Lithium Ion Battery Pack

Lithium ion batteries power most of the electronic products around us. They are also used in many industrial applications like production equipment or hybrid or electric vehicles.

Lithium ion battery packs have several distinct advantages compared to other rechargeable battery technologies, such as nickel-cadmium or nickel-metal-hydride. They are powerful and lightweight, with a high charge capacity and long lifespan.

High Energy Density

Lithium ion battery technology has the highest power density of all rechargeable battery chemistries. This allows us to create battery packs with a lot of energy that fit in a small space. It also offers great cycle life up to 500 cycles.

Today’s lithium-ion batteries have an average energy density of about 300 Wh per kg. To meet the needs of electric vehicles and other applications, this needs to be increased significantly.

To raise energy density, engineers can experiment with different electrochemistry, or materials used in the anode and cathode. The most popular battery today uses a lithium cobalt oxide (or LiCoO2) cathode and graphite carbon anode. Its high energy density makes it a good choice for smartphones, laptops, watches and cars.

Another way to increase energy density is to make the battery more compact. This can be achieved by using a thinner anode or cathode material, or by improving production techniques. For example, a company called Amprius claims to have developed a battery with a record-breaking gravimetric energy density of 500 Wh per kg.

This could be an important milestone towards a carbon-free economy, as long range electric vehicles and electric aircraft require very Li-ion battery pack high energy densities. However, there are still several other metrics that need to be improved, such as temperature operating window, thermal performance and charge/discharge rates.

Long Lifespan

Unlike nickel-metal hydride, lithium batteries do not develop age-related degenerative effects that reduce runtime. However, like any battery pack, recharging it too frequently can significantly decrease the lifespan.

The longevity of a lithium-ion battery pack is dependent on the quality of its construction and components. A quality lithium-ion cell should be able to sustain more than 100 discharge cycles with minimal loss in capacity. This depends on the cell chemistry, pack design and usage environment. Some battery manufacturers use special materials to prevent cathode dissolution. This can extend the life of a battery pack and increase its energy density, without compromising safety.

Although cobalt aluminum oxide is the most common lithium-ion chemistry, newer battery technologies are expected to unlock present limits on energy storage. Some of these are based on disruptive active materials that can store more lithium in both positive and negative electrodes. These advancements may also help reduce the dependency on scarce and critical raw materials.

In addition to cell chemistry, a battery’s longevity is influenced by its charge voltage. Consumer battery packs typically have a charging threshold of 4.20V/cell to maximize capacity and runtime. Industry and aerospace applications can utilize lower charge voltages, but this increases risk. The best practice for storing a lithium battery is to keep it at around 50% of its full charge capacity when not in use.

High Rechargeability

Lithium ion batteries are rechargeable, making them an excellent energy storage solution. This is largely due to their high power density, which can provide a significant amount of stored energy. However, it is important to understand the safety implications of using lithium ion batteries.

A key factor in battery safety is to ensure that the charging and discharging current does not exceed a set limit. This is generally achieved by the use of a Battery Management System (BMS). The BMS interrupts the charge/discharge cycle when it detects a potentially dangerous condition, such as overvoltage or undervoltage. It also protects against a short circuit, which could cause an explosion.

Batteries are considered fully charged when the charging current drops to a low value. This is referred to as the “top off” charge. It is recommended to keep the top off charge current low, as high Li-ion battery pack currents can lead to a buildup of the self-discharge (SEI) layer and reduce the battery’s life.

It is also essential that a battery is never allowed to discharge below its minimum voltage, which is typically between 2.4 V and 3.0 V per cell in series. This will prevent damage caused by internal chemical reactions and extend the battery’s lifespan. In addition, it is a good idea to store a battery at low temperature to avoid permanent capacity loss over long periods of time.

Lightweight

Whether powering your portable electronics or propelling your electric vehicle, lithium-ion batteries provide the energy to make things work. Their ability to be much smaller and lighter while delivering the same or even greater power than nickel-cadmium batteries has enabled such innovations as super-slim mobile phones and electric cars with a practical range.

Lithium-ion batteries are constructed of individual lithium cells containing a non-aqueous liquid electrolyte and separated by porous separators. The ions move between the cathode and anode through channels in the crystalline structure of the anode material, called spinel, which is able to transport lithium ions without forming dendrites. This allows the battery to have a higher energy density and cycle life than lithium polymer.

A battery’s safety features are built into the cell, with protection circuits limiting the peak voltage during charge and preventing the cell from dropping too low on discharge. They also monitor the temperature of the battery, preventing overheating that can cause fires or explosions.

Lithium batteries must be shipped as Class 9 miscellaneous hazardous materials, and the packaging must contain warning labels and documentation. They should be stored cool, and ideally in a refrigerator, as heat speeds up their aging. They need to be recharged every 30 days or so in order to maintain their full capacity and keep the electronic “fuel gauge” working properly.