lithium-ion battery

Lithium-Ion

Battery By QingjieBao

• A lithium-ion battery (sometimes Li-ion battery or LIB) is a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge, and back when charging.

Introduction

Battery History and Basics

The modern battery was developed by Italian physicist Alessandro Volta in 1800.

Construction

•The three primary functional components of a lithium-ion battery are the anode, cathode, and electrolyte. The anode of a conventional lithium-ion cell is made from carbon, the cathode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.

Formats

•Li-ion cells are available in various formats, which can generally be divided into four groups:• Small cylindrical (solid body without terminals, such as those used in laptop batteries)• Large cylindrical (solid body with large threaded terminals)• Pouch (soft, flat body, such as those used in cell phones)• Prismatic (semi-hard plastic case with large threaded terminals, often used in vehicles' traction packs)

The Voltaic Pile

Iphone4 and 3 different 3gs and 4, the main difference is: 4 screen resolution higher

than 3g retina screen for sharper display4 camera 5 million pixels, and can shoot 720p HD video, and flash. There is also a front camera, you can video chat (FaceTime).3gs 3 million pixels, there is no front camera, no flash.Now 3gs and 4 can multi-task and folder, because Ann is ios4.2.The common drawback of all the iPhone is: not a long life time, a typical day down you have to charge, but can not change the battery, you can not insert the memory card, but users can not browse the files, only download the application to use.

Charging

• During charging, an external electrical power source (the charging circuit) applies a higher voltage (but of the same polarity) than that produced by the battery, forcing the current to pass in the reverse direction.

Advantages

•Wide variety of shapes and sizes efficiently fitting the devices they power.• Much lighter than other energy-equivalent secondary batteries.• High open circuit voltage in comparison to aqueous batteries (such as lead acid, nickel-metal hydride and nickel-cadmium). This is beneficial because it increases the amount of power that can be transferred at a lower current.• No memory effect.

Disadvantages

•Charging forms deposits inside the electrolyte that inhibit ion transport. Over time, the cell's capacity diminishes. The increase in internal resistance reduces the cell's ability to deliver current. •High charge levels and elevated temperatures hasten capacity loss.

Safety requirements

•If overheated or overcharged, Li-ion batteries may suffer thermal runaway and cell rupture.

Battery types

Nickel-cadmiumNickel-cadmium: (NiCd)

rechargeable,

“memory effect”

Nickel-metal hydrideNickel-metal hydride: (NiMH)

rechargeable

no “memory effect”

Lithium-IonLithium-Ion: (Li-Ion)

rechargeable

no “memory effe

Memory Effect

• The Memory EffectMemory Effect: (generally) When a battery is repeatedly recharged before it has discharged more than half of its power, it will “forget” its original power capacity.

Lithium

•Periodic Table Symbol: Li•Atomic Weight: 3 (light!)•Highly reactive, with a high energy density.•Used to treat manic-depression because it is particularly effective at calming a person in a “manic” state.

The Periodic Table

Specifications and design

•Specific energy density ： 150 to 250 W.h/kg or 540kj/kg•Volumetic energy density ： 250 to 630 W.h/l or 900 to 1900 J/cm³•Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285 W·h/l)

Internal resistance

•The internal resistance of standard (Cobalt) lithium-ion batteries is high compared to both other rechargeable chemistries such as nickel-metal hydride and nickel-cadmium, and LiFePO4 and lithium-polymer cells.

Conclusion Finally, I believe Lithium-Ion Battery is very usefu

l because its high energy density allows batteries them to power complex machinery and it also recharge quickly and hold their charge longer.

Links to References

http://electronics.howstuffworks.com/battery.htm

http://www.batteryuniversity.com ttp://www.nano.gov/html/research/

industry.html http://everything2.com/e2node/Lithium

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