LiFePO4 vs Lithium-Ion Batteries 2024

A lot of people are confused about the difference between lithium-ion vs LiFePO4 batteries – not least because LiFePO4 can also be called lithium iron, aka lithium iron phosphate!

Despite both being lithium-based, there are a number of very meaningful differences between these two battery chemistries, from their varying lifespans (number of charge and discharge cycles) through to their cost, weight, size, and safety.

After living full-time on a boat for over 10 years now, I’ve done some serious research into the best battery set-up to help us live an off-grid lifestyle that still keeps up with our remote work needs. We’ve tried out numerous different batteries, some with more success than others!

We’ve now got the best battery set-up going, with power to last for days (or more importantly for Emily – run the washing machine!) Now we’re here to clear up the differences between LiFePO4 and lithium-ion and help you choose the best one for your needs.

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LiFePO4 vs. Lithium-Ion Batteries: How Do They Compare?

⚡ We use BattleBorn LiFePO4 lithium-ion batteries and love them. They are super easy to install and really have changed our lives onboard.
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Despite their similar names, these two terms refer to batteries with very different properties. First, let’s quickly clear up the names and what they mean.

Lithium-ion is actually a catch-all name for lots of different kinds of batteries – it literally just means “this battery is made of lithium and other ions”, i.e., it’s a compound of lithium and other elements like magnesium, cobalt, or oxygen.

The most common kinds of lithium-ion batteries are LMO (lithium manganese oxide) and LiCoO2 (lithium cobalt oxide).

Bear with us for a second, because this is going to sound confusing at first – LiFePO4 is technically just another type of Lithium-Ion battery. It’s made of Lithium plus other elements, just like LMO or LiCO2 – LiFePO4 is Lithium (Li), Iron (Fe), Phosphorous (P) and Oxygen (O).

But LiFePO4 has such dramatically different properties to other members of the lithium-ion family that we never talk about LiFePO4 as “lithium-ion”, and if you ever see a battery advertised as “lithium-ion” you can be 99.999% certain it is NOT LiFePO4.

That applies to this article too – from this point on, we will never include LiFePO4 in the category “lithium-ion” when talking about their advantages and disadvantages.

What Are The Advantages Of LiFePO4 vs. Lithium-ion?

Let’s delve into some of the main advantages of LiFePO4 batteries.

LiFePO4 is much safer than Li-ion

If you’ve seen stories on the news of lithium batteries spontaneously exploding or setting on fire, zero percent of those were LiFePO4.

Due to chemical properties that we will explore in depth later in the article, LiFePO4 only enters “thermal runaway” – bursts into flames – when the battery reaches 500-540°F / 260-280°C.

If the temperature in your boat or van has reached 540°F you have other problems, like being dead.

It’s also nearly impossible to cause a fire by overcharging, overvolting, piercing, or otherwise abusing a LiFePO4 battery.

Here’s a great video where the Czech fire service attempts to start a LiFePO4 fire by hitting one with an axe, shorting it out, running ridiculous amounts of current through it, and eventually attacking it with a flamethrower (spoiler alert, no fire).

Li-ion, on the other hand, can enter thermal runaway if the cell is pierced or damaged, or reaches ~260°F / 130°C. Li-ion batteries heat up a lot when overcharged, and those temperatures are well within the realms of possibility.

This is how >95% of the lithium fires you see on the news start – Li-ion cells charged with faulty chargers, or the wrong charger (e.g. too high a voltage), or damaged cells.

Why do we still use Li-ion in phones, laptops, scooters, and hoverboards if it can occasionally burst into flames? We’ll see in a moment.

LiFePO4 has a dramatically longer lifespan than Li-ion

We usually talk about battery lifespans in terms of “cycles”, with one cycle referring to the battery being discharged to a certain level and then charged up again. Li-ion batteries are usually good for about 500 cycles.

That means if you’re using it as a “house” battery in an off-grid home, boat, or van, and you’re consuming most of the capacity every single day, a Li-ion battery will have seriously degraded capacity after 500 days, or ~16 months.

LiFePO4 batteries are good for anywhere between 2,000 and 10,000 cycles depending on how deeply you discharge them (5.5 to 27 years). This makes them dramatically more suitable for off-grid applications like cruising sailboats, vans, or solar-powered homes.

LiFePO4 batteries are much cheaper than Li-ion

Li-ion and LiFePO4 batteries usually cost about the same up-front.

