Lithium-ion batteries or Li-on batteries (for short LIB) can store electrical energy in the form of chemical energy. The rechargeable and non-rechargeable LIB batteries are commercially available in the market. Non-rechargeable LIB batteries (also called primary batteries) have long shelf lives and low self-discharge rates and are commonly manufactured as small button batteries for devices such as portable electronics. user movements, wristwatches and headphones. Rechargeable LIB batteries (also called secondary batteries) are used in all consumer electronics and are now entering new markets such as electric vehicles and energy storage. large scale. The LIB rechargeable battery can be used to provide power system services such as primary frequency regulation, voltage regulation and load shifting, as well as to store energy in individual homes. In the section below, we focus only on the rechargeable LIB battery.
A LIB battery consists of two hollow electrodes separated by a pore membrane. A liquid electrolyte fills the voids in the electrodes and diaphragm. Lithium salts (eg LiPF6) are dissolved in the electrolyte to produce Li+ and PF6- ions. These ions can move from one electrode to another through holes in the electrode and diaphragm. Materials in both the negative and positive electrodes can react with Li+ ions. The negative electrode in a LIB battery is usually made of carbon and the positive electrode is made of Lithium metal oxide. Electrons cannot move through the electrolyte, and the physically separated membrane between the electrodes prevents electrons from moving from the negative electrode to the positive electrode and causing a short circuit in the battery. The components in the LIB battery are depicted in the figure below.
When the two electrodes are connected via an external circuit, the battery begins to discharge. During discharge, electrons flow through an external circuit to go from the negative electrode to the positive electrode. At the same time, Li+ ions will leave the negative electrode and move to the positive electrode through the electrolyte, where these ions will react with the positive electrode.
This process is completely natural since the two electrodes are made of different materials. To put it simply, the positive electrode "prefers" electrons and Li+ ions to the negative electrode.Energy is released when one Li+ ion and one electron leave the negative electrode and reach the electrode. The anode is calculated as the voltage of the battery multiplied by the charge of the electron.In other words, the voltage of the battery – also known as the electromotive force (EMF) – is the energy released from each electron during the process. discharge.
The EMF is typically around 3-4 Volts and depends on the chemistry of the LIB battery, the temperature and the state of charge (SOC for short – see information below). For example, when a light bulb is added to an external circuit, the voltage drops mainly through that bulb and so the energy released in the LIB battery is dissipated at the bulb. If the bulb is replaced with a voltage source (e.g. power supply) the process taking place in the battery can be reversed and electricity can then be stored in the battery.
The process of discharge and charge is depicted in the figure below. The battery releases its full power when almost all the Lithium leaves the negative electrode and reacts with the positive electrode. If the battery discharges more than this, the chemistry in the electrode becomes unstable and begins to degrade. When the LIB battery releases its full power, the EMF is low compared to when the battery is fully charged. The chemistry in each LIB battery has a safe voltage range for EMF and the dead points of this voltage range typically correspond to 0% and 100% state of charge (SOC). Discharge capacity is measured in amperes times hours, Ah, and depends on the type and mass of material in the electrodes.
source https://blognewszin.blogspot.com/2021/11/what-is-lithium-ion-battery.html
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