Lithium Ion Battery Safety
Lithium ion batteries are found in many devices including laptops, digital cameras and electric cars. They have a positive and negative electrode with an electrolyte and separator.
During charge and discharge, lithium ions shuttle between the cathode (metallic oxide) and anode (porous carbon). This creates electron flow that produces electricity.
Chargers
Lithium ions flow between the cathode and anode in the battery. When plugged in, the lithium ions pass through an electrolyte (a non-aqueous solution of additives, solvents, and salts) to deliver electrons from the outside circuit to both electrodes. This creates a current that’s similar to breathing, with ions flowing in and out of each side.
The anode material determines voltage and capacity; for example, lithium iron phosphate is a popular choice for home energy storage batteries. The cathode material provides an electric current by absorbing ions from the anode. The cathode is coated with a protective separator and a non-aqueous electrolyte.
As a battery charges, the anode material releases lithium ions to the cathode. The charge rate must be limited for Lithium Ion battery packs, since fast charging rates shorten the expected lifetime. A typical 0.8C charge takes 2-3 hours.
Unlike lead acid, lithium ion batteries don’t require full saturation to be “ready to go.” In fact, it is better to avoid a fully saturated charge because high voltages stress the battery and reduce runtime.
However, the battery does need to be topped off on occasion. This is usually done by BMS-controlled systems that perform a “balancing” process to ensure each cell in the battery bank is at the same state of charge. Alternatively, you can use a simpler method: Simply charge the battery to its rated green electricity voltage and let it drain until it is at Stage 1. Then you can use the battery as normal.
Storage
While lithium-ion batteries aren’t as prone to fires or thermal runaway like lead and alkaline batteries, it’s still crucial for businesses to take all the steps necessary to minimise risk. As lithium batteries are flammable and emit toxic gases, it’s vital that they be stored in the safest possible environment, as well as being separated from other combustible materials. If an incident does occur, it’s also important to have your team know exactly how to respond and evacuate the area until the fire is extinguished.
Correct battery storage helps to keep your batteries operational, boosts their longevity, and increases safety. For the best results, lithium-ion batteries should be stored in a dry area that’s cool, preferably between 20 and 35 degrees Celsius. This will ensure that your batteries aren’t overheating and that the internal components don’t start to corrode.
When storing your batteries, they should be in a metal container with a lid and be kept 3 metres away from combustibles at all times. This will reduce the time it takes for a fire to spread, helping to avoid any potential loss of property or injury to staff and customers.
Safety
Lithium ion batteries are one of the safest battery chemistries available today. Their safety features include a battery management system (BMS) that monitors internal cell voltage and temperature to prevent overcharging, over-discharging, or overheating. Additionally, the lithium in a Lithium Ion Battery is contained in a High voltage 10Kw LiFePO4 battery lithium salt electrolyte and is not pure lithium metal. Pure lithium is highly reactive and reacts with water to form combustible hydrogen gas.
These batteries are designed to power many different types of devices, including smartphones and laptops, electric vehicles, portable chargers, and even residential battery energy storage systems. However, a damaged or improperly used battery can slip into thermal runaway, an uncontrollable self-heating state that can lead to fire.
To minimize the risk of this happening, check battery-powered devices often for warning signs such as swelling, hissing noises or excessive heat. If you see any of these signs, stop using the device and immediately follow your home fire escape plan. If a device does catch fire, use a water-based fire extinguisher to keep the fire from spreading until the battery cools down. Special fire extinguishers that can be used on lithium-ion fires do exist but are not yet widely available for all uses. If a battery is unable to be put out by water, it can reignite hours or even days later.
Performance
Lithium batteries are used to power electronic devices such as smartphones, laptops and tablets, and also electric vehicles (EV). They have a higher energy density than other types of rechargeable battery, so it’s important that they stay in good condition. This is especially true for EV batteries, as their performance directly impacts driving range and the amount of money spent on fuel.
Li-ion batteries are based on intercalation electrodes, where lithium ions are inserted into graphite anodes to store electrical charge. They have a much higher energy density than cells using redox metal cathodes. Graphite is preferred due to its low intercalation voltage, which allows large capacity for small volume.
During charging, the external electrical power source applies an over-voltage to the cell that forces electrons to flow from the positive to the negative electrode. The flow of electrons releases the stored chemical energy in the form of heat. The excess heat is absorbed by the electrolyte, reducing its viscosity and increasing its temperature.
During discharging, the lithium ions migrate from the anode to the cathode. This is a highly reversible process that increases the battery’s cycling capacity. The cycle life of lithium-ion batteries depends on the charging and discharging protocols, operating temperature, and environmental conditions. It has been suggested that every 70mV reduction in peak charge voltage doubles the cycle life, so limiting the maximum discharge current helps prolong battery lifespan and reduce maintenance costs.