But when you consider that LiFePO4 lasts between four and 20 times longer than Li-ion, it’s clear that LiFePO4 represents dramatically better value – unless you desperately need the few advantages that Li-ion can offer.

LiFePO4 is better for the environment than Li-ion

The Li-ion chemistry normally used in our phone and laptop batteries is LCO (LiCoO2). The “C” in LCO is cobalt, which is highly toxic and highly carcinogenic (cancer-causing), and the way it’s mined often causes catastrophic damage to the environment.

There are also a lot of problems with exploitation and modern-day slavery in cobalt mines. Let’s be clear, manufacturing any kind of lithium battery has a significant environmental footprint, but removing cobalt from the mix reduces the impact quite dramatically.

This probably isn’t going to be the deciding factor for most people when choosing a battery chemistry, but if you’re reading up on this because you’re trying to go off-grid and produce all your energy from renewables, it’s something to consider.

What Are The Disadvantages Of LiFePO4 vs. Li-ion?

Of course, where there are advantages there are always a few disadvantages.

Li-ion usually has higher energy density than LiFePO4

Energy density means “the amount of energy the battery can store relative to its size or weight”. High energy density is good because we can store more energy in the space that we have available, or use a smaller, lighter battery to store the same amount of power.

The energy density of a LiFePO4 battery is about 40–55Wh per lb (90-120Wh per kg), while the energy density of a Li-ion battery can be from 45Wh right up to 120Wh per lb (100-265Wh per kg).

The reason for this wide range is because, as discussed above, Li-ion is actually a catch-all term for a number of different battery chemistries with different properties.

You strictly don’t need to understand what these numbers actually mean; just note that some kinds of Li-ion battery can store twice as much power as a LiFePO4 battery of the same weight and size (or be half the size and weight, with the same performance), at the cost of a massively shorter lifespan, etc.

Li-ion is smaller and lighter than LiFePO4

Thanks to its higher energy density, a Li-ion battery can be as little as half the size and weight of a LiFePO4 battery with the same capacity.

This is one of the main reasons anyone uses Li-ion. Space-and-weight-sensitive applications, like our slim modern smartphones and laptops, almost always use Li-ion. Likewise, electric vehicles – the lighter an electric car is, the further it can go on a charge.

This goes double for things like drones, where it’s vital to keep the overall weight as low as possible.

Li-ion has a much higher discharge rate than LiFePO4

Discharge rate means the amount of power the battery can provide at once. We talk about discharge rate in terms of “C”. If we say a battery can discharge at 1C, we mean it can discharge its entire capacity in one hour.

In other words, if the battery was 100Ah (amp hours) in capacity and rated at 1C, that would mean the battery could output 100A (amps) at once. 2C means the battery could output its entire capacity twice in one hour, although of course, it would be flat in half an hour.

I.e., a 100Ah battery rated at 2C can output 200A for half an hour; if it was rated at 4C, it could output 400A for 15 minutes.

In reality, it would get slightly less efficient as you pulled more current out of it, but that’s the gist. LiFePO4 batteries are often rated at 1C. Lithium-ion batteries are often rated 3C or higher. This is another reason Li-ion batteries are used in the majority of electric cars, drones, etc.

Which Is Better, Lithium-ion or LiFePO4?

As we’ve seen above, li-ion and LiFePO4 each have advantages and disadvantages that make them better for different applications.

If you’re looking for a battery that can last for years, decades even, you definitely want to choose LiFePO4. Lithium-ion batteries can usually be “cycled” – charged and discharged – about 500 times.

That makes them useless for applications like storing solar power or supplying power to a boat, van, or off-grid cabin. Assuming you cycle the battery every day, it will last less than eighteen months.

LiFePO4, on the other hand, is good for 2,000 cycles minimum, which is about five and a half years. If you can afford to fit a larger LiFePO4 battery bank and not discharge it very deeply, there’s no reason it won’t last 5,000 or even 10,000 cycles, which is up to twenty years.

If you want to store power from an array of solar panels or a wind generator, in an off-grid home, van, or cruising sailboat, LiFePO4 is unquestionably better.

Another reason to choose LiFePO4 over li-ion for a boat, van, or home is that it’s safer.

You’ve probably seen articles on the news about lithium batteries in phones or scooters bursting into flames. None of these were LiFePO4 batteries – it’s a stable battery chemistry that requires very extreme conditions to ignite.

