Lithium Battery Chargers
Lithium batteries power most of the things we use, from cell phones and laptops to electric cars and cordless power tools. But they aren’t without their risks.
To minimize these risks, FDNY firefighters are trained to handle lithium batteries safely when responding to fires. But what are lithium batteries actually made of?
Electrochemical Process
The battery’s electrochemical process involves the passage of current between lithium battery electrodes. As current flows, it causes magnetic effects and a series of chemical changes that occur at or near each electrode (see BU-104b: Battery Building Blocks). At the negative electrode, known as the cathode, this may involve reduction of water to produce hydrogen and a basic substance; at the positive electrode, called the anode, it may be oxidation of water to produce oxygen and an acidic substance.
To avoid this, the electrodes undergo a drying process that reduces any humidity. This is important for batteries because moisture can cause degradation and capacity loss in the anode. The dry electrodes are then transported to a climatically controlled environment.
Once in the dry cell, a partial vacuum is created to help ensure that the anode and cathode coatings are fully distributed throughout the electrode. A pre-determined quantity of electrolyte is dispensed into the cell and is weighed before and after filling to ensure quality. HF, a byproduct of the chemical decomposition of the anode, must be kept at very low ppb levels to prevent any safety hazards.
One potential way to improve the electrochemical performance of the electrodes is to replace the nonpolar NMP solvent with water. However, this presents a challenge because water is a polar solvent and thus behaves very differently from NMP, making the active materials agglomerate and metal current collector surfaces hydrophobic.
Lithium Ion Battery Cells
Lithium ion batteries are currently the most popular battery technology. They have the highest energy density and can be recharged a number of times over a long lifetime. However, they are prone to a safety issue known as thermal runaway (TR), caused by the exothermic chemical decomposition of a cell’s components. The risk is lessened by selecting a safe cathode chemistry, such as lithium iron phosphate (LiFePO4).
The internal structure of a lithium ion battery consists of a positive electrode, the cathode, and an electrolyte separator. The cathode can be made from a variety of materials, including lithium cobalt oxide and lithium manganese oxide. The electrolyte is a fluid consisting of a solvent, additives, and salts that functions as the conduit for lithium ions to move between the cathode and anode during charging.
It is critical to ensure that the electrolyte does not reach high temperatures during charging. Failure to do so could cause the oxidation of lithium in the anode and spontaneous transfer of metallic lithium to the container metal, which causes embrittlement. This is a significant factor in the design and testing of lithium ion battery packs, and a major function of the battery management system.
Another important aspect of a lithium battery cell is its SEI film, which acts as a protective barrier against overheating. This layer of material, which resembles a plastic film, prevents the lithium ions from passing through the separator and into the cathode when the battery is overheated.
Lithium Ion Battery Chargers
Lithium ion battery chargers are essential for charging your batteries and getting the best performance from them. We carry a large selection of safe lithium ion chargers that can handle a wide range of different chemistry types.
In most cases a li-ion battery will require constant current, constant voltage (CCCV) charging. This is because the ions have to transport across various interfaces within the cell. They have to move from the bulk of the cathode material, through the separator to the electrolyte/anode interface and then diffuse back into the anode. All of this is governed by the mobility of the ions and is influenced by temperature and ionic concentration.
This means that the charger circuitry needs to be able to monitor these variables and control charge rates. It also needs to ensure that the ions don’t reach a maximum voltage during charging. This is because overcharging can damage the battery and cause it to fail catastrophically. The ions would convert the electrical energy to thermal energy and then explode.
One of the benefits of lithium ion batteries is that they can be charged relatively quickly. This is because they don’t need to be fully saturated like lead acid. They can be charged to about 80% of capacity in a matter of minutes. This makes them ideal for applications that require fast charging times.
Lithium Ion Battery Disposal
Lithium ion batteries require very little maintenance, which makes them popular for consumer electronics like wireless headphones and cell phones. However, lithium batteries need to be properly disposed of when they reach the end of their life.
When lithium ion batteries are improperly discarded, they can cause fires in garbage trucks or recycling facilities. For example, a Brooklyn recycling center was destroyed in 2021 when a lithium battery was mistakenly thrown into a regular trash container.
To recycle lithium batteries, qualified technicians must first dismantle them into modules. These professionals are trained high-voltage specialists who use insulated tools to prevent electrocution or short-circuiting, which can generate noxious byproduct gasses.
After dismantling lithium batteries, they can be melted down or dissolved in acid. This produces a black mass with a texture that can range from powder lithium battery to goo, from which chemical elements and simple compounds can be salvaged. These recycled products can then be used to make cathodes in new lithium ion batteries.
It’s important to separate rechargeable lithium batteries from regular AA alkaline batteries when discarding them, because they look similar. Also, tape over the battery terminals to protect against accidental short circuits. Finally, store lithium batteries in a container with a tight-fitting lid. For safety, the lid should be labelled “lithium batteries.” Call2Recycle program procedures follow strict international and US hazardous waste laws to reduce the risk of fire hazards in landfills and incinerators.
