BATTERY TECHNOLOGY

A lithium-ion battery or Li-ion battery (abbreviated as LIB) is a type of rechargeable battery in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging. Li-ion batteries use an intercalated lithium compound as one electrode material, compared to the metallic lithium used in a non-rechargeable lithium battery. The electrolyte, which allows for ionic movement, and the two electrodes are the constituent components of a lithium-ion battery cell.

Lithium-ion batteries are common in home electronics. They are one of the most popular types of rechargeable batteries for portable electronics, with a high energy density, tiny memory effect and low self-discharge. LIBs are also growing in popularity for military, battery electric vehicle and aerospace applications.

Lithium-ion batteries can pose unique safety hazards since they contain a flammable electrolyte and may be kept pressurized. A battery cell charged too quickly could cause a short circuit, leading to explosions and fires. Because of these risks, testing standards are more stringent than those for acid-electrolyte batteries, requiring both a broader range of test conditions and additional battery-specific tests. There have been battery-related recalls by some companies, including the 2016 Samsung Galaxy Note 7 recall for battery fires.

Research areas for lithium-ion batteries include life extension, energy density, safety, cost reduction, and charging speed, among others. Research has also been under way for aqueous lithium-ion batteries, which have demonstrated fewer potential safety hazards due to their use of liquid electrolytes.

Most modern mobile devices use lithium ion (sometimes called Li-ion) batteries, which consist of two main parts: a pair of electrodes and the electrolyte between them. The materials that these electrodes are made of varies (they can be lithium, graphite, or even nanowires), but they all rely on the chemistry of lithium. It's a reactive metal, which means that it has a tendency to combine with other elements. Pure lithium is so reactive, it can catch fire in the air, so most batteries use a safer form called lithium cobalt oxide. Between the two electrodes is the electrolyte, which is usually a liquid organic solvent that allows electrons to flow between them. When a lithium ion battery is charged, the lithium cobalt oxide molecules capture and hold electrons, which they then release when the battery is in use, such as when it is running your cell phone.

Battery capacity

The capacity of a battery is measured in milliampere-hours (or mAh), which indicates how much energy the battery can deliver over time. For instance, if a battery has a rating of 1000 mAh, it could deliver 1000 milliamps of power for 1 hour. If your device uses 500 milliamps of power, the battery should last about 2 hours.

The battery life of a device is a bit more complicated than that, though, as the amount of power a device uses changes depending on what it is doing. If the device's screen is on, the radio is transmitting, and the processor is working hard, it will use more energy than if the screen is off and the radio and processor are idle.

Controlling the flow of power

Battery makers accomplish that by building in a charge controller that manages the flow of electricity. In effect, every battery has a small computer inside it that prevents it from being discharged too fast, or to a dangerously low level. This component also regulates the flow of power into the battery during charging, slowing the flow of power as the battery gets close to being fully charged to prevent overcharging.

The future of power

Battery technology is always improving, with labs around the world looking for new battery technologies to replace lithium as well as new approaches to building lithium ion batteries. Among the new technologies, a lot of work has gone into supercapacitors, in which the battery stores energy electrically and then releases it, like a flash gun. Supercapacitors could allow for much quicker charging, as little chemical change is involved, but current supercapacitors can deliver power only in short bursts, which is the opposite of what most mobile devices need. Fuel cells that use hydrogen to generate electricity are also coming soon. The Nectar fuel-cell system, announced at the CES trade show in January, uses a $10 cartridge to power a cell phone for up to two weeks. However, fuel cells are not yet small enough to fit inside a phone—the Nectar system charges the existing lithium ion battery and doesn't replace it.

Safety

If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture.^[174] In extreme cases this can lead to leakage, explosion or fire. To reduce these risks, many lithium-ion cells (and battery packs) contain fail-safe circuitry that disconnects the battery when its voltage is outside the safe range of 3–4.2 V per cell. or when overcharged or discharged. Lithium battery packs, whether constructed by a vendor or the end-user, without effective battery management circuits are susceptible to these issues. Poorly designed or implemented battery management circuits also may cause problems; it is difficult to be certain that any particular battery management circuitry is properly implemented. Lithium-ion cells are susceptible to damage outside the allowed voltage range that is typically 2.5 to 3.65 V for most LFP cells. Exceeding this voltage range, even by small voltages (millivolts) results in premature aging of the cells and, furthermore, results in safety risks due to the reactive components in the cells. When stored for long periods the small current draw of the protection circuitry may drain the battery below its shutoff voltage; normal chargers may then be useless since the BMS may retain a record of this battery (or charger) 'failure'. Many types of lithium-ion cells cannot be charged safely below 0 °C.

Other safety features are required in each cell:

·         Shut-down separator (for overheating)

·         Tear-away tab (for internal pressure relief)

·         Vent (pressure relief in case of severe outgassing)

·         Thermal interrupt (overcurrent/overcharging/environmental exposure)

These features are required because the negative electrode produces heat during use, while the positive electrode may produce oxygen. However, these additional devices occupy space inside the cells, add points of failure, and may irreversibly disable the cell when activated. Further, these features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device and a back-up pressure valve. Contaminants inside the cells can defeat these safety devices. Also, these features cannot be applied to all kinds of cells, e.g. prismatic high current cells cannot be equipped with a vent or thermal interrupt. High current cells must not produce excessive heat or oxygen, lest there be a failure, possibly violent. Instead, they must be equipped with internal thermal fuses which act before the anode and cathode reach their thermal limits.

There are four basic types of rechargeable battery used in mobile phones:

1.   Nickel Cadmium (NiCd) Batteries
Nickel Cadmium cell phone batteries are based on old technology.  The chemicals used in NiCd batteries are not environmentally friendly, and the disposal of cadmium-rich waste is an increasing problem. They are the cheapest variety of phone batteries. Their affordablility helps to bring down the overall cost of mobile phones.

2.   Nickel Metal Hydride (NiMH) Batteries
Nickel Metal Hydride (NiMH) batteries claim to be superior to NiCd because they don’t contain cadmium. The cell phone batteries are made from non-toxic materials and are environmentally friendly. They also deliver a higher capacity in relation to their size and weight.

3.   Lithium Ion (Li-Ion) Batteries
This is the current and most popular technology for cell phone batteries. The only real drawback of Lithium Ion cell phone batteries is that they are expensive. As such, they tend to be supplied with only top-of-the-line phones. Lithium Ion batteries are slightly lighter than NiMH batteries, but they also have a longer lifetime. A Lithium Ion battery may be damaged by extensive overcharging (continuously on a cell phone charger for more than 24 hours).

4.   Lithium Polymer (Li-Poly) Batteries
Li-Poly Batteries are the newest and most advanced technology for cell phone batteries. Ultra-lightweight, they do not suffer from memory effect and will deliver up to 40% more battery capacity than a Nickel Metal Hydride (NiMH) of the same size.

Conclusion

Li-ion batteries and cells or li-ion batteries and cells are now in widespread use. They have taken a position of dominance in the rechargeable battery market and as a result many mobile phones, laptop computers and cameras, etc use them. Although there are many new battery developments taking place, lithium ion batteries, li-ion batteries will remain one of the main types of battery for many years to come. Lithium Ion and Lithium Ion Polymer batteries are a great power source for projects but they require care during use and charging. They can be easy to damage or misuse and can hurt you or your property! All the batteries are sell pass testing and certification but you should still be careful with them.

BY:- TARLOCHAN BHIKHA