# Are there any alternatives for batteries?

#### DocWonder

OK, so battery companies have already produced amazing results in metamaterials and synthetics especially with graphene doping and lithium ion tech, however many are too expensive for mass production. If you are looking to have a major source of reliable energy with minimal depletion and highly condensed it is already available but not cheap... Nuclear

#### DocWonder

Oh and on a separate note, to solve the problem you are working on, first you must set parameters, like a finite amount of time and an amperage. If you have a low draw of current solar or kinetic generators could direct drive the motor while in use the charge the battery while not in use.

Mentor

#### russ_watters

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Im sorry, but...
C'mon, you're really in need of tough love and we can be extraordinarily helpful if you help us help you. Nowhere in there did you address the problem I highlighted. So do you want false encouragement or do you want real help?

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#### CWatters

Homework Helper
Gold Member
As I understand it one of the big challenges with new battery tech is the fragility or the electrodes. To improve capacity they typically need to maximise surface area, perhaps by making them porous, but expansion and contraction during charge cycles cause damage to fine structures. So when you read about any new battery tech look to see if they have also solved the problems of fast charging and life/number of charge cycles.

C'mon, you're really in need of tough love and we can be extraordinarily helpful if you help us help you. Nowhere in there did you address the problem I highlighted. So do you want false encouragement or do you want real help?
I am accepting criticism, and I am letting a lot of people help on this discussion. If you don't want to participate on this discussion and go to another one, that is up to you.

#### russ_watters

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I am accepting criticism, and I am letting a lot of people help on this discussion. If you don't want to participate on this discussion and go to another one, that is up to you.
I was helping/participating: I did ask you a specific question that would be a big help, but you haven't answered it.

#### CWatters

Homework Helper
Gold Member
I'm with Russ. The question is badly specified. Many wrist watches have "motors" that run for a long time.

#### DocWonder

Following the idea of large surface area does anyone know if they have tried graphene aerogel? Or zeolite? It seems to me that the conductance and porosity of graphene aerogel would be a ringer for this.

#### CWatters

Homework Helper
Gold Member
I believe they have been looking at graphene for some years. If I understand correctly the energy density isn't high enough unless the graphene is compressed and there are problems with just compressing it? I might be wrong/out of date.

#### DocWonder

I am not sure but I have seen where they have doped graphene with other atoms like nitrogen or lithium to improve the power storage. As far as compressing graphene (anyone feel free to correct me on this) but you should not be able to compress it at all theoretically, because it is only one atom thick in one direction and in the other direction (of the tube or sheet surface) it can only configure in the natural hexagonal format, which is due to it's electron configuration. This is now bridging into a materials engineering topic, which brings me back to saying nuclear is the way to go! No I am not talking about a nuclear reactor plant or an industrial sized RTG system. A small scale thermopyle encompassing a decent amount of Americium (radioactive material commonly found in household smoke detectors) should be able to supply at least 5watts for 10 years or so. (I am in no way condoning the unauthorized or uneducation handling of radioactive material).

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#### CWatters

Homework Helper
Gold Member
I didn't mean compress it at the atomic level.

#### That Neuron

Lately, I've done a lot of research on this and m currently building a portable methanol micro reactor targeting portable electronics.

If you're willing to use a hydrocarbon fuel (2-3.something Wh per ml depending on the efficiency) then Direct Methanol/Ethanol or Direct Borohydride Fuel Cells are the way to go.

The reason that they haven't hit the "big-time" yet is because there are currently problems with their power density (how much energy they can release in the form of electricity per time). When you're trying to fit one in a small electronic device this SUCKS, but if you're not constrained by weight or volume, I recommend it.

Also, in response to the other comments on the lithium batteries, I see the most promising change being the adoption and use of silicon electrodes, with them you can basically make the silicon bind to many more li ions than graphite, and thus store more energy. But there are issues with the Li Metal build up on the actual silicon. Some people are using graphene to cage silicon electrode nanoparticles and are having some success, but I'm not sure how far down the track this is.

I have no idea about radioactive batteries, but I assume they'd work like a super efficient geiger counter??

I'd recommend the DMFC, but it's up to you for your specific application.

#### Jeff Rosenbury

Here is the Wikipedia page on energy density. Notice that hydrocarbon solutions are about the best chemical solution for storing energy. These take advantage of "free" oxygen from air. Thus fuel cells are probably the future of consumer electronics (remembering graphene is a hydrocarbon of sorts). They are currently hobbled with technical problems. Until then we have diesel generators.

Beyond that, nuclear cells are a few million times as efficient, but have some serious drawbacks. Still, tritium (3H) gas is relatively safe (relatively, not completely) and has a nice 14 year half-life. A 0.8V, 20 year battery seems to cost about $1,000. At 50 nA, it won't run a large motor (or a small one really). Another potential source is 180Tantalum (metastable Tantalum). Tantalum should decay in about 8 hours, but it doesn't because its high nuclear spin keeps it in a metastable state. It has energy density between fission and chemical processes so might be safe if anyone could figure out how to destablize it easily. (About 1% of Tantalum is 180Tantalum). #### zawy Metal-air batteries (lithium is one type) can do pretty good, not quite as good as reacting oils with oxygen. The metals release a lot of energy when combined with oxygen, sort of trying to return to their original "ore" state. I think aluminum and zinc are the best candidates. Energy storage technology has had an amazing lack of improvement on a cost/Joule basis. The first self-start cars used lead acid and on a Joule per constant dollar basis a lead acid battery cost the same in the 1930's from the Sears mail order catalog as it does today from Walmart. All the technological advances in mining, world trade, and Walmart efficient distribution were not able to offset the increased cost of energy needed to mine, fabricate, and transport and pollution control regulations. Alkaline AA batteries appear to cost the same today on a constant dollar basis as they did in the 1980s, if not more, and we still normally use them instead of lithium or NiMH. Supercapacitors can't compete with batteries. There were several companies 10 years ago jumping onto that bandwagon to get funding by making unproven and unphysical claims. EEStor was the one with the most success, sucking$40 M out of equity markets, even from KPCB investors. They had the biggest success because they were the most successful fraud. The fundamental problem with capacitors is that the internal chemical bonds do not change except by being stretched (unless it is a pseudo-capacitor like electrolytics or a graphene-type). A high dielectric constant is the result of the dipoles affecting each other: you apply a voltage and they begin to separate, but by their separation the 2 neighboring dipoles above and below have their opposite attracting charges get closer to the charges of the dipole in the middle, helping pull each other apart. So there is a feedback between the dipoles that is not storing a lot of energy. You can't raise the voltage much because the bonds break. The best (energy storage) capacitors will have a low dielectric constant, nearly as low as air (k=1).

Batteries on the other hand have electrons that cross the plates and go inside the "dielectric", changing the physical bonds. This is why they can't be cycled "forever" like a true capacitor, and why electrolytics are half battery and don't last forever. Graphene type pseudo-capacitors (half battery by my definition of battery) can only do a little bit better on an energy/weight basis than lead-acid and compressed air. The graphene type is a mixture of polarizing the material and letting electrons get inside the "dieletric" to change the bonds right there at the surface (not really entering too far, but not following the ideal capacitor equation exactly either).

#### anorlunda

Mentor
Gold Member
if you want a better battery, there are multiple ways to define better.

kWh/kg
kW/kg
kWh/l
kW/l
kWh/$kW/$
Charge acceptance rate and efficiency
Operating temperature
Voltage versus charge
Short circuit withstand
Safety and toxicity
Recycleability
Reliability
...blah blah

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