Lithium-ion Battery Efficiency-Temperature, Calculation, and Comparison

Out of all the rechargeable batteries on the market, lithium-ion batteries have proven to be the most effective. They charge at nearly 100% efficiency compared to the others that charge at 85% efficiency. A battery's efficiency is calculated by dividing the energy powered into the battery by the energy discharged out of the battery. Lithium-ion batteries boast an improved battery technology, a high energy density, and a high CE rating. 

The performance of a lithium-ion battery depends on the collective impact of temperature. This article explains how temperature affects a lithium-ion battery, how to calculate the batteries' efficiency, and comparison with other batteries. 

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Lithium-ion Battery Efficiency- Temperature

Different batteries operate at different temperature ranges. Temperature, both high and low, can significantly affect a battery's lifecycle and storage systems. The main capabilities of a battery that are affected by variations in temperature include performance, lifespan, and safety. A standard lithium-ion battery operates at 20-500c. Below is a summary of the impact of both high and low temperatures on a lithium-ion battery. 

Effects of High Temperatures

High temperatures are the worst enemy of any battery, including lithium-ion and lead-acid batteries. At higher temperatures, the battery's performance and storage capacity increase. This is a result of chemical reactions occurring inside the battery. As the high temperatures increase, the chemical reactions also quicken. According to a study by Scientific Reports, a sample temperature increase from 77degrees to 113 degrees led to a 20% increased battery performance. 

However, increased temperatures are likely to cause rapid battery degradation, which affects the lifecycle of a lithium-ion battery. For instance, at 77oC, a battery is expected to be affected by up to 3.3%, while at 1130C, the battery's lifecycle is affected by up to 6.7%. Even though exposure to high temperatures increases battery performance, prolonged exposure should be minimal or avoided to prevent degradation problems. 

Effects of Low Temperatures

Like high temperatures, prolonged exposure to low/cold temperatures also significantly impacts batteries. At low temperatures, the battery's internal resistance decreases, hence lowering the battery's capacity. It is essential to note the charge level that a battery can accommodate during low temperatures to prevent explosion effects. For example, lithium-ion batteries can be charged from 320F to more than 1130F and be discharged from -40F to more than 1400F. Both high and low temperatures affect battery performance; it is, therefore, essential to consult with your seller/dealer about the system of the battery you are purchasing. 

Lithium-ion Battery Efficiency- Calculation

Battery efficiency is the amount of energy you can get out of a battery during its performance compared to the energy put into it. You can measure the efficiency of a battery in two ways: voltage efficiency and coulombic efficiency.

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Coulombic Efficiency and Voltage Efficiency 

Lithium-ion battery efficiency is the product of voltage efficiency and coulombic efficiency. Coulombic efficiency is the capacity of a battery during charge and discharge. It is simply the measurement of lost electrons during a complete charging cycle. Most scientists always use a coulomb counter to measure the coulombic efficiency. Depending on the results after the measurement, you need to know that the higher the CE, the lower the electron loss, the longer the battery life, and vice versa. 

On the other hand, voltage efficiency is the average voltage during discharging over-voltage average during charging. The difference in voltage during charge and discharge is caused by over-potential. A lithium-ion battery efficiency depends on current, time of float charge, time of discharge, and many more. The five key factors that affect a battery's efficiency include:

1.Charge Current

When operating with lithium-ion batteries, ensure the charge current is at a moderate level to increase the battery's life and performance. If you charge at high currents, you can tamper with the battery's internal chemistry, which may affect its life cycle. If you charge the battery at low currents, you will improve the battery's longevity. However, the outcome is a reduction in its capacity. 

2.State of Charge

The state of charge defines the charge level relative to a battery's capacity. The higher the state of charge, the worse the battery's capacity and vice versa. To maximize a battery's efficiency, ensure you are aware of the battery's state of charge. 

3.Internal Resistance

The internal resistance of a lithium-ion battery is affected by many factors, including size, age, currents, and many more—the lower the internal resistance, the higher the battery's performance. Fortunately, lithium-ion batteries have the lowest internal resistance possible in the market. 

4.Battery Temperature

According to manufacturers, lithium-ion batteries need to be charged at a range of 320F to 123oF and discharged at -40F TO 1310F. They are known to work best at high temperatures. 

5.Battery Age

Of course, as the battery ages, it becomes less powerful and efficient; it may also have an irreversible loss of capacity. Generally, lithium-ion batteries can last for over 3000 cycles if you avoid overcharging, deep cycling, and exposing them to high temperatures. 

Lithium-ion Battery Efficiency- Comparison

As mentioned earlier, lithium-ion batteries are the most efficient batteries out of all the batteries on the market. Their CE ratings range from 99% or more, while other batteries like lead-acid start from 90%. Nickel-based battery charge rate starts at 80%. When compared to the other popular batteries, lithium-ion batteries:

●Have a longer lifespan of about 2000 to 3000 cycles

●Have a longer capacity retention

●Can be partially charged multiple times

●Can maintain high voltage output

●Can operate at higher temperatures

●Can work at lower temperatures

Other batteries like the lead-acid:

●Have a lifespan of 1000 to 1500 cycles

●Have a medium-capacity retention

●Require a weekly overcharge to balance the cells

●Decline in voltage when their state of charge reduces

●It can last up to 2 shifts

If you are considering a battery for your home storage system, there are many options to pick from. While lithium-ion and lead-acid can be effective solutions, lithium-ion batteries are definitely the most recommended for multi-shift operations. They have surged in popularity, therefore becoming the only preferred option for home storage systems.