The Basics of a Lithium Battery

Lithium-ion batteries are used for portable electronics and electric vehicles. They are a great way to reduce your environmental impact.

However, batteries can degrade quickly. They only last about two to three years from the date of manufacturing.

Electrolyte

The electrolyte is the current-carrying medium that connects the positive and negative electrodes in a lithium battery. It is made up of a liquid solution that contains cations (positively charged particles) and anions (negatively charged particles). The movement of these ions from the anode to the cathode and back again amounts to a current, and it helps the battery store and release energy.

For batteries, a common electrolyte is a soluble lithium salt in a liquid organic solvent, such as ether or carbonate. This helps to move the ions around in the battery and improve its performance. However, it can also cause a battery to catch fire if it becomes exposed to the air.

As a result, researchers have been looking for ways to design new solid-state electrolytes that can withstand high temperatures and improve battery life. One approach involves combining iron phosphate adsorbents with spinel, a mineral that has an AB2O4 structure that is chemically stable and promotes ion flow within the electrolyte.

But it has been difficult to create these adsorbents using conventional methods. The process can be time consuming and requires expensive equipment.

Researchers have developed a more efficient method that uses the same materials as traditional electrodes. It works by encapsulating the surface of the anode material with a layer that acts like a protective coating and is resistant to corrosion.

The coating, which can be based on graphene encapsulated Si nanoparticles, provides an excellent protection for the anode. It can withstand high voltages and avoids the need for a separate insulating film. Additionally, it has excellent thermal stability and promotes ion flow through the electrolyte, which decreases internal resistance.

Cathode

Cathode materials are used in lithium batteries to help power the electric current that runs through the cell. They are made of a combination of an active material, conductive additive, and binder. The lithium ions that are in the battery travel through the electrolyte, where they are absorbed by the cathode materials.

The cathode material must be high-purity to ensure that lithium ions are free from unwanted impurities. Targray provides a full portfolio of lithium-ion cathode materials including Nickel Cobalt Aluminum (NCA), Core Shell Gradient (CSG), Spinel-based lithium-ion (LMO), and Lithium-cobalt oxide (LCO).

As the primary active component in a lithium-ion battery, the cathode is responsible for the energy and power densities that a battery can provide. Because lithium is a highly reactive element, the higher the level of Li in a cathode, the more energy and power it can provide.

Despite the progress made in lithium-ion battery technology, there are still some challenges to overcome. First, the availability of cobalt is limited due to its dependence on foreign sources, which can heighten costs and impact American manufacturing supply chains.

Second, the existing cathode materials are limiting in their ability to deliver energy and power for the long-term. For example, layered oxides such as LiCoO2 are toxic, costly to produce, have a limited range of potential windows, and lack capacity.

In an effort to address these problems, researchers at Oak Ridge National Laboratory have developed a new way to make high-capacity cathode materials without using cobalt. Instead of stirring the cathode material with a chemical in a reactor, they use metals dissolved in ethanol to form crystals. This new process is safer for the environment and costs less than other techniques.

Anode

The anode is the part of a lithium battery that stores and releases electricity. It also plays a role in determining the battery’s safety performance and operating temperature.

Most lithium batteries use graphite powder as an anode material, a low-cost, porous and lightweight substance that can handle high concentrations of lithium ions. In addition to its performance characteristics, graphite also prevents the growth of dendrites, which are roots-like structures that can grow inside a battery and pierce its separator.

Several companies are developing a variety of new anode materials lithium battery for lithium-ion batteries. They all aim to improve energy density, capacity, voltage, safety and durability while minimizing cost.

Silicon, in particular, has been considered as an anode material because it can store more lithium ions than graphite can. However, as with graphite, the insertion of lithium ions into silicon causes it to swell, which can damage its surface and degrade energy storage.

Researchers are now trying to find a way to protect silicon from swelling. Some are adding coatings to reduce expansion, while others have found a way to use silicon suboxides sprinkled into existing graphite.

Another approach is to create a new anode material that consists of a mixture of silicon, graphite and carbon nanofibers. This has been shown to increase energy density by about 20% over graphite alone, and the company expects to start commercializing this material in lithium-ion button batteries later this year.

Other potential anode materials include a-MoO3, LTO (lithium titanate), and high-performance powdered graphene. All of these have their advantages, but all are also prone to aging and corrosion.

Separator

The separator is the key component in a lithium battery, providing a barrier between the anode and cathode, enabling the exchange of ions from one side to the other. This is achieved through the action of the electrolyte on a permeable surface that forms a catalyst and promotes the movement of ions between the electrodes.

In modern lithium batteries, the separator is made from a thin layer of polymer and is about 2-3 percent of the cell’s weight. The separator is a critical part of the cell’s safety and performance, and therefore it must be designed carefully.

There are a number of different types of polymer separators, and some are specifically designed for battery applications. The most common separator is made from polyethylene, which is a high-melting point material. This allows the separator to shut down at temperatures well below where thermal runaway can occur.

However, while the shutdown temperature of the separator is an important factor in the battery’s safety, it is not a guarantee. Some polymer separators have been known to fail in the field, and some have even caused short circuits inside the battery.

Aside from its safety function, the separator also plays a crucial role in determining cell performance, especially power and energy density. Gravimetric and volumetric cell performance are dependent on the separator’s area weight and thickness, as well as its ionic resistance for the movement of ions from one side to the other.

In order to reduce lithium battery internal resistance and improve the cell’s power performance, some separators are now made ultra-thin. These ultra-thin separators can increase energy and power density by up to 2 %, while reducing the cell’s overall thickness.

Safety

Lithium batteries are a major power source for many kinds of devices, such as cell phones and laptops. They also provide energy for e-scooters, electric bikes and cars.

Safety is an important factor for any battery. Lithium batteries can overheat, catch fire or explode if they are not properly used and stored. To ensure safety when using lithium batteries, it is very important to follow the manufacturer’s instructions on how to use and store them.

When charging lithium batteries, always keep them in a safe place and away from children or pets. Never charge batteries in a fireplace or under a tree where they could fall and break or fall on flammable materials.

In addition, it is vital to never charge lithium batteries at temperatures that are above 105degF (40degC). The higher the storage temperature, the more likely the battery will overheat and burn out.

For lithium battery safety, the N/P ratio of the negative and positive electrodes plays a crucial role. A low N/P ratio reduces the anode potential and increases the risk of lithium plating on the surface of the anode during charging, which is a safety-deteriorating process and can shorten battery life.

A high N/P ratio restrains the potential of lithium plating at the anode and lowers the risk of overcharge, which can increase battery life and decrease the probability of thermal runaway or explosion. However, this can be at the expense of increased oxidation and degradation of the electrolyte solvents.

As a result, improving the safety performance of lithium batteries is a continuous research topic. In particular, key materials, electrode and cell design, as well as mechanical, electrical, and thermal effects during the charging/discharging cycles must be taken into consideration for system level safety performances.