Lithium Ion Battery Protection

Lithium-ion batteries are a key component of powering the electronics and electric vehicles that are rapidly growing in popularity. Their higher energy density allows for smaller, lighter batteries with the same capacity.

They are also safer than previous battery types. But these batteries have their drawbacks, including the use of an etching solvent (NMP) that has been linked to a number of fire incidents in electronic cigarettes and hoverboards.

High Energy Density

Lithium-ion batteries offer a much higher energy density than other practical secondary batteries (which are usually made of lithium or cobalt oxide). Li-ion battery energy densities can be measured in watt-hour per kilogram (Wh/kg), which is equivalent to the number of electrical joules stored in the battery when fully charged.

The most important factor in a battery’s energy density is its anode material. The most common anode for lithium ion batteries is graphite. The main goal of research is to improve the anode material, while maintaining its nonflammability and mechanical strength.

The demand for portable electronic devices with long stand-by times and electric vehicles with a long driving range have stimulated the development of high rate and quick-charging Li-ion batteries. Such batteries require electrode materials that can be quickly charged at a high current without degrading their active material or generating severe heat release. Improving the intrinsic electronic conductivity of the electrode material or introducing conducting networks into it facilitates faster electron transport. The result is a fast charging battery with high energy density.

Long Lifespan

Lithium-ion batteries are designed to last a long time, but the expected lifespan of lithium ion batteries is dependent on a number of factors. These include cycling, elevated temperatures and ageing.

The battery operates by allowing lithium ions to move between the anode and cathode through the electrolyte. This movement allows the battery to store energy in its Lithium Ion Battery cells. The anode is usually made from graphite powder, the purity, particle size and uniformity of which are important to the battery’s aging behaviour and capacity. The cathode is often made from LiCoO2, although other materials like nickel iron, are also being explored.

Unlike lead-acid batteries, lithium ion batteries do not suffer from sulfation, which reduces battery capacity over time. However, a battery’s longevity can still be significantly reduced by deep discharging, overcharging, temperature and storage conditions. Battery management is vital to maximize battery life. Choosing the right charger, regular partial charging and keeping the battery at a low State of Charge prolongs its life. Contact the experts at Northeast Battery to learn more about how you can best manage your lithium ion battery.

Fast Charging

A battery is able to charge quickly when it has a low internal resistance. However, it must be matched with an equally fast charger to take advantage of this property. A battery that is charged and discharged too slowly can cause damage to the internal components.

Lithium ion batteries are capable of ultra-fast charging because they have a thinner anode and lower porosity than lead-acid battery electrodes. This allows the lithium ions to pass through the electrolyte and electrodes more quickly. However, the rate at which a battery is charged can still be limited by physical barriers.

NREL’s XCEL team is working to improve the speed of Li-ion transport with new electrolytes, advanced electrodes, adaptive electrochemical protocols, and optimal thermal controls. Their goal is a cell that can achieve 80% charge in 15 minutes for 200 cycles and retains 3 times more capacity than existing pouch cells.

One of the main obstacles to rapid charging is the formation of a dense and conductive SEI on the graphite anode. Researchers have found that using linear carbonate-based electrolytes with boron compounds can decrease the activation energy for desolvation of the solvent sheath on the SEI and allow it to pass through more quickly.

Reliability

Although lithium batteries are more resilient than some other rechargeable battery technologies, they still require a system to protect them from overcharging and excessively discharging. They also need to be kept within a safe current range to avoid fire hazards.

Lithium-ion battery cells are grouped in groups to form batteries, which are then assembled into large batteries for use in electric drive products. The reliability of the entire battery pack depends on the degradation rate and dependency of individual cells. Previous research has evaluated the reliability of complex grouped structures by using a series-parallel reliability equation without considering the internal dependency among cells, which may result in a greatly underestimated reliability evaluation of battery packs.

To quantitatively measure the degree of dependency in cell degradation processes, a Copula function was used to connect the degradation data of unit cells. Then the dependencies were quantified and established to help establish a reliable model that could accurately depict the reliability of the lithium-ion battery packs with various structures. This model can provide guidance for scheme optimization, adjustment, and the reliability evaluation of battery packs in the reliability design stage of electric drive products.

Safety

As the technology advances, lithium ion batteries are being used in more and more hardware from e-scooters to smartphones and even 24V Lithium Iron Phosphate Battery home solar battery systems. However, if damaged or mistreated, these powerhouses can catch fire and explode.

This is a significant safety risk as the cell’s electrolyte contains a flammable organic solvent that can cause fires or explosions. This is why the battery must be kept away from combustible materials, and it must be kept cool.

The battery’s design includes a separator that prevents the cathode and anode from touching each other. The separator is designed to prevent thermal runaway, which occurs when the battery temperature rapidly increases and leads to a fire or explosion.

The separator is made of a porous polymer material that melts at a specific temperature, shutting down the battery. It also features internal fuses and current interrupt devices that disconnect the terminal internally when a battery is overcharged or overheated. These are just a few of the many engineering features that make lithium ion batteries safe to use. But it’s always best to keep an eye out for any signs of damage or mishandling, such as a strong odor or excessive heat.