steel casing is manganese dioxide power, which acts as the cathode (where electrons return back to the battery). Next is a paper separator that is soaked with potassium hydroxide. This acts as an electrolyte, which is a stable solution to prevent the mixture of the manganese dioxide and zinc powder. On the other side of the paper separator is the zinc powder with potassium hydroxide, which acts as the anode (where electrons leave the battery). The collector pin, which is usually brass, carries the electrons outside the battery to power the electric device1, 2.
The SkyScan 1275 Micro-CT Scan of a D-Cell Alkaline Battery
Using the fast SkyScan 1275 Micro-CT scanner we were able to non-destructively visualize the inner workings of an entire battery at a fraction of the time required by past scanners, which would have taken about eight hours to scan a similar D-cell battery at the same resolution. With the SkyScan 1275, the scan time is reduced to about two hours while retaining exceptional image quality. The quality of the micro-CT scan of the battery allows us to see the full anatomy of this D-Cell. An automatic sample changer can be added to increase the sample throughput, even into weekends.
Hopefully, you have learned more about the workings of batteries and we hope you will think of us the next you use a battery-powered device. If you have a cool Micro-CT application, we would be glad to highlight it as the next image of the month. If you have any questions about micro-CT or the instruments we provide, we would be happy to discuss them with you.
Feel free to contact us by calling 610-366-7103 or by e-mailing brandon@microphotonics.com
Micro-CT SCAN SPECIFICATIONS
System
Voltage
100kV
Current
100µA
Pixel Size
25um
Rotation Step:
0.2
Total Scan Time
02:19:24 (HH:MM:SS)
Software
NRecon, DataViewer, CTVox
Location
Micro Photonics Imaging Laboratory, Allentown, PA
Works Cited
- http://www.electrical4u.com/alkaline-batteries/
NOTE: Because we were scanning a battery with metal and other high-density material, using the system’s copper filter served to block out lower energy X-rays, limit X-ray scattering, and cut down excess noise to provide the best contrast for this scan. Alternatively, we could have added a brass filter to handle the high-density materials. (See our Tip of the Month for November 2016 for the steps to follow to add an additional filter to the SkyScan 1275.)