LITHIUM ION BATTERIES

The term lithium ion batteries refers to a rechargeable battery where the negative electrode (anode) and positive electrode (cathode) materials serve as a host for the lithium ion (Li+).  Lithium ions move from the anode to the cathode during discharge and are intercalated into (inserted into voids in the crystallographic structure of) the cathode. The ions reverse direction during charging.  Since lithium ions are intercalated into host materials during charge or discharge, there is no free lithium metal within a lithium-ion cell.  In a lithium ion cell, alternating layers of anode and cathode are separated by a porous film (separator). An electrolyte composed of an organic solvent and dissolved lithium salt provides the media for lithium ion transport.  For most commercial lithium ion cells, the voltage range is approximately 3.0 V (discharged, or 0 % state-of-charge, SOC) to 4.2 V (fully charged, or 100% SOC).

Lithium-ion batteries (Li-ion) have several advantages over conventional lead-acid batteries:

  • High energy density: more energy with less weight
  • High charge currents (shortens the charge period)
  • High discharge currents (enabling for example electrical cooking on a small battery bank)
  • Long battery life (up to six times the battery life of a conventional battery)
  • High efficiency between charging and discharging (very little energy loss due to heat development)
  • Higher continuous power available

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