LiFePo4 Battery

What is LiFePo4 Battery?

By March 29, 2021April 24th, 2021No Comments
what is lifepo4 battery

Have you come across the term lifepo4 battery and did not know what that is? You have come to the right place. Our knowledgeable engineers will attempt to answer your question. The importance of batteries cannot be overlooked for the advancement of modern-day engineering systems. It is batteries that perform numerous key functions ranging from providing power to automobiles, battery storage systems to the development of mission-critical backup systems.

This extensive usage of batteries requires their high performance, reliability, and low maintenance coupled with fast-charging capabilities. Traditionally, lead-acid batteries have been a common choice for battery needs. However, due to their inefficiencies in the above-mentioned parameters, their usage is becoming increasingly obsolete.

So What is LiFePo4 battery? It is necessary to make one thing clear right at the beginning. LiFePo4 is one type of battery chemistry used in cells to make a battery. In other words, cells made of LiFePo4 chemistry are assembled to make a battery, hence LiFePo4 battery. LiFePo4 stands for Lithium Iron Phosphate and we will discuss its benefits below.

The present-day requirements demand a battery that has high resilience and optimum performance. To meet this growing demand, Lithium Iron Phosphate (LiFePo4) batteries are a very promising candidate, which provides a reliable operational endurance with fast charging capabilities.

History of LiFePo4 Battery

Lithium Iron Phosphate (LiFePO4) batteries, commonly known as LFP batteries, were first introduced as an optimization in the existing Lithium-Ion batteries in 1996. It was then discovered that phosphate materials can be applied as a cathode in the Li-ion batteries.

Lithium-Ion batteries are being used extensively, but their main drawbacks are efficiency problems and safety issues. These problems in Li-ion batteries have given rise to phosphate-based lithium chemistries. LiFeP04 batteries have an iron phosphate cathode and a graphite anode.

The typical energy density of these batteries lies between 90-125 Wh/kg, with the nominal voltage range of 3.2 Volts and a charge and discharge rate of 1 and 1.25 C respectively. Nevertheless, manufacturers all over the world are working on new solutions to increase it. We at EcoBatt Solutions have managed to go further than the average with the energy density of 153Wh/kg.

strengths and weaknesses of lithium based battery chemistries

Strengths and weaknesses of lithium based battery chemistries.

Operation

The operation of LiFePo4 batteries is very similar to Lithium-Ion Batteries. The two operational phases, charging and discharging are elaborated on below:

Charging LiFePo4 Battery

The charging process is completed in two phases. In the first phase, the supply of constant current (CC) completes the sixty to seventy percent charging state (SOC). The next phase occurs when the voltage reaches the upper limit of 3.65V. It is when constant voltage (CV) takes over from constant current (CC) to complete the remaining 30% to 40%. While the voltage is slowly rising to the 3.65V upper boundary, the current is slowly decreasing. Imagine a train arriving into the station slowing down before it fully stops. The speed at which a LiFePo4 battery is charged depends on the rate of current used (C-rate).

Discharging LiFePo4 Battery

The nominal battery energy per unit volume (volumetric density) is measured in Watt-hours per liter. Energy density is directly proportional to energy storage capacity of the battery. LiFePO4 batteries have a high energy density ranging from 280 to 350 Wh/L, which allows them to perform over a long duration and discharge efficiently. The battery discharge period is relatively long compared to other conventional battery types. DoD (Depth of Discharge) is also superior. This means that some LiFePo4 batteries can be discharged to the depth of 95% of the rated capacity.

Advantages of LiFePO4 Battery    

Phosphate based lithium iron batteries have numerous advantages over other battery types based on their performance and durability. Some of the key advantages are described below:

Safe Operation

A common problem associated with the application of batteries is their chemically hazardous nature. It has been reported in many cases throughout the world, that unsafe handling of batteries was the reason behind accidents such as explosions and fire due to overheating. In this case, lithium iron phosphate batteries are extremely safe.

