Panasonic_LiIon_Overview

Panasonic_LiIon_Overview - OVERVIEW OF LITHIUM ION...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 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-edge battery technology, are excellent sources for high-energy power in a variety of portable devices, such as portable computers and cellular phones. Light weight and boasting high voltage ratings (3.6 V), these high-energy density batteries provide a variety of features that will contribute to the weight reduction and downsizing of portable products. • The Structure of Lithium Ion Batteries (Cylindrical) Structure The lithium ion battery has a three-layer, coiled structure within its case. These three layers are comprised of a positive electrode plate (made with lithium cobalt oxide as its chief active ingredient), a negative electrode plate (made with a specialty carbon as its chief active ingredient), and a separator layer. Positive Terminal PTC Element Pressure Release Valve Positive Terminal Lead Gasket Separators Insulation Plate The battery is equipped with a variety of measures to insure safety, along with a pressure release valve that releases gas if the internal pressure exceeds a specific value, thereby preventing the battery from rupturing. Exhaust Gas Hole Negative Electrode Negative Terminal Lead Case Positive Electrode Insulation Plate • Safety (UL) Panasonic’s lithium ion batteries (CGR17360, CGR17500, CGR18500, CGR18650AF, CGR18650C, CGR18650CF, CGR18650D, CGA523436B, CGA523450C, CGA633450B, CGA103450) have obtained UL1642 approval. LITHIUM ION, PAGE 6 AUGUST 2005 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 to modification 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 voltages) as the positive electrode and a highly-crystallized specialty carbon as the negative electrode. It uses an organic solvent, optimized for the specialty carbon, as the electrolytic fluid. The chemical reactions for charge and discharge are as shown below: Charge Positive Electrode Li1-x CoO2 + xLi+ + xe- LiCoO2 Discharge Charge Negative Electrode + C + xLi + xe- CLix Discharge Charge Battery as a Whole LiCoO2 + C Li1-x CoO2 + CLix Discharge The principle behind the chemical reaction in the lithium ion battery is one where the lithium in the positive electrode lithium cobalt oxide material is ionized during charge, and moves from layer to layer in the negative electrode. 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 Positive Electrode Negative Electrode Charge Li + Co O Li Li + Discharge LiCoO2 Specialty Carbon LITHIUM ION, PAGE 7 AUGUST 2005 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 to modification without notice. Contact Panasonic for the latest informatio FEATURES OF LITHIUM ION BATTERIES • High Energy Density Because the lithium ion batteries are high voltage/light weight batteries, they boast a higher energy density than rechargeable nickel cadmium (Ni-Cd) batteries or nickel metal hydride (Ni-MH) batteries. Mass Energy Density (Wh/kg) 200 Lithium-Ion Batteries 150 100 50 0 0 • Nickel Hydride Batteries Ni-Cd Batteries 50 100 150 200 250 300 350 400 450 500 Volumetric Energy Density (Wh/ ) High Voltage Lithium ion batteries produce 3.6 volts, approximately three times the voltage of rechargeable Ni-Cd batteries or Ni-MH batteries. This will make it possible to make smaller, lighter equipment. Ni-Cd Ni-Cd Ni-Cd Li-Ion No Memory Effect Lithium ion batteries have none of the memory effects seen in rechargeable Ni-Cd batteries (“memory effect” refers to the phenomenon where the apparent discharge capacity of a battery is reduced when it is repetitively discharged incompletely and then recharged). Battery: CGR17500 4.0 Voltage (V) • One cycle One cycle 3.5 One cycle One cycle 250 cycles 3.0 Discharge: 133 mA at 20˚C 2.5 Charge: Constant voltage: 4.1 V, with a maximum of 500 mA current for two hours at 20˚C Discharge: 133 mA, completed after two hours, at 20˚C 0 2 2 2 2 0 Hold Time (h) 4 6 8 Flat Discharge Voltage The use of the specialty carbon creates an extremely flat discharge voltage profile, allowing the production of stable power throughout the discharge period of the battery. 5.0 Battery: CGR18650 Discharge: 250 mA 4.5 Voltage (V) • 2 Hold Time (h) 4.0 Panasonic's Specialty Carbon 3.5 Coke (Panasonic's Trial Product) 3.0 2.5 2.0 0 500 1000 1500 Discharge Capacity (mAh) LITHIUM ION, PAGE 8 AUGUST 2005 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 to modification without notice. Contact Panasonic for the latest information. ...
View Full Document

Ask a homework question - tutors are online