Lifepo4 Battery 14500

Polarization of 14500 lithium ion rechargeable battery
In chemical 14500 lithium ion rechargeable battery, the direct conversion of chemical energy into electrical energy is the result of spontaneous chemical reactions such as oxidation and reduction inside the battery. This reaction is carried out on two electrodes. The negative electrode active material is composed of a reducing agent having a relatively low potential and being stable in the electrolyte, such as an active metal such as zinc, cadmium or lead, and hydrogen or a hydrocarbon. The positive electrode active material is composed of an oxidizing agent having a positive potential and being stable in the electrolyte, such as metal oxides such as manganese dioxide, lead dioxide, and nickel oxide, oxygen or air, halogens and salts thereof, oxyacids and salts thereof, and the like.  The electrolyte is a material having good ionic conductivity, such as an aqueous solution of an acid, a base, a salt, an organic or inorganic nonaqueous solution, a molten salt or a solid electrolyte. When the external circuit is disconnected, there is a potential difference, that is open-circuit voltage, between the two poles, but there is no current, and the chemical energy stored in the battery is not converted into electric energy. When the external circuit is on, a current flows through the external circuit under the action of the potential difference between the two electrodes.
At the same time, inside the 14500 lithium ion rechargeable battery, due to the absence of free electrons in the electrolyte, the transfer of charge is accompanied by oxidation or reduction reaction of the interface between the bipolar active material and the electrolyte, and migration of the reactants and reaction products. The transfer of charge in the electrolyte is also accomplished by the migration of ions. Therefore, the normal charge transfer and mass transfer process inside the 14500 lithium ion rechargeable battery is a necessary condition for ensuring the normal output of electric energy. When charging, the direction of the internal power transmission and mass transfer process of the battery is exactly opposite to the discharge and the electrode reaction must be reversible to ensure the normal mass transfer and transmission process in the opposite direction. Therefore, the reversible electrode reaction is a necessary condition for constituting a battery. When the battery has current through, the phenomenon that the potential deviates from the equilibrium potential is called electrode polarization. The overpotential is the difference between the actual potential and the equilibrium potential and is used to measure the degree of polarization. Battery polarization is present in common batteries such as lead-acid batteries, lithium batteries, and nickel-metal hydride batteries.
The difference in electrode potential before and after energization is called the potential difference. The equilibrium electrode potential is an electrode potential in a relatively stationary state in the absence of current flow. The polarization of the 14500 lithium ion rechargeable battery is due to the flow of current, and the actual electrode potential deviates from the equilibrium electrode potential after breaking the static state. The electrode polarization generated by the anode current is called anodic polarization; the electrode polarization generated by the cathode current is called cathodic polarization. The greater the current passing through the unit area of the electrode, the more severe the potential from the equilibrium electrode. For example, iron is rusted because there are impurities inside the iron. Iron will act as a negative electrode in the electrolyte solution, and carbon will be used as a positive electrode to accelerate the corrosion of iron.
Polarization can be divided into three types depending on the cause of polarization: electrochemical polarization, concentration polarization, and ohmic polarization.
The three polarizations above are the resistance of the electrochemical reaction. The internal resistance of the 14500 lithium ion rechargeable battery is the sum of the ohmic internal resistance, the electrochemical polarization internal resistance and the concentration polarization internal resistance.


Use and reuse of 14500 rechargeable battery
For batteries,  the process of discharging is using normally. Need to pay attention to the discharge of lithium battery:
First, the discharge current should not be too large. Excessive current causes heat inside the battery, which may cause permanent damage. But you don't have to pay attention to it if it's on the mobile phone.
The larger the battery discharge current, the smaller the discharge capacity and the faster the voltage drop.
Second, you must never over-discharge! Lithium battery internal storage of electrical energy is achieved by electrochemical reversible chemical changes, excessive discharge will cause irreversible reaction of this chemical change, so lithium batteries are most afraid of over-discharge, once the discharge voltage is lower than 2.7V, it may cause the battery to be scrapped. Fortunately, the inside of the mobile phone battery has been installed with a protection circuit, the voltage is not low enough to damage the battery, thus to stop discharging to protect the circuit.
Charge rate
Sometimes there are two representations of rate and magnification. The time rate is the charge and discharge rate expressed by the charge and discharge time, and is numerically equal to the number of hours obtained by dividing the rated capacity (A·h) of the battery by the predetermined charge and discharge current (A). Magnification is another representation of the rate of charge and discharge, the value of which is the reciprocal of the rate of time. The discharge rate of the primary battery is expressed as the time to discharge to the termination voltage via a certain fixed resistance. The discharge rate has a large impact on battery performance.
Storage life refers to the maximum time allowed to store between the time the battery is manufactured and the time it is used. The total term including the storage period and the usage period is called the expiration date of the battery. The life of the storage battery is divided into dry storage life and wet storage life. The cycle life is the maximum number of charge and discharge cycles that the battery can reach under the specified conditions. The system of charge and discharge cycle test must be specified at the specified cycle life, including charge and discharge rate, discharge depth and ambient temperature range.
Self-discharge rate
The rate at which the battery loses its capacity during storage. The capacity lost by self-discharge during unit storage time is expressed as a percentage of the capacity before storage.
There are three types of waste batteries that are widely used in the world: solidified and buried, stored in waste mines, and recycled.
1. Solidified and buried in waste mine
For example, a factory in France extracts nickel and cadmium, and then uses nickel for steelmaking, and cadmium is reused for battery production. The rest of the waste batteries are generally shipped to specialized toxic and hazardous landfills, but this practice is not only too expensive but also wasteful, because there are many useful materials that can be used as raw materials.
2. Recycle and re-use
a. Heat treatment b. "Wet treatment" c.Vacuum heat treatment


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