Complete guide to energy density of lithium ion battery

1. What does energy density mean
2. What is high energy density
3. What is the difference between power density and energy density
4. Which battery has the highest energy density
5. Why do lithium-ion batteries have a high energy density
6. What affects the energy density of lithium ion battery
7. How do you increase the energy density of lithium ion battery
8. Do energy density matter in a battery
9. FAQs
   1. Is high power density good
   2. Does high energy mean high risk
   3. Does high energy density of lithium ion battery means more cost

When choosing a battery, do you consider the energy density of the battery? One of the reasons why lithium-ion batteries are so popular is the energy density of lithium ion battery. This article will explain the definition of energy density, the influencing factors, and whether the energy density of lithium ion battery is the highest, etc. that everyone is curious about.

What does energy density mean

The energy density of a system refers to its ability to store energy. A substance with a high energy density holds more energy than a low one. Energy density can be volumetric (Wh/L) or gravimetric (Wh/kg).

What is high energy density

Having a high energy density allows a system to store a large amount of energy in a relatively small mass. This means that the higher the energy density of the battery, the more electricity can be stored per unit volume. It is possible to perform work for a long period using a device with a high energy density but a low power density.

Battery technology today aims for high energy density. So that they can support the devices longer. Additionally, the high energy density means that you will be able to use smaller batteries, such as in Tesla cars, thereby saving space.

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What is the difference between power density and energy density

When talking about batteries, energy density and power density are two frequently mentioned quantities, and power density and energy density are not directly related. Energy density (Wh/kg) refers to the energy stored per unit weight of the battery, 1Wh is equal to 3600 joules (J) of energy.

When we choose batteries for application scenarios such as golf carts, electric vehicles or portable devices, we have to consider the energy density of the battery. The energy density of an ordinary lead-acid battery is about 60Wh/kg, the energy density of lithium ion battery is around 270 Wh/kg.

It is obvious that under the unified specification, the weight of lithium-ion battery is lighter than that of lead-acid battery, and it is only one-third of lead-acid battery, and this is one of the reasons why lithium ion battery applications are more widespread. In addition, the cycleability of lithium-ion batteries is much higher than that of lead-acid batteries, so lithium-ion batteries are currently the first choice for developing electric vehicles.

Power density (W/kg) refers to the rate at which energy can be output per unit weight of battery when discharged. The energy density is determined by the material properties of the battery, and the power density is also determined by the material properties. Power density actually describes the rate performance of the battery, that is, how much current the battery can discharge.

Power density is very important for battery development and electric vehicle development. If the power density is high, the electric vehicle will accelerate very fast. The power density of ordinary lead-acid batteries is generally only tens to hundreds of watts/kg, which is a very low value, indicating that lead-acid batteries have poor high-rate discharge performance, while the current power density of lithium-ion batteries can reach several kW/kg.

Which battery has the highest energy density

The lithium-ion battery is the clear winner when it comes to high energy density. Energy density of lithium ion battery have transformed the way we live. Previously, lead-acid batteries were used; these can store around 60-70 W-h/kg of energy. On the other hand,  energy density of lithium ion battery have 250-325 W-h/kg energy density.

Here is a comparison of different batteries’ energy densities:

Specification	Lead Acid	NiCd	NiMH	Li-ion
Energy Density (Wh/kg)	60-70	50-150	140-300	250-325

The above table clearly shows that lithium-ion batteries outperform their competitors because of the advances in their chemistry.

Why do lithium-ion batteries have a high energy density

Lithium-ion batteries are a type of batteries that use lithium metal or lithium alloy as the negative electrode material and use a non-aqueous electrolyte solution. Energy density of lithium ion battery is determined by its power generation principle, because the lithium in the lithium battery is an atom with a proton number of 3. Under the same mass, the number of moles of the lithium battery is more, and the energy generated is stronger, so the energy density of lithium ion battery is greater.

The further down the periodic table is used, the less available electrons are in the atom, and the less electrons are provided per unit mass. The choice of this element determines the upper limit of the energy density of a battery. Therefore, in the continuous progress of the battery, people continue to try to use the elements higher in the periodic table. From lead, to zinc, to sodium, to lithium.

What affects the energy density of lithium ion battery

The amount of active material of the positive electrode and the selection of the specific capacity of the active material may be important factors affecting the energy density of lithium ion battery. Generally speaking, the proportion of positive and negative active materials increases, and the energy density of lithium ion battery increases.

In addition to the active materials of the positive and negative electrodes, electrolytes, separators, binders, conductive agents, current collectors, substrates, shell materials, etc. In order to ensure a safe metal casing, a protection circuit that cannot be overcharged and overdischarged, etc., these materials are all auxiliary. The larger the proportion of them, the smaller the energy density of the battery. If the weight of these materials can be reduced without compromising the performance of the battery, it could also improve the energy density of lithium ion battery.

How do you increase the energy density of lithium ion battery

The liquid electrolyte in traditional lithium-ion batteries limits their energy potential. The use of solid-state electrolytes can, however, opens up the possibilities to enhance the energy storage capabilities of Li-ion batteries without minimum security risks.  It has been done in solid state lithium ion battery that display much higher energy density than the traditional li-ion batteries, and here are top 10 solid state battery manufacturers in China, hope to bring you useful information.

Do energy density matter in a battery

The efficacy of a battery depends on its ability to retain more energy compared to its size. High-energy density batteries are in demand for devices that need constant power usage.

Further, with high energy density, you can reduce the size of the batteries. It solves the pertinent problem of space utilization by these batteries. For instance, Tesla cars save more space because of Li-ion batteries.

So here is the thing, can you live with a small, lightweight battery that provides power for a long time, or would you prefer a heavy battery that provides little power?  The former is the choice most people would make. This is why we need a high energy density.

FAQs

Is high power density good

As mentioned earlier, power density refers to the maximum amount of energy that can be discharged from a battery. It is possible, for example, for a tiny capacitor to produce as much power as a large battery.

The requirement of high power density depends on the type of a system or tool being energized. Mobile phones, for example, rely on constant, long-term discharges of energy in order to function. Therefore, they don’t require such high power density. On the other hand, power tools, such as jigsaws and circular saws require batteries that can release a lot of energy at once.

Does high energy mean high risk

The more energy that a battery holds, the more power it can release. It is, therefore, possible that something can go wrong and result in a high energy burst that is potentially dangerous. Additionally, due to the presence of highly volatile electrolytes in Li-ion batteries, the possibility of catching fire is pretty high.

Does high energy density of lithium ion battery means more cost

The energy density of lithium ion battery is not a direct factor in cost. Since 2020, due to the impact of the new crown epidemic, raw material companies have failed to realize the expansion plan as expected, resulting in a shortage of raw material imports and tight supply. At the same time as the demand has increased sharply, the shortage of supply is the reason for the rise of raw materials for power lithium batteries.

In order to meet this challenge, odm best lithium battery manufacturer will choose two angles to maintain a reasonable gross profit margin, one is to reduce manufacturing costs, and the other is to increase product prices. Technology advancements may further reduce the cost of high energy in the coming years.

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