Lithium-ion (Li-ion) batteries are comprised of cells that employ lithium intercalation compounds as the positive and negative materials. As a battery is cycled, lithium ions (Li+) exchange between the positive and negative electrodes. They are also referred to as rockingchair batteries as the lithium ions “rock” back and forth between the positive and negative electrodes as the cell is charged and discharged.
The positive electrode material is typically a metal oxide with a layered structure, such as lithium cobalt oxide (LiCo02), or a material with a tunneled structure, such as lithium manganese oxide (LiMn20 4), on a current collector of aluminum foil. The negative electrode material is typically a graphitic carbon, also a layered material, on a copper current collector. In the charge/ discharge process, lithium ions are inserted or extracted from interstitial space between atomic layers within the active materials.
The first batteries to be marketed, and the majority of those currently available, utilize LiCo02 as the positive electrode material. Lithium cobalt oxide offers good electrical performance, is easily prepared, has good safety properties, and is relatively insensitive to process variation and moisture. More recently lower cost or higher performance materials, such as LiMn20 4 or lithium nickel cobalt oxide (LiNi l _ xCox0 2), have been introduced, permitting development of cells and batteries with improved performance. The batteries that were first commercialized employed cells with coke negative electrode materials. As improved graphites became available, the industry shifted to graphitic carbons as negative electrode materials as they offer higher specific capacity with improved cycle life and rate capability.
The Li-ion battery market has grown in a decade from an R&D interest to sales of over 400 million units in 1999. Market value at the OEM level was estimated to be $1.86 billion in 2000. 1 By 2005, the market is expected to grow to over 1.1 billion units with value of over $4 billion (¥455 billion),2 while the average unit price is expected to fall 46% from 1999 to 2005.
Market interest in this cost-effective, high performance, and safe technology
has driven spectacular growth, as illustrated in Fig. 35.1. This technology has rapidly become the standard power source in a broad array of markets, and battery performance continues to improve as Li-ion batteries are applied to an increasingly diverse range of applications.
To meet market demand, an array of designs has been developed, including spiral wound cylindrical, wound prismatic and fiat plate prismatic designs in small (0.1 Ah) to large (160 Ah) sizes. Applications now addressed with Li-ion batteries include consumer electronics, such as cell phones, laptop computers, and personal data assistants, as well as military electronics, including radios, mine detectors and thermal weapons sights. Anticipated applications include aircraft, space craft, satellites, and electric or hybrid electric vehicles.
Li-ion Battery Advantages & Disadvantages:
The major advantages and disadvantages of Li-ion batteries, relative to other types of batteries, are summarized in Table below. The high specific energy ( ~ 150 Wh/kg) and energy density ( ~ 400 Wh/L) of commercial products makes them attractive for weight or volume sensitive applications.
Li-ion batteries offer a low self-discharge rate (2% to 8% per month) long cycle life (greater than 1000 cycles) and a broad temperature range of operation (charge at -20°C to 60°C, discharge at -40°C to 6S°C), enabling their use in a wide variety of applications.
A wide array of sizes and shapes is now available from a variety of manufacturers. Single cells typically operate in the range of 2.5 to 4.2 V, approximately three times that of Ni-Cd or Ni-MH cells, and thus require fewer cells for a battery of a given voltage.
Li-ion batteries can offer high rate capability. Discharge at 5C continuous, or 25C pulse, has been demonstrated.
The combination of these qualities within a cost effective, package has enabled diverse application of the technology.
Advantages & Disadvantages of Li-ion battery
|
|
Advantages
|
Disadvantages
|
| Sealed cells; no maintenance required |
Moderate initial cost |
| Long cycle life |
Degrades at high temperature |
| Broad temperature range of operation |
Need for protective circuitry |
| Long shelf life |
Capacity loss or thermal runaway when over-charged. |
| Low self-discharge rate |
Venting and possible thermal runaway when crushed |
| Rapid charge capability |
Cylindrical designs typically offer lower power density than Ni-Cd or
Ni-Mh |
| High rate and high power discharge capability |
|
| High coulombic and energy efficiency |
|
| High specific energy and energy density |
|
| No memory effect |
|
A disadvantage of Li-ion batteries is that they degrade when discharged below 2 V and may vent when overcharged as they do not have a chemical mechanism to manage overcharge, unlike aqueous cell chemistries.
