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Lithium-Ion Battery Discharge Curve – Introduction and Efficiency
A type of rechargeable battery, the popularity of Lithium-Ion battery is growing by the day. This type of battery is used to run so many things, including portable electronics and electric vehicles. The topic of this battery was first insinuated by M. Stanley Whittingham, a British chemist. He made a startling discovery by managing to store lithium ions within the folds of a disulfide material. A prototype Li-Ion battery was first developed in 1985.
The three primary parts of this kind of battery are the positive electrode, negative electrode, and electrolyte. The positive electrode tends to be a metal oxide. Meanwhile, the negative electrode is created from carbon. Based on the direction of the current flow, the two electrodes' electrochemical capacities alter between anode and cathode. Finally, a lithium solute in an organic solvent serves as the electrolyte. Read on to learn more about how these batteries work.
Asymmetry of Discharge/Charge Curves of Lithium-Ion Battery?
As mentioned earlier, Lithium-Ion batteries have a lot of uses. Some of the devices which employ these batteries include mobile phones, laptops, tablets, camcorders, e-cigarettes, hedge trimmers, drills, electric cars, etc.
One of the most exciting aspects of Lithium-ion batteries is the asymmetry of discharge/charge curves. NCA-based or Nickel Cobalt Aluminium-based lithium-ion batteries showcase a well-defined asymmetry in discharge/charge performance towards high bulk stoichiometry.?Experts?have successfully derived the same discharge/charge behavior via electrochemical relationships such as the Nernst equation and the Butler-Volmer equation.
The experts had employed a two-steps mechanism during their experiment. First, they conducted lithium-ion adsorption onto the active material surface from the electrolyte under electron transfer. Next, they went on to inject surface-adsorbed lithium ions into the bulk material.
Is it a Good Idea to Fully Discharge a Lithium-Ion Battery?
According to experts, it is not a good idea to discharge a Lithium-Ion battery. It is as dangerous as charging it too much. Here is what happens when you remove a Li-Ion battery below its safe, low voltage, as determined by battery manufacturers.
The copper contained in the anode copper current collector may disintegrate into the electrolyte. During charging by chemical reduction, the copper atoms may stick to the anode and result in dendrites. Consequently, these dendrites may lead to a short circuit.
When you discharge a lithium-ion battery below 2.5 volts per cell, it leads to the opening of a safety circuit inside the battery. The battery will appear to be dead, and the original charger will be rendered worthless.
If you leave a lithium-ion battery discharged for too long, it may stop working. Thus, experts recommend storing it in a "half-charged" state to prevent both overcharged and discharged. It is because lithium-ion batteries do not possess charge memory like NiCad batteries to do. Hence, deep discharge cycles aren't required. However, please note that chemistry, performance, cost, and safety may vary from one lithium-ion battery to another. The battery cycle of this type of battery can also be affected by different factors, including temperature, discharge current, charge current, etc.
Please note that batteries do not undergo full-on charging or discharging in devices such as smartphones, laptops, and electronic cars. Thus, determining battery life via complete discharge cycles may not derive the perfect result.
Here are some tips that can help extend the battery life of Lithium-ion batteries:
The batteries should be kept at room temperature. Thus, the ideal temperature is 20-25 degrees Celsius. It is not a good idea to expose your battery to high-temperature surroundings while it is charging.
If and when you decide to get a Lithium-ion battery, make sure to get one that has been manufactured recently. It is because batteries tend to deteriorate fast.
According to experts, partial discharge is the way to go. However, users should also allow complete discharge after 30 charges. It is because regular partial discharge can lead to the condition of digital memory.
How Fast Can You Discharge a Lithium-Ion Battery?
If appropriately used, the Lithium-Ion battery can run for a period of two to three years. It means over 300 to 500 charge cycles. Here is how one charge cycle works. It is the period of use from charged to fully discharged and back to full charge again.
With time, rechargeable Li-ion batteries lose the capacity to hold a charge. This loss cannot be reversed, and it will also affect the device it is supposed to charge. When not in use, these batteries tend to self-discharge over time.
However, experts often recommend "partial discharge" and even an "almost full discharge." As lithium-ion batteries do not have any charge memory like other batteries, a complete, deep discharge is not required. After 30 consecutive charges, one may go through with an almost full discharge. It is to ward off digital memory, which is a condition created due to too many partial discharges.
If you wish to store your Li-ion battery for an extended period, experts recommend discharging it to about 40% before stacking it away. It is because oxidation of the lithium-ion is at its highest rate when you leave it fully charged.?
Please steer clear of over-discharging as it can lead to a short circuit, and remember to keep your battery away from elevated temperatures.
To Sum Up
There are specific safety measures that people need to keep in mind while using these batteries. If the flammable electrolyte gets damaged, it can be dangerous. Short circuits may also happen. Thus, these batteries may incur fire hazards. If the battery gets damaged or overloaded, it may also trigger a battery explosion.
As the popularity of li-ion batteries increases, so does the generation of waste. These batteries made way for?250,000 tonnes?of unprocessed waste in 2017. Accumulation of these battery wastes can have severe repercussions on the environment. Thus, efforts need to be made towards the proper recycling of waste.