Several Factors that Limit the Energy Density of Lithium Batteries

The rapid development of electric vehicles and other electric devices has created a more significant need for better energy storage solutions. Pressure has been exerted on the performance of lithium batteries, with more being created to meet the rising needs.

Constant battery volume and weight are the main factors determining such performance. And in this case, the battery's energy density plays the primary role.

The higher the energy density, the stronger the battery. And lithium-ion batteries seem to have the best offers.

Today, we shall be looking at factors that affect the energy density of these batteries. We want to see how these factors can increase or reduce it.

Keep reading.

What is Energy Density?

Before getting into the details, it's extremely crucial that we understand what energy density means in lithium batteries. Discussing the factors affecting it would be hard without first understanding what it means.

Energy density is the amount of energy stored per unit amount of space. It is also the mass of matter. This parameter is represented using watt-hours per kilogram (Wh/kg).

Another way to look at energy density is the amount of electrical energy a battery can release per unit volume. It can also be defined in terms of the mass of the battery on average.

 Energy density in lithium batteries comes in two types: the weight energy density and the volume energy density. The earlier is calculated as the battery capacity x discharge platform/weight with Wh/kg as the basic unit. The latter is capacity x discharge platform/volume with Wh/l as the basic unit.

A battery with the highest energy density stores the most power per unit volume or weight. This is why small lithium-ion batteries perform better than larger and heavier lead-acid batteries.

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Factors Affecting Energy Density

It is crucial to have and maintain a high energy density in batteries. It's all about getting the best performance from your batteries.  

We now understand what energy density is and the role it plays in battery performance. So, what are the factors that affect it? Understanding these factors can help you to make more informed decisions and get the most from your batteries. They include the following:

Anode Materials

The negative electrode materials carry the highest energy density in a lithium battery. This is the component that performs most of the tasks when the battery is discharging on a load, which is why it has such performance needs.

Sing high-energy density anode materials can increase the energy density of the entire battery. The cathode also plays a similarly important role in the performance of these batteries.

Cobalt-oxide batteries have the highest energy density. They use cobalt oxide as the cathode and graphite carbon as the anode. And because of this high energy density, these batteries are popular in devices that demand more energy, including all the popular electronic devices today.

As stated earlier, the active cathode material is mostly made of metal oxide. It is crucial to find the most suitable anode materials for the same.

The active anode material is generally carbon-based materials.   They are mostly graphite, silicon, or a combination of both.

Graphite has become the most popular option since it offers more electrical conductivity, low cost, and stable structure. Silicon anodes, on the other hand, have a higher energy density, but they have issues with volume expansion and short life.

Another popular option for the anode material is graphite with a small amount of silicon. This combination creates the best performance characteristics and energy density.

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In short, the anode material significantly impacts lithium batteries' energy density. Manufacturers are always looking for ways to improve performance using the best materials on the market as single materials. However, combining different materials creates the best-performing batteries.

When buying batteries, therefore, ensure you understand the anode material. This can help you get the most performance from your batteries.

Voltage Platform

Lithium-ion batteries continue to take over the world with incredible performance and long lifespan. They offer the highest energy density with generally more power than other batteries.

The voltage is not constant when they are in constant current charge and discharge process. When in the constant current discharge, the voltage changes can decline, steady, and then decline again to a point where it is no longer discharged.

Such constant current charge and discharge mean the voltage has a smooth process. The steady value is, therefore, the charge and discharge platform.

Batteries with more stability and longer time on this platform promise the best level. The battery is to use that period of voltage stability.

The choice of charge and discharge cut-off voltage and the system used in charging also has an impact on the battery's energy density. This is because it directly touches the life cycle of that battery.

When there is a blind increase in the working current of the battery, the charging cut-off voltage is increased, or it can do the opposite and decrease the voltage, which decreases the battery's energy density and its general performance.  

Different lithium batteries have different electrochemical systems, which affect the voltage platform creating variations in energy density. Therefore, choosing the right battery based on its voltage platform determines how much performance you will get from it.

Productions Process

The production process of lithium batteries largely affects their energy density. There have been several advancements in the manufacture of these batteries over the years, mostly touching their chemistry.

Engineers experiment with different cathode and anode materials to discover the best electrochemical combinations and alter the energy density of these batteries, among other parameters. Lithium cobalt-oxide batteries, for instance, are currently the ones with the highest energy densities. They use cobalt oxide on the cathode and graphite carbon as the anode.

Using high-nickel positive and silicon-carbon negative electrodes creates batteries with the highest energy densities. But that is not enough. The way these materials are grouped and used also determines how much they will work.

Grouping battery packs by arranging single-cell batteries and modules is another way to create more energy density. And then, slimming is done by optimizing the layout structure and the topology. This is why lithium batteries offer the best performance with excellent energy density.