Li-ion batteries typically employ management circuitry and mechanical disconnect devices to provide protection from over-discharge, overcharge or over temperature conditions. Another disadvantage of Li-ion products is that they permanently lose capacity at elevated temperatures (65°C), albeit at a lower rate than most Ni-Cd or Ni-MH products.
Source:
Needbattery.com
We can see laptops every where, they’re becoming more and more popular as they are light, portable and personal to each of us. It is like they are nondetachable part of our daily life.
But behind every Laptop is lying the power source which runs everything from CPU to DVD Rom, laptop battery at the edge of technology which is getting thinner, more powerful and easier to handle everyday thanks to improvements and researches have been made.
But do we know enough about them? How to charge-discharge them, how long they will run our laptop and when is the time to replace them…
These articles will help you get a better understanding of a laptop battery and it’s functionality:
-
Does using the wireless network card drain a laptop battery?
Read More…
The Lead-Acid battery is manufactures in variety of sizes and designs ranging
from less than 1 to over 10,000 Ah.
Table below lists many of the various types of lead-acid batteries that are
available:
| Types and Characteristics of Lead-Acid Batteries |
|
Type
|
Construction
|
Typical Application
|
| SLI (Starting, lighting, ignition) |
Flat-pasted plates (option: maintenance-free construction) |
Automotive, marine, aircraft, diesel engines in vehicles and
for stationary power |
| Traction |
Flat-pasted plates; tubular and
gauntlet plates |
Industrial trucks (material handling) |
| Vehicular Propulsion |
Flat-pasted plates; tubular and gauntlet plates; also composite construction |
Electric vehicles, golf carts, hybrid vehicles, mine cars, personnel carriers and electric scooter. |
| Submarine |
Tubular plates; flat-pasted plates |
Submarines |
| Stationary (mcludmg energytorage
types such as charge
retention, solar photovoltruc,
load leveling) |
Plante;* Manchester;* tubular and gauntlet plates; flat-pasted plates;
circular conical plates |
Standby emergency power:
telephone exchange, uninterruptible power systems (UPS battery), load leveling,
signaling |
|
Portable
|
Flat-pasted plates (gelled electrolyte, electrolyte
absorbed in separator); spirally wound electrodes; tubular plates
|
Consumer and instrument applications: portable tools,
appliances, lighting, emergency lighting, radio, TV, alarm systems
|
| * Now rarely used. |
The lead-acid battery has been a successful article of commerce for over a century. Its production and use continue to grow because of new applications for battery power in energy storage, emergency power, and electric and hybrid vehicles (including off-road vehicles) and because of the increased number of vehicles for which it provides the energy for engine starting, vehicle lighting, and engine ignition (SLI) and UPS battery.
Courtesy of "http://knol.google.com"
Its sales represent approximately 40 to 45% of the sales value of all batteries in the world, or a market value, in 1999, of about $15 billion at manufacturers’ levels and 2 to 3 times this value at retail levels. (These values do not include some countries such as Russia and China, for which complete market data are not available.) Read More…
Electrochemical cells and batteries are identified as primary (non-rechargeable) or secondary (rechargeable), depending on their capability of being electrically recharged. Within this classification, other classifications are used to identify particular structures or designs.