You need to raise the internal temperature of a LiFePO4 battery to about 500-540°F / 260-280°C before it enters “thermal runaway” and sets on fire.

Likewise, if you overcharge a LiFePO4 battery, it won’t set on fire – you will reduce its capacity or damage it beyond repair, but your home or boat will be safe.

The ABYC recently released an investigation in partnership with the IAAI (a global organisation of over 10,000 fire service professionals) that found there have been zero recorded LiFePO4 fires to date on boats, anywhere in the world.

Lithium-ion, on the other hand, absolutely can and does set on fire when over-charged, pierced, or even shorted out. It only needs to hit roughly ~260°F / 130°C to enter thermal runaway.

Here’s just one example of where a lithium-ion fire resulted in tragedy. It’s “safe enough” that we still use it for phones and laptops, but it’s definitely something to factor in.

If you need the absolute smallest, lightest battery, then lithium-ion might be a better choice.

Lithium-ion can have up to double the energy density of LiFePO4. That means it can be as little as half the size and weight of a LiFePO4 battery with the same capacity.

Portable devices like smartphones, smartwatches, and laptops always use lithium-ion for this reason.

If you need the absolute maximum power (current) out of your battery, lithium-ion might be the best option.

All lithium batteries can output huge amounts of current compared to their old-fashioned lead-acid cousins. LiFePO4 batteries can happily output “1C”, which means, for example, a 200 amp-hour LiFePO4 battery can output 200 amps more or less continuously until it goes flat. That’s a lot of current, more than enough for most applications.

But sometimes you need the absolute maximum current from the smallest, lightest battery.

Say you’re designing a drone – you need huge amounts of power to take off and fly around, but at the same time, you need to keep the weight as low as humanly possible otherwise you need even more power; and then bigger, heavier motors to generate enough lift, and a thicker, stronger airframe to support the load.…

Or you’re building an electric car, and you want masses of torque and acceleration when you put your foot down. Chances are, your design will work better if you use a lithium-ion battery.

Lithium-ion batteries can often output up to 3C, which means a 200 amp-hour lithium-ion battery might be able to output 600 amps continuously until it goes flat (in 20 minutes).

As a side note, as we write this article in late 2023, some electric car manufacturers are actually moving to LiFePO4.

They’ve been popular in Asia for a few years now, but 99% of American and European electric vehicles use lithium-ion because it’s lighter and can output more current.

We would love to be able to say the change is due to rising awareness of the horrible environmental and human cost of mining cobalt, but actually, it’s mostly just because cobalt is becoming more expensive.

If you don’t know whether you should choose lithium-ion or LiFePO4, you should almost certainly choose LiFePO4.

LiFePO4 is the best choice for most people – it lasts between five and twenty times longer than lithium-ion but costs about the same up-front, meaning it really costs at least five times less than lithium-ion over its lifespan.

It’s dramatically safer – there are no confirmed cases of a LiFePO4 battery setting on fire from overcharging, piercing, or other abuse, where lithium-ion batteries have famously burst into flames on a number of occasions (remember the whole Samsung phone scandal?).

Conclusion: LiFePO4 vs Lithium-Ion Batteries

In conclusion, there is very little competition when it comes to LiFePO4 vs Lithium-Ion for use in marine environments. In our opinion, the positives of LiFePO4 far outweigh the negatives, especially when it comes to safety, and we have found our LiFePO4 set-up to be far superior than any other batter set-up we’ve had onboard.

There are still a number of applications where lithium-ion is arguably the best choice – the smartphone you use every day is powered by one – but unless you absolutely must have the smallest, lightest battery, LiFePO4 will still give you a very powerful, energy-dense battery at 2/3rds the size and weight of a comparable lead acid battery, and at 1/5^th to 1/20^th the lifetime cost of lithium-ion.

If you’re looking for a LiFePO4 battery set-up to meet your needs then we can highly recommend speaking to the guys at Battleborn, who can give you the best advice on the right set up for you. Their batteries are the best we’ve seen and we have had amazing support from them throughout.

About the author

Adam Whistler is a battery expert who has been interested in portable power for over two decades. He finds batteries unreasonably fascinating and will talk to you about them for hours if you let him. Adam’s latest battery project was a 20kWh LiFePO4 installation on a world-cruising catamaran.

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