The Advantages of a Li-Ion Battery Pack

Lithium-ion batteries provide portable power, ranging from cell phones and laptops to electric cars and tools. They also deliver energy to medical equipment and critical infrastructure.

However, these batteries contain cobalt and graphite — both considered critical minerals. When discarded improperly, they can pose a fire or explosion risk.

1. High Energy Density

The high energy density of lithium-ion batteries makes them popular in everything from laptops to electric vehicles and cell phones. Pound for pound, they pack more electrical power into a battery than any other type of rechargeable battery.

The energy density of a Li-ion battery is the amount of electrical energy that can be stored in it, measured in Watt-hours per kilogram. This figure depends on the positive and negative electrode materials used in the battery, their design and the internal chemistry of the electrolyte.

Graphite is the most common negative electrode material in current lithium-ion batteries. This is because it has a low intercalation voltage and excellent performance. However, newer cathode materials like lithium iron phosphate and nickel-cobalt-manganese are offering greater storage capacity than graphite.

In fact, the energy density of a lithium-ion battery is so high that it allows most of today’s mobile phones to use one single cell instead of three 1.2-volt cells connected in series as they would need in a nickel-cadmium battery. In order to ensure safe operation, all lithium-ion battery packs must contain a protection circuit that limits the peak cell voltage during charge and prevents the cell from dropping too low on discharge.

2. Low Self-Discharge Rate

Li-ion batteries use anodes and cathodes made of different materials, but the most popular combination is lithium cobalt oxide (cathode) and graphite (anode). They also use a liquid or gel electrolyte. The main advantage of this type of battery is its energy density, which is two to three times that of a nickel-cadmium cell.

Unfortunately, the very same characteristics that make lithium-ion batteries so energetic also cause them to burst into flames occasionally. This happens when the separator sheets that keep the positive and negative electrodes apart become punctured. This causes one of the cells to heat up until it vents the organic solvent used as an electrolyte, which can then ignite and burn.

The good news is that this is a rare occurrence. The bad news is that when it does happen, the results are devastating. It’s important to ensure that your battery packs are free from internal short circuits by identifying cells Li-ion battery pack with high levels of self-discharge. Traditional methods involve monitoring cell open circuit voltage over weeks or months. But Keysight’s new solutions can directly measure a cell’s self-discharge current in just 1-2 hours, a significant reduction in test time.

3. Long Lifespan

A lithium battery pack can last for many charge cycles, but it’s important to check the cycle number on your battery and follow manufacturer recommendations. The number of cycles a battery can go through depends on the lithium chemistry and pack design.

While the chemistry is great, lithium batteries aren’t without their issues. They can burst into flames occasionally, but it’s rare, only two to three packs per million experience the issue. It usually happens when a separator fails and allows the internal voltage to drop. This can occur while the pack is charging, or while the cells are discharging.

To avoid this, battery manufacturers incorporate multiple redundant safety cut-offs. These prevent the battery from dropping below a threshold voltage and protect against overcharging and deep discharges. They also limit the maximum current the pack can deliver to prevent it from running too high a load (e.g. a strobe). It’s also recommended to keep batteries charged at around 50% when not in use, as this reduces the capacity degradation.

4. Lightweight

Lithium-ion batteries are the power behind super-slim mobile devices and electric cars with market-leading range. They’re also key to integrating intermittent renewables into power systems for a greener, more sustainable future.

To make lithium-ion battery cells more affordable, researchers have focused on making them smaller and lighter. In particular, they’ve developed a new electrolyte — called spinel — that tightly controls the movement of lithium ions between the electrodes, allowing them to be packed more closely together.

This enables batteries to have a higher energy density than their nickel-cadmium predecessors while maintaining the same safety features. It has even enabled batteries to be used in aerospace applications like the Boeing 787, where weight is a major cost factor.

If you have a device with a lithium-ion battery, check its packaging or contact the manufacturer for specific handling instructions and recommendations. Batteries with an equivalent lithium content of 1.5 grams or more per cell are considered a Class 9 miscellaneous hazardous material by the USPS and require special markings and shipping documents. They should not be placed in household waste or recycled containers.

5. Fast Charging

Lithium-ion batteries are a mainstay in everything from laptops and cell phones to hybrid and electric cars. They’re everywhere because pound for pound they’re the most energetic rechargeable batteries available. Unlike Li-ion battery pack some other battery technologies, they don’t have a memory, so you can use them as often as you want without worrying about losing capacity.

But they do have a drawback: occasionally they burst into flames. While this is rare — only two to three packs per million have the issue — it’s enough to cause a worldwide recall.

The problem is that the battery’s on-board computer can’t always detect when it’s getting too hot, so it sets a maximum charging rate to prevent an internal short. This limits how fast the pack can charge, which hurts its performance and life span. Now, a team of researchers has developed an algorithm to help the battery manager handle high currents, making it possible to increase charging speed and reduce power loss. Their work is described in a paper published on February 9, 2023 in Nature Energy.