- Primary Cells or Batteries
These batteries are not capable of being easily or effectively recharged electrically and, hence, are discharged once and discarded. Many primary cells in which the electrolyte is contained by an absorbent or separator material (there is no free or liquid electrolyte) are termed “dry cells.” Read More…
A battery is a device that converts the chemical energy contained in its active materials directly into electric energy by means of an electrochemical oxidation-reduction (redox) reaction. In the case of a rechargeable system, the battery is recharged by a reversal of the process. This type of reaction involves the transfer of electrons from one material to another
through an electric circuit. In a nonelectrochemical redox reaction, such as rusting or burning, the transfer of electrons occurs directly and only heat is involved. As the battery electrochemically converts chemical energy into electric energy, it is not subject, as are combustion or heat engines, to the limitations of the Carnot cycle dictated by the second law of thermodynamics.
Batteries, therefore, are capable of having higher energy conversion efficiencies. While the term “battery” is often used, the basic electrochemical unit being referred to is the “cell.” A battery consists of one or more of these cells, connected in series or parallel, or both, depending on the desired output voltage and capacity.* Read More…
A cell is the basic electrochemical unit providing a source of electrical energy by direct conversion of chemical energy. The cell consists of an assembly of electrodes, separators, electrolyte, container and terminals.
A battery consists of one or more electrochemical cells, electrically connected in an appropriate series/parallel arrangement to provide the required operating voltage and current levels, including, if any, monitors, controls and other ancillary components (e.g. fuses, diodes), case, terminals and markings. (Although much less popular, in some publications, the term “battery” is considered to contain two or more cells.)
Popular usage considers the “battery” and not the “cell” to be the product that is sold or provided to the “user.”
The term ” cell” will be used when describing the cell component of the battery and its chemistry. The term ” battery” will be used when presenting performance characteristics, etc. of the product. Most often, the electrical data is presented on the basis of a single-cell battery. The performance of a multicell battery will usually be different than the performance of the individual cells or a single-cell battery
source:
needbattery.com
You are going to buy a new battery for your power tool? That’s all you know so far since your power tool isn’t working properly and you guess you would need a new battery. But it’s hard to read the battery label and specification, In fact, some would even say that power tool batteries essentially have a language of their own.
For those who are unfamiliar with the terminology that accompanies power tool batteries, making the correct portable power decisions becomes that much more difficult. And since there are quite a few different terms that are somewhat unique to the world of power tool batteries, here are 3 that will make the battery selection process a little easier to understand:
- Amp hours (Ah): A unit of electric charge that measures capacity. In power tool batteries, this is a very key measurement as it represents how long it can deliver a certain amount of charge before it runs out. The measurement milliAmp hour (mAh) is most commonly used to represent how much charge is left in a particular battery. It’s important to note that Amp hours don’t dictate the flow of electrons at any given moment, meaning that the actual length of time that an Amp-hour symbolizes can change depending on how efficiently the battery is being used. Read More…
Microsoft has certainly had some ups and downs with its products over the years, but we’re pretty sure the company’s new “InstaLoad” technology falls somewhere between a home run and the best thing it’s ever done.
It promises to do nothing short of redefine the way you insert batteries, and let you shove them into devices without any regard for positive or negative polarity. That’s apparently possible thanks to a patented battery contact design, which Microsoft says “simply works,” and is compatible with a whole range of battery sizes (both standard and rechargeable batteries ).
What’s more, Microsoft is now already licensing the technology to third party device suppliers, and is even offering a royalty-free license for suppliers and manufacturers of accessibility products.
Still no word on when the first devices using the technology will be available, but Microsoft already counts Duracell and flashlight battetry -manufacturer AE Light among its partners.
Source:
engadget.com
Lithium-ion battery Life Span
Lithium-ion battery packs are expensive, so if you want to make yours to last longer, here are some things to keep in mind:
- Lithium ion chemistry prefers partial discharge to deep discharge, so it’s best to avoid taking the battery all the way down to zero. Since lithium-ion chemistry does not have a “memory”, you do not harm the battery pack with a partial discharge. If the voltage of a lithium-ion cell drops below a certain level, it’s ruined.
- Avoid heat, which degrades the batteries. Read More…
