IOT

Introduction to Lithium-iron Phosphate Battery

In this tutorial, we are discussing what a Lithium Iron Phosphate battery is? Its cell configurations, advantages, and applications.

LiFePO4 Batteries | Lithium Iron Phosphate Batteries Advantages And Disadvantages | Lithium Iron Phosphate Battery Discharge Rate And Their Future

What is a Lithium Iron Phosphate battery?

Lithium iron phosphate (LFP) batteries also known as lithium ferrophosphate batteries are a type of lithium-ion battery that is capable of charging and discharging at high speeds compared to other types of batteries. Lithium iron phosphate batteries are a type of lithium-ion battery that stores lithium ions using lithium iron phosphate as the cathode material. Graphite is commonly used as the anode material in LFP batteries. LFP batteries have a high current rating, good thermal stability, and a long lifecycle due to its chemical makeup.

After the discovery of phosphate as a cathode material for Li-ion batteries in 1996, the first model of the lithium iron phosphate battery was created. This form of battery has become more efficient as coatings have improved and nano-scale phosphate has been used.

The main difference between lithium iron phosphate batteries and other lithium-ion batteries is that LFP can deliver a steady voltage and has a larger charge cycle, ranging from 2000 to 3000 cycles. LFP batteries are safe for the environment and architecturally sound. They have a low discharge rate and a low energy density. They don’t get hot easily and stay cold compared to other batteries. The battery’s chemistry prevents thermal runaway, therefore it is safe.

LFPs have found use in automobiles, bicycles, and solar gadgets due to their steady voltage and safe discharge. They’re also utilized as a cheaper alternative to expensive lead-acid starter batteries. They’re ideal for applications that demand a lot of current and endurance. Because of their small weight and ability to deliver massive amounts of energy, they are simple to store and transport. They are commonly found in portable electronic devices such as laptops and cell phones.

This battery is used in high-power applications such as electric vehicles, power tools, and RC hobby vehicles. These batteries have a long service life and are very efficient. They do not need to be charged. Due to the usage of nano-scale cathode material, these batteries have high electrochemical performance with low resistance. 

Features:

  • Better power density
  • Low discharge rate
  • Flat discharge curve
  • Less heating
  • Higher number of charge cycles
  • Increased safety

The key difference between lithium iron phosphate batteries and other Li-ion batteries is that lithium iron phosphate batteries may provide a consistent voltage and a relatively long charge life of 2000-3000 cycles.

These batteries are stable and safe for the environment. They discharge at a slower rate and have a lower energy density. These batteries do not overheat and are much cooler than ordinary batteries.

Lithium Iron Phosphate batteries are mostly involved in R&D activities. The market entails a wide range of assets, and calculating the return on investment is a time-consuming process.

Cell configuration of Li-FePO4 battery:

cell configuration of Lithium iron phosphate battery

The voltage of the battery can be increased by connecting the cells in series. The battery current will also be boosted by connecting the cells in parallel. Li-FePO4 has a safe operating voltage range of 2.5V to 3.6V. Follow the table below for Li-FePO4 cell setup.

Number of cellscut-off voltageNominal voltageMaximum voltage
1 cell2.5V3.2V3.65V
2 cell5.0V7.4V7.3V
3 cell7.5V9.6V10.95V
4 cell10.0V12.8V14.6V
5 cell12.5V16.0V18.25V
6 cell15.0V19.2V21.9V

1. Cut-off voltage:

The voltage at which a battery entirely drains is known as the cut-off voltage. Discharging the battery below the cutoff voltage of 2.5V may result in irreversible performance loss and battery damage.

2. Nominal Voltage:

The Li-FePO4 has a nominal voltage of 3.2V. It is the battery’s storage mode voltage.

3. Maximum/full charged voltage:

The voltage at which a battery reaches its maximum voltage is known as the maximum/full charge voltage. It is unsafe to charge the battery above 3.65V since it will eventually catch fire.

Life-cycle of Lithium Iron Phosphate technology (LiFePO4)

Lithium Iron Phosphate technology allows the greatest number of charge/discharge cycles. As a result, this technology is mostly used in stationary energy storage systems (self-consumption, off-grid, UPS, and so on) for long-life applications.

The number of cycles that can be completed is determined by numerous factors:

  • Quality of Lithium Cell
  • Level of power in C-Rate (1C rate means full discharge or charge in 1 hour, 2C is the same but in half an hour)
  • Depth of Discharge (DOD)
  • Operational environment: temperature, humidity, etc.

Advantages of Li-FePO4 battery

Lithium Iron Phosphate batteries offered some major advantages which include a high operating temperature range, wide cycling performance, high efficiency, and low internal resistance among others.

  • Very safe and secure technology (No Thermal Runaway)
  • Very low toxicity for the environment (use of iron, graphite, and phosphate)
  • Calendar life > 10 ans
  • Cycle life: from 2000 to several thousand
  • Operational temperature range: up to 70°C
  • Constant power throughout the discharge range
  • Ease of recycling
  • These batteries have a longer life span than conventional lead-acid batteries. It dramatically diminishes the need for battery changes.
  • These batteries operate with lower resistance and hence,
  • Lithium iron phosphate batteries are more lightweight than lead-acid batteries, generally weighing about ¼ less.
  • These batteries offer twice the battery capacity with a similar amount of space

Disadvantages of LiFePO4

  • The low nominal voltage of these batteries saves energy.
  • With aging, you’ll have to deal with balancing concerns, and they have a high self-discharging rate when compared to other batteries.
  • Since lithium iron phosphate/LFP batteries have a low energy density, they require greater protection.
  • These batteries operate poorly in cold conditions and require additional protection and care.
  • Transportation and aging effects are also frequent.
  • One of the drawbacks of LPF is deep discharge and low density. Because of these problems, these batteries are unsuitable for compact devices like cellphones. As a result, LFP batteries are mostly employed in LEVs (low emission vehicles) and electric motorcycles.

Application of Li-FePO4 battery

Because LiFePO4 batteries offer tremendous advantages including high specific capacity and greatly enhanced cycle life, and very low weight, these batteries are ideal for the below applications,

  • Boats/Kayaks
  • Communications Equipment including Ham Radio
  • E-Bikes / E-Scooters / Small Vehicles
  • Electric Golf Caddy
  • used as energy Storage to charge the portable electronics like smartphones, laptops, etc  
  • General Purpose Equipment like audio amplifiers, cell phones, computers, portable projectors, etc. Instrumentation equipment includes various types of sensors used to monitor the environment. 
  • LiFePO4 batteries can be combined with a solar panel and solar controller.  The solar panel can charge the LiFePO4 battery while at the same time providing power to an electrical load.     

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