They do not get overheated with continuous operation because the oxygen is tightly packed to the molecule. There is no danger of explosion/overheating like there is with Lithium-Ion or other conventional batteries. The chemical composition of LiFePo4 batteries makes them safe from thermal runaways. Therefore, they are an ideal option for domestic and vehicle battery requirements.

High Performance in Extreme Conditions

LiFePo4 battery technology exhibits high endurance in extreme conditions such as extreme temperatures, where the performance of other battery chemistries typically declines. These batteries show remarkable charging and discharging properties ranging from temperatures even above 40 degrees Celsius (140˚F) to temperatures of minus 10 degrees Celsius(14˚F). Excellent stability even at extreme temperatures helps in uninterrupted battery operation for high performance needs.

Tubular LiFePo4 cells are assembled to form a battery

Tubular LiFePo4 cells are assembled to form a battery.

Fast Charging

Fast charging is a salient feature of LFP batteries. They require a lower charging time. This is mainly due to their high energy density, which enables them to get charged up faster compared to other chemistries. This is particularly important in mission-critical industries. Li-ion batteries in our mobile phones can equally be charged up quickly. However, it is done so at the expense of lower life cycles. Have you noticed that your mobile phone goes flat way too soon in a year or two when using fast chargers? This issue is less apparent in LiFepo4 batteries.

Longer Life Cycle

The durability of any battery depends on the number of its life cycles. The conventional chemistries enable the battery to give 500 to 1200 hundred full cycles. A full cycle means that the battery is fully discharged and then fully charged to its original state. So, if you discharge and charge your mobile phone once a day, you would get 365 full cycles a year. LFP batteries offer a longer life cycle of around 2000 to 5000 cycles, which gives the customer value for money compared to other chemistries. The life cycle can be further extended up to 8000 cycles by charging and discharging at lower currents.

Consistent and Stable Discharging

One of the main advantages associated with LiFePo4 batteries is the stable discharging that does not allow the voltage value to drop like in other battery technologies. This is due to the fact that LFP batteries maintain their nominal voltage even at their lowest charging values. The peak value for their voltage output is 3.65V normally but they keep 3.2 volts on output even at the lowest charging point.

High Energy Density

The key feature responsible for optimum performance in Lithium Iron Phosphate batteries is their high energy density. Being based on the lithium phosphate chemistry, these batteries have a high Ampere hour rating, which consequently gives them higher energy density. That is around four to five times more than solution-based conventional batteries such as Lead-acid compositions etc. The high energy density allows them to survive a long period of time on shelfs without any significant impact on performance degradation.

Environment-Friendly Composition

One of the most important benefits that are achieved with LiFePo4 batteries is their environment-friendly nature. There are made of nontoxic materials that are recyclable and do not pollute the environment. This is contrary to other compositions (such as lead), which pose a serious risk to the environment. Wider use of batteries in our everyday lives will depend on our ability to recycle and dispose of them safely. LFP batteries are a fitting candidate to deliver a stable supply of energy without harming our planet.

Drawbacks

With the numerous benefits of the LFP batteries and several edges on the peer chemistries, there also some drawbacks associated with them. These include the sluggish and decreased performance under the lower temperature ranges below -10 degree Celsius(14˚F). The other disadvantages include lower tapped density and higher costs of these batteries.

Applications and Future Prospects

The future seems very bright for the LiFePo4 technology. Researchers are working on more diverse applications of these batteries apart from the current applications in which they are being used. Currently, LFP batteries are being mainly used in high-performing devices such as marine electronics, automobiles (e-bikes and electric cars, etc.), energy storage systems, and telecom devices.

Apart from these, their most common application is in the form of small battery cells with a nominal voltage of 3.2 Volts. The mini cells can be used in a number of ways, mostly in electronic equipment and portable machinery. Battery engineers and scientists are working on developing solutions that can reduce the charging duration for LFP further.

An example of such developments is the MIT research lab, where the scientists succeeded in lowering the charging time for the LFP by 100 times. They achieved this through improvement to the FePO4 cathodes. Similarly, the future development in fabrication techniques could reduce the cost of production for these batteries.  The application of LFP technology in the renewable energy sector for backup storage systems can lay the foundation for sustainable energy development.