Everything You Need to Know About Lithium Iron Phosphate Batteries

Lithium iron phosphate (LiFePO4) batteries are a newer type of lithium-ion (Li-ion) battery that experts attribute to scientist John Goodenough, who developed the technology at the University of Texas in 1997. While LiFePO4 batteries share some common traits with their popular Li-ion relatives, several factors several factors distinguish them as a superior alternative. Explore what LiFePO4 batteries are, how they work and their advantages to decide if the technology is right for you.

What Are Lithium Iron Phosphate Batteries?

LiFePO4 batteries are rechargeable power sources using lithium ions in a multicell design. The technology relies on interactions a graphite component and a Lithium Iron Phosphate component. Each LiFePO4 cell can generate about 3.3 volts of electricity, so manufacturers combine multiple cells to reach the necessary level for delivering adequate voltage and current. These cells combine with a circuit board to regulate charge rates, discharge rates, and safety.

How Lithium Iron Phosphate Batteries Work

Each battery has an anode, electrolyte, cathode, separator, and a positive and negative current collector. The anode and cathode are responsible for lithium storage. During discharge, the anode's lithium atoms undergo ionization and separate from their electrons. These travel along the electrolyte to the cathode, rejoining their electrons. 

This movement produces current, which passes it through the device to its partnering current collector. During recharging, the process reverses. The cathode releases the ions, and the anode receives them.

4 Benefits of Lithium Iron Phosphate Batteries

LiFePO4 batteries have numerous advantages over their Li-ion predecessors.

1. Enhanced Safety

Increased safety is the primary benefit of LiFePO4 technology.

Unlike traditional lithium-ion batteries, LiFePO4 options are less susceptible to overheating and thermal runaway — the cause of well-publicized hazardous incidents with Li-ion batteries. The higher thermal stability means a substantially reduced fire or explosion risk. With respect to Lead Acid batteries, LiFePO4solutions do not emit toxic gases.

These features make LiFePO4 batteries suitable for power generation in more enclosed spaces with limited ventilation, including residential applications.

2. Improved Depth of Discharge

Depth of discharge is another area where LiFePO4 batteries outperform their counterparts, including conventional Li-ion technology. The term defines the percentage to which you can discharge the battery without affecting its integrity. Exceeding the recommended level can result in permanent battery damage.

A higher depth of discharge means you can use more of the energy your battery stores, making it viable for longer use before recharging. LiFePO4 solutions offer a complete 100% depth of discharge. Conversely, lead-acid options typically feature only 50%, and traditional Li-ion batteries range between 80% and 95%.

3. Reduced Self-Discharge

LiFePO4 batteries continue to expend their energy during storage periods, a phenomenon called self-discharge. However, they do so at a significantly lower rate than lead-acid, nickel-cadmium (NiCad) and conventional Li-ion batteries. 

Lead-acid batteries self-discharge at about 4% weekly and NiCad power sources at about 1% to 3% daily. A Li-ion battery self-discharges at an average rate of about 5% monthly. As a result, all three will require more frequent charging, even when not in use.

With LiFePO4 batteries, you can expect a monthly self-discharge rate of about 3%. That fact allows extended storage without the need to recharge.

4. High Energy Density

Rechargeable LiFePO4 batteries have a high energy density, which is the electricity they provide and energy they can store in comparison to their mass. That means a smaller battery with a high energy density offers more electricity and storage than a similarly sized one with a lower energy density. . Although their energy density isn’t as high as Lithium Ion batteries, their energy density is very high and well above Lead Acid batteries.

Experts measure energy density in watt-hours per kilogram (Wh/kg), and LiFePO4 batteries range between 90 and 165 Wh/kg. This range makes them ideal options for applications like solar energy and electric vehicles.

Possible extra benefits:

Temperature Range: They can operate effectively in a wider temperature range, often from -20°C to 60°C, making them suitable for various environments.

Voltage Stability: LiFePO4 batteries provide stable voltage during discharge, which is beneficial for applications needing consistent power output.

Environmental Impact: They are considered more environmentally friendly since they don't contain toxic heavy metals like cobalt or nickel.

Cost: Generally, LiFePO4 batteries are less expensive to produce compared to some other lithium-ion chemistries, although their initial cost can still be higher than lead-acid batteries.

How Long Do Lithium Iron Phosphate Batteries Last?

Manufacturers often express the life spans of batteries as how many charging cycles they support. A cycle occurs when a battery goes from fully charged to completely discharged to fully charged again, though some manufacturers consider any recharge a cycle.

Cycle life is the number of times a battery can be charged and discharged without experiencing performance loss. A longer cycle life typically translates into extended life spans which translates into lower operational cost due to longer replacement intervals. The number of cycles you'll ultimately receive from the battery depends on factors like charging frequency, operating conditions, and the battery's capacity and design so replacement times will vary depending on the application.

Traditional lithium-ion batteries generally feature a cycle life ranging between 300 and 500 cycles. Conversely, LiFePO4 batteries typically offer a much longer cycle life at an average of 3,000 cycles.

How to Maintain a Lithium Iron Phosphate Battery

The following tips can help keep your LiFePO4 batteries healthy and may positively impact their life span.

1. Choose a Cool, Dry Storage Space

Long-term exposure to heat and moisture can affect the battery's capacity, performance and life span. When storing batteries for an extended time, choose a dry, cool location and avoid direct sunlight.

2. Use Compatible Materials

Charging your battery and keeping its terminals clean are highly recommended, but choosing compatible materials is essential to prevent unintentional damage.

Only use chargers that specifically come with your battery or list it as a supported model. When cleaning, opt for a soft brush or clean cloth, and avoid any abrasives or harsh chemical removers.

3. Follow the Manufacturer's Recommendations

Your product's owner's manual is the best source of information on how to store and charge your battery properly.

Generally speaking, you should store batteries separately from the products they power if you don't need them for an extended time. Many manufacturers recommend charging or discharging the battery to about 50% capacity before storage. 

Since these batteries continue to self-discharge in storage, it's best to check their charge level at least every 6 months and recharge to 50%. Storage in warmer locations and climates may result in faster self-discharge and require more frequent monitoring.

View Our Battery Power Solutions

Multilink has been a leading developer and manufacturer of telecommunications and intelligent traffic system solutions since 1983. We back our field-proven and innovative designs with superior customer service and a passionate commitment to quality.

Multilink has created a robust new power solution with the maintenance-free PantheonCell™ LiFePO4. This revolutionary technology features lithium iron phosphate, delivering consistent performance, long runtimes and increased safety over other battery types. View all our PantheonCell™ configurations online to request a quote, or contact us for personal assistance.