Lithium-ion batteries are used for high-powered devices and applications as they provide steady power in demand. They are found in phones, laptops, electric vehicles, and other devices. While lithium-ion batteries provide optimal battery power, optimizing the cell life ensures that the batteries can last for many years.
Lithium-ion technology continues to evolve to provide low self-discharge and high energy density greater than 0.46Mj/kg. While theoretically, a lithium-ion battery could last for 5 years or more with essentially 2,000-3,000 charging cycles, most manufacturers lower this range to roughly 300 to 500 charging cycles, or 2-3 years, due to the possible application for the battery pulling more power from the battery.
Other factors that impact a lithium-ion's lifespan include how the battery is taken care of and how it is stored. There are several ways to extend its use and prolong lithium-ion battery life.
Provide Ideal Battery Storage Conditions
Most customers may not plan to use the lithium-ion battery pack in the device immediately. Instead, the battery pack will be placed into the device when a product ordered becomes placed or installed into the device as the device will be packaged for the warehouse. In these cases, proper storage conditions greatly impact the battery life. If the battery is improperly stored, it may not provide its fullest capable capacity when placed into service.
Lithium-ion battery cells stored in climate-controlled room.
Lithium-ion batteries are greatly influenced by room temperatures. If stored in an excessively hot room, the battery can degrade faster than normal. Store the battery packs in a cool room of about 59° Fahrenheit, and they should be stored at their partial charge of about 40% or 50%.
Also, keep track of the humidity in the room. Moisture will reduce the cell's lifespan and performance. The ideal room environment should be a cool and dry location with ventilation. Never store the battery packs near sunlight as the heat from the sun's rays can raise the battery's temperatures.
Monitor Self-Discharge Rate
If you plan to have lithium-ion batteries in storage for long periods of time, the good news is that the self-discharge rate for lithium-ion batteries is low and steady. The battery will first go through an initial 5% discharge within a 24-hour period and then discharge at a rate of 1% to 2% each month. If the lithium-ion battery has a safety protection circuit, the monthly self-discharge rate increases up to 3% each month.
However, lithium-ion batteries should never be completely drained to 0% or go below 20%, roughly lower than its 2.50 volt/cell state. The use of battery management systems (BMS) can help you monitor the battery's state of charge as well as its temperature and other factors. If the battery is reaching low levels, you should charge it before placing the battery back into storage.
Proper Charging/Discharging During Use
Extreme overcharging and deep discharging cycles place high levels of stress on lithium-ion batteries. When it comes to overcharging, tree-like lithium dendrites (whiskers) will form on the negative electrodes. These whiskers can cause serious problems as they are highly explosive to lithium-ion batteries.
To prevent whiskers, a custom battery pack can be designed with a regulator that helps balance the different cell capacities in the battery pack. It can improve the state of charge levels throughout the pack to prevent overcharging of cells that have higher capacities than other cells in the pack. It will prevent the weakest cells from being overcharged as well as stop the cells from discharging when the lowest capacity cells are near the empty level.
To prolong battery life, consider doing partial charges up to 80% state of charge (SoC) instead of a 100% charge. If the lithium battery is going to reach 100% charge, make sure to take the device off power immediately once reaching that level. Also, ensure that you are charging the battery in a room that has a lower temperature. Room temperatures between 50° Fahrenheit to 95° Fahrenheit.
Depending on the device, operation, and available ventilation, the application should operate in temperatures from 32° Fahrenheit to 95° Fahrenheit. Higher temperatures will cause the battery to discharge quickly. If the device is hot and the lithium-ion battery is discharging faster than normal, you may want to adjust the device's operation. For example, a laptop may be extremely hot due to running high-powered applications, such as video games.
Be Careful with Fast Charging
Fast charging and ultra-fast charging allow lithium-ion batteries to reach full capacity in less time. Fast charging can be done with this battery cell chemistry yet should be reserved for lithium-ion batteries designed by manufacturers that can accept such a rapid charge. One of the dangers to fast and ultra-fast charging lies with plating that can occur on the anode of the battery. Also, lithium deposition, dendrite, along the negative electrode can happen at a rapid pace.
If fast charging a lithium-ion battery, which is common in the electric vehicle industry, the battery should be charged at a temperature of about 60° Fahrenheit. This temperature will allow the cell to receive an optimal 10-minute charge of up to 80% SoC. The fast charging should only happen up to the capacity reaching 70%, then the battery should have the charge current lowered for the remaining time. This method is considered step charging. In addition, the cells in the battery pack should be balanced.
Summary
Lithium-ion cell chemistries are highly reactive. They can become unstable if mishandled or improperly charged/discharged. They should be handled with care and not be punctured or damaged. Taking active steps in prolonging the life of the battery ensures that it will last for a long time. Extending lithium battery life helps provide optimal power for applications while also lowering the amount of waste created from damaged or degraded batteries.
Battery manufacturers will offer specific handling, charging, discharging, and storage specifications based on their manufactured product. Speaking with a battery pack manufacturer allows you to learn about the necessary steps in extending the battery's life based on the specific application to ensure the device receives optimal power while in full operation without experiencing a loss in battery capacity.
