Bought K2S for my NiFe batteries (experimental)

Hi,

- Have some NiFe batteries. Apart from water top-ups nothing to mention. (2,5 years old now)

Was investigating the elektrolyte additives.
Like this research paper here:

https://www.researchgate.net/publication/281270076_The_Effect_of_Electrolyte_Additives_on_the_Performance_of_Iron_Based_Anodes_for_NiFe_Cells/link/55dd9ebb08ae83e420ee9bf3/download

I actually wanted to try the Pottasiumsulfide!
Seems nobody have tried this on (any?) forum, so I want to take the risk/experiment with it!
So I bought some K2S for my batteries. (it's not that expensive)

Will try the 0,4 value, which seems to give the best results. (See figure 8 in the paper)

The hydrogen generation is really the only downside I can find about the Nickel-Iron chemistry (at least, the only downside,
that actually matters in day to day usage: watering) (forget about size, self discharge doesn't really matter at all)

I will try ONE battery at first, just as a precaution.


Greetings,
Steven.

Steven,

I for one am extremely curious as to how well this battery material works out.

Today, all the hype is based on Lithium-Ion batteries which are great for lightweight and mobile applications.  But for stationary purposes, who cares about weight?  You might be on to something and I eagerly await your findings.

Eric

Here is the check sheet I made.

Their 0,4 value comes out as 26,11 gr in one liter of elektrolyte.
(If I have calculated that right)
My manual specifies 20g lioh, that's about right.

Package with the K²S arrived!

I measured the desired quantity (in the check sheet above)

Then I pulled back some elektrolyte and dissolved the K²S in it. I does dissolve a bit like the LiOh powder.
(needs a bit of work). Then I poured in into the first battery.

The good news is: battery still works fine.
I have just ran one charge/discharge cycle.

I am not totally sure how we compare the modified elektrolyte to the other 19 batteries.
We can measure discharge voltage and charge voltage. Measuring hydrogen generation is another matter. (finger on vent hole?
balloon across cap?) Water consumption would also be an indicator.

I think I'l first let it run for a few charge/discharge cycles.

That's it for now.

Greetings,
Steven

5 batteries done.

I might have added too little?
Quote from the paper:

it is usually encounter with most NiFe electrolyte systems at a concentration close to 0.1 M

0.1M = 20mg ? (what most manufacturers recommend, including mine: Henan Hengming)

Will do half of the battery bank.
Then wait & see. and then double the concentration if too little effect.

The first battery (done saterday 29/5)  continues to work fine.
I would say it's voltage is slightly higher then the rest. But it's too soon to draw a conclusion I think.
There are always some small variations.

Conclusion so far: no damage, no problems.

Steven,

Very impressive!  Have you tried any sort of battery stress test to see what practical run times/amp hours/watt hours/etc. you can get out?

Eric

Eric Hanson wrote:Steven,

Very impressive!  Have you tried any sort of battery stress test to see what practical run times/amp hours/watt hours/etc. you can get out?

Eric

10 of 20 batteries done.
Will think about measuring/battery stress test.
No sun @ moment, so will have to wait.

I would like to measure the hydrogen generation too.
I can put a ballon over the vent cap top for a few minutes.  Then compare with another battery that had no k2s added.

Not sure what sort of screw thread the Chinese used for these batteries.

Small update.

Load test at night.
The 10 batteries with K²S are 0,03V higher then the other 10.
That's not much, but we'll see how it evolves. Ill effects: none

So it seems it takes some time (charge/discharge) to get the elektrolyte to cycle in and out of the plates.
We will measure water consumption later.

I am tempted to double the concentration of the additive on 5 batteries.
Then we have 5 @ 180gr, 5 @ 90gr and 10 with no additive(reference group).

But maybe I should wailt longer.
What do you think?

Greetings,
Steven.

Update 6/7/2021

I have checked the elektrolyte levels of all batteries.
The 10 batteries with K²S added have consumed less water, compared to the 10 others.

I am going to wait longer to see if the difference increases.
(water levels have dropped 1cm on the non-threated batteries, and just 0,5cm on the batteries with K²S)
But that's encouraging!

Voltage checks don't really give a good indication I found. The're still pretty good
at self balancing

Will see what it is next month.
I do am temped to double the concentration on 5 of them.

Like this
5 with 180gr / ~3l elektrolyte in each cell
5 with 90 gr /~3l elektrolyte in each cell
10 with none (check group)

What do you think?

Greetings,
Steven.

Update 11/7:

Increased the K²S in 5 cells to 180gr / cell.
This will be my high limit for this experiment.

So for now:

5 with 180gr K²S / ~3l elektrolyte in each cell
5 with 90 gr K²S /~3l elektrolyte in each cell
10 with none (check group)

So far all cells continue to work fine.