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Resettable fuse Protection of lithium batteries normal work

文章出处:Resettable fuse factory Author:Yaxun Electronics Popularity: Time:2017-02-08 23:21 【Big Middle Small
Resettable fuse Protection of lithium batteries normal work
 Lithium-ion batteries, also known as polymer batteries,Compared with NiMH or NiCd batteries,With a unit volume of electrical energy capacity,Current density, high conversion efficiency,Can be fast charging, small size,Light weight and other unique advantages.Not only is widely used in a variety of portable devices, mobile devices.But also in medical devices, industry, agriculture, national defense,Transport and other fields have gradually been able to promote.

Lithium batteries mainly consists of two parts:A pair of electrodes and an electrolyte present therebetween.There are many kinds of electrode materials,Can be lithium, it can be graphite,Even nanowires,But without exception, must rely on this chemical composition of lithium.This is a reactive metal,So easy to synthesize with other elements.Pure lithium activity is extremely high,Will also spontaneous combustion in the air,So most of the batteries are more secure lithium cobalt oxide.
            But the practical application of lithium-ion battery is very fragile,For overcharge,Over discharge,High temperature environment is very sensitive.When charging to the battery voltage is too high,Will increase the battery leakage, smoke, burning, the risk of burst,And the process of such risk is often quite violent.
    Between the two electrodes is the electrolyte,Usually a liquid organic solvent,So that electrons can flow therein.When the lithium battery is charged,Lithium cobalt oxide molecules can capture electrons,And then release the electrons during use of the battery,Thereby supporting the mobile phone operation.
     Overcharge may be caused by charging out of control,Electrode error or incorrect charger used;Lithium-ion battery charge and discharge current is too large or external short-circuit,Internal heat may damage the battery or burn other components,Seriously shortening the cycle life of the battery;The same lithium-ion battery in the high-temperature environment or work load,High-current lithium-ion battery to produce high-temperature,Lithium-ion batteries will also increase the battery leakage, smoke, burning, the risk of burst.
   If the battery discharge is excessive,The internal chemical substances will break down,An excessive amount of lithium oxide is generated,Thereby burning,And generate more lithium oxide, so repeated.Chemists call it "thermal runaway"Ordinary people see is the fire,
 So the lithium-ion battery must design a dedicated battery management circuit,All of the lithium-ion battery management circuit contains overcharge,Over-discharge termination control function,Without battery over-current protection,Battery over-temperature protection,Battery short-circuit protection design,So the task is to protect the circuit for the battery may be a variety of failures,The battery charge and discharge parameters of the state to monitor,To ensure battery life and performance,So that the battery and external equipment from damage
  Due to possible fire,So lithium batteries must be tightly controlled.Battery manufacturers to charge the controller to manage the current,Thereby achieving this purpose.In fact,Each battery has a built-in small computer to prevent overcharging / discharging.This component also controls the current that flows into the battery during charging,In the upcoming full of slow down the current,Avoid overcharging.Now the battery manufacturers in the battery circuit by adding PTC self-recovery fuse,Play overcurrent / overheating protection role,So that the battery becomes safe.
Lithium battery PTC protection circuit