What’s the difference between 3.2V and 3.7V lithium batteries

Sometimes when you look for lithium batteries, you may notice there are 3.2V and 3.7V lithium batteries. Maybe you found it a little difficult to understand. Do you know the difference between them?

The main reason is that they are made from different materials. 

Lithium batteries of 3.2V are lithium iron phosphate batteries, whose positive electrodes are mainly made of chemical LiFePO4. Due to the chemical characteristics of the raw material, a single cell produce voltage of  3.2V. 

Lithium batteries of 3.7V are lithium polymer batteries (common ternary lithium battery, lithium ion battery, such as cell phone, wireless headset, smart watch battery, etc.), the main chemical raw materials of positive electrode include LiCoO2, LiNiO2, LiMnO2 and manganese nickel cobalt composite oxide, etc. Due to the characteristics of their own chemical substances, a single cell produce voltage of  3.7V.

3.2V or 3.7V are the nominal voltages of a single cell. 

The full-charge voltage of 3.2V batteries is 3.65V, while the full-charge voltage of 3.7V batteries is 4.2V / 4.35V / 4.45V;

3.2V and 3.7V both refer to the cell discharge curve, which is the average of the curve from the initial full-charge voltage to the discharge termination voltage.

LiFePO4 battery and Ternary lithium battery are widely used in our life. Do you know anything about these two kinds of batteries?

In this article, let’s compare these two batteries and learn more about their advantages.

What Is LiFePO4 Battery and Ternary Lithium Battery?

LiFePO4 battery, also LFP battery, stands for lithium iron phosphate battery. It is one type of lithium battery that utilizes lithium iron phosphate as the positive electrode material.

Ternary lithium battery is also a type of lithium battery. Its positive electrode material is made of a combination of nickel, cobalt, and manganese/aluminum.

Both LiFePO4 battery and Ternary lithium battery are commonly used in solar energy systems, UPS, and many other applications.

The Comparison Between LiFePO4 Battery and Ternary Lithium Battery

Safety  

Lithium iron phosphate battery is chemically stable and has great safety performance. The internal chemical composition of LiFePO4 batteries begins to decompose only when the temperature reaches 500-600℃. In addition, even if the LiFePO4 battery is damaged, no oxygen molecules will be released and no violent combustion will occur.

The thermal stability performance of the Ternary lithium battery is inferior. The battery starts to decompose at about 300℃. 

Energy Density

The most critical indicator to evaluate the performance of a battery is energy density. The energy density of LiFePO4 is about 140Wh/kg.

The energy density of the Ternary lithium battery is about 240Wh/kg. Under the same weight, the energy density of the Ternary lithium battery is 1.7 times that of the LFP battery.

Low-temperature Performance

The low-temperature performance of the LiFePO4 battery is inferior to that of the Ternary lithium battery. The low-temperature limit of the Ternary lithium battery is -30℃. Its discharge performance at low temperatures is good. On the other hand, the temperature limit of the LiFePO4 battery is -20℃.

Lifespan

The LiFePO4 battery has a long lifespan, which is about 3,500 cycles. However, the life of the Ternary lithium battery is shorter than that of the LiFePO4 battery. It reaches about 2,000 cycles.

Summary

Both LiFePO4 battery and Ternary lithium battery have their advantages. If you need a battery with high safety, you can choose lithium iron phosphate batteries. If you want to use the battery at low temperatures, you can go for Ternary lithium batteries.