# LiMn2O4



## DIYguy (Sep 18, 2008)

beware of thermal runaway with this battery. I think it actually explodes in overcharge situations.... particularly in larger battery applications.


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## Buckster (Nov 4, 2009)

DIYguy said:


> beware of thermal runaway with this battery. I think it actually explodes in overcharge situations.... particularly in larger battery applications.


Really? Am I right in thinking that manganese dioxide is a liquid substrate that becomes unstable above 50C?


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## DIYguy (Sep 18, 2008)

there u go.... no wonder its cheaper.. Got good temp compensation charging? lol


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## _GonZo_ (Mar 23, 2009)

Actually this cells are quite safe even safer than the ones with LiCoO2 catode, but major issues are short life and low power.


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## DIYguy (Sep 18, 2008)

http://resources.metapress.com/pdf-preview.axd?code=v375w73vlm117588&size=largesthttp://resources.metapress.com/pdf-preview.axd?code=j16882l8h463q5m&size=largest


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## MN Driver (Sep 29, 2009)

Lithium Manganese batteries don't have a very long cycle life, at least from the manufacturers spec sheets I've run into they don't seem to, things could have changed and I haven't seen every cell specsheet out there. There is one very good advantage to Lithium Manganese is that their internal resistence doesn't change as they age, just the capacity but they lose their capacity in a very consistent way in a pack in comparison to Lithium Cobalt. Lithium Iron Phosphate, just like the rest of the Lithium chemistries lose their ability to dump amperage out of the pack and maintain the same voltage but this isn't an issue with the LiMn chemistry, instead the capacity is just reduced with cycling. I believe they have more watt-hours per volume than LiFePO4 too, they also have a higher nominal voltage too. Doctorbass on the endless-sphere forum is using a Lithium Manganese pack with his ebike and 432 Konion cells cells pulled from used Makita power tool packs and he doesn't use a BMS because he matches the cells so they all have the same capacity and he hasn't spoken of any problems and that is alot of cells too. He has 202km range with it. Not many electric vehicles are setup to go 125 miles like his. They don't seem to provide a very high power capacity(amp draw) capability although with the proper capacity that shouldn't be an issue. The cells may be a bit more expensive too since there isn't a huge amount of competition. Getting cheap cells probably means dealing with the 1.5Ah Konion cells from Makita packs with isn't going to make life easy for anything but an Ebike, even then it's quite a bit of work.

I personally think the 'all Lithium except LiFePO4 is going to cause your car to explode' argument doesn't apply so much if the pack is managed properly with high and low voltage hard cutoffs with current and thermal fusing(which I think should be on all Lithium chemistries including LiFePO4), Lithium Cobalt has a higher cost though so I personally won't be using it because of that but if I found large format cells with good specs at a good price of Lithium Manganese or Lithium Cobalt with a comparable cost per kilowatt factored in with cycle life as a cost per life measurement, I'd gladly buy and use them, it would make my pack smaller and lighter and I'd need less cells to monitor for the same voltage.

Edit: Lucky Goldstar Chem uses lithium manganese as its cathode and they are a very high volume battery producer too, these are the cells going into the Chevy Volt which will have a 10 year 150k mile warranty on the battery, so things have advanced for these cells and we just don't know it yet. ...time will tell.


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## _GonZo_ (Mar 23, 2009)

In order to add some more info about this chemistry:

Life capacity density is around 100Wh/Kg
Nominal voltage for LiFe: 3,3V
Li-Ion is around 150Wh/kg or more (there is a tendency to increase density at the same time that power decrease and viceversa)
Li-Ion nominal voltage: 3,7V

Usually on Li Manganese anode is grafite but hard carbon is another posibility, that increases battery life but rises price...

As MN Driver says if well managed there should not be risck of fire or explosion wiht them, actually are vastly used on phone, laptops, etc.
And if well managed number of cycles can be encreased.


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## roflwaffle (Sep 9, 2008)

In terms of deep cycling they aren't as good as LFPs (~2000 cycles to 80% capacity versus ~3000-6000 cycles w/ LFP), but they offer greater power to weight than LFPs of comparable prices (Kind of a deal breaker for a PHEV, not so much for an EV) and are cheaper than A123's offerings. My post here has a link to a pdf w/ some specs. W/ shallow cycling they start to approach cheap LFPs in terms of the amount of energy they can store, they just don't do as well w/ deeper cycling.


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