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Topic: Lithium ion battery  (Read 9129 times)

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Offline Rutherford

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Lithium ion battery
« on: October 14, 2013, 10:42:39 AM »
The problem is attached.
Firstly, what material is used for which electrode? I suppose that it is C anode and LiCoO2 cathode, but is it, why?
In discharged state the mass is 10g. How to calculate the mass in charged state? What causes the charged state?

Offline Rutherford

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Re: Lithium ion battery
« Reply #1 on: October 15, 2013, 02:17:31 PM »
Any reference would be useful, too.

Offline AWK

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Re: Lithium ion battery
« Reply #2 on: October 16, 2013, 11:29:43 AM »
This is quite simple limiting reagent problem
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Offline Rutherford

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Re: Lithium ion battery
« Reply #3 on: October 16, 2013, 11:33:55 AM »
But I got confused. What is the anode and why, and what happens so the battery gets charged?

Offline AWK

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Re: Lithium ion battery
« Reply #4 on: October 16, 2013, 12:13:19 PM »
You have compounds in charged battery on the left side.
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Offline Rutherford

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Re: Lithium ion battery
« Reply #5 on: October 16, 2013, 01:12:13 PM »
Good, so this reaction happens during charging:
LiCoO2+6C :rarrow: CoO2+LiC6
nLiCoO2=0102mol; nC=0.833mol therefore LiCoO2 is the limiting reagent. C is the anode. The mass of the anode is: m=(0.833-6*0.102)*12=2.652g, but this is not correct. Where did I mistake? This is their solution:
10.00 + 0.1022 × 6.94 = 10.709 g, how?

Offline Borek

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Re: Lithium ion battery
« Reply #6 on: October 16, 2013, 01:37:29 PM »
Anode is 10 g of carbon (this doesn't change whether the battery is charged or not) plus all metallic Li.
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Offline Rutherford

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Re: Lithium ion battery
« Reply #7 on: October 16, 2013, 03:29:44 PM »
The 6C that reacted are deposited as C6-, plus the Li+ would give the correct mass, but isn't this the mass of the substances in the anode area, but not the anode? The anode should be carbon only, right?

Offline Borek

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Re: Lithium ion battery
« Reply #8 on: October 16, 2013, 04:00:16 PM »
Lithium gets built into the carbon matrix, you can't say where the carbon ends and lithium starts, it is one solid.
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Offline AWK

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Re: Lithium ion battery
« Reply #9 on: October 17, 2013, 02:51:01 AM »
I think author of this question thinks classically - charged battery contains CoO2 nad LiC6 - and your result is correct.
http://enerchem.blogspot.com/2010/08/lithium-ion-battery-extending-life.html
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Offline Rutherford

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Re: Lithium ion battery
« Reply #10 on: October 17, 2013, 08:19:43 AM »
Lithium gets built into the carbon matrix, you can't say where the carbon ends and lithium starts, it is one solid.
Thank you for the explanation. I understand now.

I think author of this question thinks classically - charged battery contains CoO2 nad LiC6 - and your result is correct.
http://enerchem.blogspot.com/2010/08/lithium-ion-battery-extending-life.html
Thank you for the link.

Offline Big-Daddy

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Re: Lithium ion battery
« Reply #11 on: November 04, 2013, 11:20:06 AM »
Good, so this reaction happens during charging:
LiCoO2+6C :rarrow: CoO2+LiC6

Where did this reaction equation come from? I get that the anode and cathode materials have to be the reactants of the reaction - CoO2 and LiC6 cannot be in solution so evidently they were not present to start with, leaving only the other two - but how do you get that a) this means the cathode is being broken down into CoO2 and b) the Li+ are being transferred to the anode where they are reacting to form LiC6 (this is the tough step - looks like it is going the opposite way in the anode direction)? None of these seems to follow logically for me...

Offline Rutherford

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Re: Lithium ion battery
« Reply #12 on: November 05, 2013, 03:22:25 PM »
If you write the reaction reversely you will get the overall reaction of the electrolysis. You need to put energy for the reaction to happen. When the reaction is over, the battery is charged and the reaction I wrote happens. That's how a secondary cell works: http://en.wikipedia.org/wiki/Electrical_battery#Secondary_batteries

Offline Big-Daddy

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Re: Lithium ion battery
« Reply #13 on: November 07, 2013, 08:42:24 PM »
One step at a time please :p Given that the cathode and anode reactions are given as they are, the reaction which one drives forward by applying energy is CoO2 + LiC6  :rarrow: LiCoO2 + 6C. First, how does this reaction go forward when neither CoO2 nor LiC6 appears to be initially present?

So the cathode is gaining charge because, apparently, LiCoO2 is being formed there, while graphite is formed at the anode (which is losing Li from LiC6 and thus becoming discharged). In light of this, what do those initial conditions mean, and how do they work - after all the electrolysis reaction should be impossible if neither of the reactants are present?

Offline Rutherford

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Re: Lithium ion battery
« Reply #14 on: November 08, 2013, 11:08:07 AM »
No. The reverse action is happening when applying energy. And there are 10g of both reactants.

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