The Periodic Table - 2014-12-02

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5:42 AM

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Q: Houston, we have a "Problem" in question titles

So we are all familiar with the drill, given through the following: I question the use of "question" in question titles Help make help questions have more helpful titles There are currently 34 uses of "problem" in titles which could benefit from some more descriptive headings: http://chemis...

discussion editing titles

10 hours later…

4:06 PM

@LordStryker hola.

\o

I'm the crazy grad student working on the battery project =)

Yes I remember :)

How goes it?

so I got to talk with the chemistry department head, and got some good direction. Using the Materials Science Genome Project

brilliantly, it cuts out a huge portion of the research that would need to be done, that takes years of cutting edge technology. so currently I'm restricting my search to materials published by that project

materialsproject.org

Sounds wonderful!

4:09 PM

anyways, I got a system up and running, that is basically just copying their database locally,

it looks like an amazing project on its own

so here is the question I was trying to ask,

well, let me backup,

If a battery is a set of two+ reactions

those reactions will have some 'clean' formula, correct ? like the following links

Pb(s) + PbO
2(s) + 2H
2SO
4(aq) → 2PbSO
4(s) + 2H
2O(l)

so, instead of trying to simulate a reaction

I wanted to eliminate reactions that should not be simulated

before simulating any reaction

at any temp / pressure / with other compounds

etc.

Hmm, I suppose I'm confused by what you're asking.

4:25 PM

let me try again,

before using high performance computers to simulate a reaction, you want to know the reaction is legitimate and valid

so, the first step is to eliminate invalid reactions

the assumption is this

for a given battery, there will be a 'simple' formula similar to the equations found here:

Lead–acid battery

The lead–acid battery was invented in 1859 by French physicist Gaston Planté and is the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, its ability to supply high surge currents means that the cells have a relatively large power-to-weight ratio. These features, along with their low cost, makes it attractive for use in motor vehicles to provide the high current required by automobile starter motors. As they are inexpensive compared to newer technologies, lead-acid batteries are widely used even when surge current is not important...

Lithium-ion battery

A lithium-ion battery (sometimes Li-ion battery or LIB) is a member of a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte which allows for ionic movement, and the two electrodes are the consistent components of a lithium-ion cell. Lithium-ion batteries are common in consumer electronics. They are one of the most popular...

basically, look for the equation of the reaction

Yes. Okay I understand that part.

mostly, I want to validate my assumptions ,before continuing

because the next step will probably take a year or two to complete, if I'm lucky

Yes, that makes sense because blindly charging into this would not be efficient.

the awesome part is this

there are lots of 'magic' numbers, with each compound, so you can get a very rough estimate of the energy of a reaction

so, if there is a valid reaction, you basically get the energy of the reaction without having to go to full simulation

which is highly advantageous in terms of computation cycles used

4:41 PM

as long as you know reactants and products you can get the energy of reaction yes

But if you're mapping out a reaction pathway you have to show that reactants are indeed connected to products

^^ exactly, this is the 'network' that I really want to build

so that you can follow a series of pathways 'down' and 'up' in energy levels

because if you can map these networks out

you can find multiple pathways

What do you mean by 'energy levels'?

potential energy stored / expended, I know my terminology is wrong, so I need to learn what that really is

like

CH4 is high potential energy

So are you simply interested in looking at electronic energy differences (i.e. energy of products - energy of reactants) or will you be looking at free energies and/or other thermodynamic quantities?

I would like to consider them, but I don't know how to at this point

because the difference between a lot of free electrons and free photons is the difference between a battery and bomb right?

right now, I was simply planning on looking at electronic energy differences, which may not be good enough

4:47 PM

Its definitely a start and may be very insightful (aka publishable)

Explore the literature and see what others have done.

aye, so here is a perfect application

mdpi.com/2073-4344/3/2/563/pdf

I've published a paper exploring a reaction mechanism that only dealt with electronic energies

you want the reactions as follows

dang, they don't have the actual reaction you want

But with batteries I imagine that thermodynamic properties will be very important

such as behavior with changing temperature

incedibly, but I figure before even looking at those

incredibly*

look for legitimate valid cycles in the network

so what that paper talks about is catalysts for methane production, and they are looking for materials to solve the coking problem (buildup of carbon ash in the chamber)

so they know where they are coming from, where they are going to, and the amount of theoretical energy you will need at a minimum to get there

but they need a different route from A to B, that doesn't have carbon ash as one of the possible reactants

5:00 PM

Sounds challenging

someone got published because of it =)

this should be an effective way to 'figure out' some of those potential pathways, to get from A to B,

there are methods which people are trying to 'push' as being efficient

ooo

but perhaps they haven't been tested enough or recognized widely in the literature

now I'm interested,

explain ?

5:02 PM

i vaguely remember someone mentioning to me some sort of 'elastic-band' method or procedure to mapping out reaction pathways

you could try searching for something like that

will do,

other searches to add to bibliography ?

*nudged elastic band (NEB)

start with NEB and see who they cite

I need to convince my adviser, and chemistry department head, that its worth perusing

pursuing *

will do

i'm certain you will find them referencing papers that use different procedures (i.e. "our method is better than this 'other one'")

of course, because the only right way is my way!

5:04 PM

Well, the method may be better in certain cases

but may not be universally well-behaved

gotcha

i seriously want to find the way to use NaCl and Fe2O3 as a battery =) that would make production so easy =)

alright, thanks again for your time, I'll be back again at some point I'm sure =)

<o

have a great one

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