Lithium ion - overview

OVERVIEW OF LITHIUM ION BATTERIES
Meeting the Needs of Portable Electronic Devices:
Lithium Ion Batteries
• Overview
Panasonic lithium ion batteries, products of Panasonic’s long experience with batteries and leading-edgebattery technology, are excellent sources for high-energy power in a variety of portable devices, such as por-table computers and cellular phones. Light weight and boasting high voltage ratings (3.6 V), these high-energydensity batteries provide a variety of features that will contribute to the weight reduction and downsizing ofportable products.
• Structure
The Structure of Lithium Ion Batteries (Cylindrical)
The lithium ion battery has a three-layer, coiledstructure within its case. These three layers arecomprised of a positive electrode plate (made withlithium cobalt oxide as its chief active ingredient), a negative electrode plate (made with a specialty carbon as its chief active ingredient), and a The battery is equipped with a variety of measuresto insure safety, along with a pressure release valve that releases gas if the internal pressure exceeds a specific value, thereby preventing the battery from • Safety (UL)
Panasonic’s lithium ion batteries (CGR17500,CGR18650HG, CGR18650A, CGA533048,CGA633450A, CGA103450) have obtained UL1642approval.
LITHIUM ION
APRIL 2002
This information is generally descriptive only and is not intended to make or imply any representation, guarantee or warranty with respect to any cells and batteries. Cell and battery designs/specifications are subject tomodification without notice. Contact Panasonic for the latest information.
OVERVIEW OF LITHIUM ION BATTERIES - CONTINUED
• Battery Reaction
The lithium ion battery makes use of lithium cobalt oxide (which has superior cycling properties at high volt-ages) as the positive electrode and a highly-crystallized specialty carbon as the negative electrode. It uses anorganic solvent, optimized for the specialty carbon, as the electrolytic fluid.
The chemical reactions for charge and discharge are as shown below: Positive Electrode
Negative Electrode
Battery as a Whole
The principle behind the chemical reaction in the lithium ion battery is one where the lithium in the positiveelectrode lithium cobalt oxide material is ionized during charge, and moves from layer to layer in the negativeelectrode. During discharge, the ions move to the positive electrode and return to the original compound.
Schematic Diagram of the Chemical Reaction of the Lithium Ion Battery
LITHIUM ION
APRIL 2002
This information is generally descriptive only and is not intended to make or imply any representation, guarantee or warranty with respect to any cells and batteries. Cell and battery designs/specifications are subject tomodification without notice. Contact Panasonic for the latest information.
FEATURES OF LITHIUM ION BATTERIES
• High Energy Density
Because the lithium ion batteries are high voltage/light weight batteries, they boast ahigher energy density than rechargeable nickel cadmium (Ni-Cd) batteries or nickel • High Voltage
Lithium ion batteries produce 3.6 volts,approximately three times the voltage ofrechargeable Ni-Cd batteries or Ni-MHbatteries. This will make it possible to • No Memory Effect
Lithium ion batteries have none of the memoryeffects seen in rechargeable Ni-Cd batteries (“memory effect” refers to the phenomenon where the apparent discharge capacity of abattery is reduced when it is repetitively discharged incompletely and then recharged).
Charge: Constant voltage: 4.1 V, with a
Discharge: 133 mA at 20˚C
2.5 maximum of 500 mA current for two hours at 20˚C Discharge: 133 mA, completed after two hours,
at 20˚C
• Flat Discharge Voltage
The use of the specialty carbon creates anextremely flat discharge voltage profile, allowing Battery: CGR18650
the production of stable power throughout the Discharge: 250 mA
LITHIUM ION
APRIL 2002
This information is generally descriptive only and is not intended to make or imply any representation, guarantee or warranty with respect to any cells and batteries. Cell and battery designs/specifications are subject tomodification without notice. Contact Panasonic for the latest information.

Source: http://lukask.dyndns.org/files/datasheet/Diverses/Battery/Lithium/Panasonic_LiIon_Overview.pdf