Supercapacitors how do they really work - Page 1
Forum section: electronics / projects

author: robint
author_rank: Regular Contributor
timestamp: March 20, 2024, 10:48:22 am
content: Hi GuysI need help here, I have been searching for months now to try and find a plausible explanation of how a Supercapacitor really works. Please dont offer comments of an elementary nature or refer to classic caps. This is a serious question for technical/scientific informed views. No idle speculatorsI am a real engineer with quality training and background so I can spot all the specious rubbish published about the mysteries of Supercapacitors - its frustrating to have my time wasted with yada yada. Please help here if you can with links.Until recently I hade never come in contact with high values > 500uF electrolytics. So the concept of 5000F is fantastic to me 10^7 x bigger.I am aware of the properties of Activated Carbon (AC) and it has a surface area far greater than normal charcoal (ca 1500m2/g vs 5m2/g)A lot of terminology gets mixed up by ignorant writers as a Capacitor is not like a battery which is electrochemical in operation. I a capacitor we have charge collection plates, a thin coating of AC, a separator allowing ionic transport and an electrolyte for the movement of ions to the charge collection plates. AFAIK electrodes dont come into it?Now we should all be familiar with C = e*eo*A/d eo = fundamental permittivity 8.84*10^12So we take 2 plates (collectors) in a tank, fill with electrolyte, coat collectors with AC (btw AC doesnt stick to metals), put a separator (which can be a simple sheet of paper) between the two to allow ion transfer but not electrical current - so it insulates between the two collectors (but SCs have a inherent high leakage current BTW). AFAIK because the AC has a high surface area it can collect a large amount of ions due to applied electric field (is this right?). The movement and arrangement of such a large amount of ions close together is what creates a large capacitance and storage of energy.A disadvantage is that AC is a poor electrical conductor and so additional powders (like graphite which doesnt have large area ) have to be added to make an SC work.There are several experimenters who claim to have made SCs on YT only one I found an amateur dabbler worth mentioning here and he claims to make a 500F capacitor in a fliptop peppermint packet.Start hereTest results (sort off)Sorry it comes across as Mickey Mouse but at least the guy is trying real methods, not armchair speculation so be forgivingThats as far as I got, discarding 99.9% of the rubbish on GGLe

author: tszaboo
author_rank: Super Contributor
timestamp: March 20, 2024, 11:12:11 am
content: Look it's a homemade supercapacitor. Cuts the video. Here is the test of the supercapacitor.So unlike regular capacitors, that rely on electrostatic-ism (is that a word?) to store energy, supercapacitors store it in a chemical way. Just like batteries. But it's a less energy dense, and more reversible chemical process.

author: robint
author_rank: Regular Contributor
timestamp: March 21, 2024, 08:28:13 am
content: How does this "electrochemical" way work, thats what I want to find out. I cant find any scientific explanation just people and uber hype stringing buzz words togetherScience, engineering not smoke and mirrors please

author: tszaboo
author_rank: Super Contributor
timestamp: March 21, 2024, 08:38:40 am
content: Quote from: robint on March 21, 2024, 08:28:13 amThere is a quite detailed wiki page on this:https://en.wikipedia.org/wiki/Double_layer_(surface_science)

author: Marco
author_rank: Super Contributor
timestamp: March 21, 2024, 07:45:33 pm
content: Alsohttps://en.wikipedia.org/wiki/PseudocapacitorThough it's a bit handwavey still.

author: MarkT
author_rank: Frequent Contributor
timestamp: March 23, 2024, 10:29:56 am
content: And yet another good Wikipedia article:https://en.wikipedia.org/wiki/Supercapacitor