One billion batteries! Considering that we are a mobile society it does make sense that batteries are ubiquitous and the likelihood that you yourself have bought a battery before is quite high. Indeed the buying of batteries is a daily and regular occurrence. Conservatively speaking billions of batteries are bought each year. Out of my own curiosity and perhaps your own, I have thought about the vast amount of raw material that must be used to go into the making of a battery, and thought that I would share my findings.
Building a battery requires certain components and their associated raw materials which ultimately affect the price of batteries. The basic battery components include:
• The Battery Casing
• The Battery Chemistry
• The Battery’s electrolyte
• The Battery’s specialized hardware
The Battery Casing
The purpose of a battery casing is for enclosing and hermetically sealing a battery body which converts chemical energy into electrical energy in order to generate current to power an electronic device. Battery casing is manufactured in layers. The casing layers are developed from various raw materials and can include one or two, for example, polyethylene terephthalate layers, a polymer layer, and a polypropylene layer. Another example may be a casing with layers of carbonized plastic.
The Battery Chemistry
As noted above a battery is a device that converts chemical energy into electrical energy. To convert chemical energy into electrical energy the battery must contain the chemical base to allow conversion to occur. Types of common chemicals used in batteries on the market today are:
1. Nickel-cadmium batteries were first invented in 1899 and are a mature energy type with moderate energy density. Nickel-cadmium is used in batteries where long life, high discharge rate and extended temperature range is important. The main applications for nickel-cadium batteries are for two-way radios, biomedical equipment and power tools.
2. Nickel-metal-hydride batteries has a higher energy density compared to nickel-cadmium but at the expense of severely reduced cycle life. Applications include mobile phones and laptop computers not much needs to be talked about here since nickel-metal hydride batteries are not too commonly used anymore for your portable consumer.
3. Lead-acid batteries are the most economical portable power source for larger power applications where weight is of little concern. Lead-acid is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems. The most common place where most of us find lead-acid batteries are in our personal vehicles. Automobiles, light trucks and vans almost always use a 12-volt, six cell, and negative grounded, lead acid automotive battery used to start gasoline or diesel engines. You will find lead-acid batteries in motorcycles, boats, snowmobiles, jet skis, farm tractors, lawn and garden tractors, SUVs, etc.
4. Lithium-ion batteries are widely used today since they offer significant benefits for portable consumers. Lithium is the lightest of all metals, it has the greatest electrochemical potential, and the largest energy density for its weight.The load characteristics of lithium are reasonably good in terms of discharge.The high cell voltage of 3.6 volts allows battery pack designs with only one cell versus three (less costly and compact). Lithium ion is a low maintenance battery with no memory and no scheduled cycling being required to prolong the battery's life. And finally Lithium-ion cells cause little harm when disposed.
5. Lithium-ion-polymer batteries are very similar to lithium-ion, but with an even far more slimmer geometry and simple packaging but of course with a higher cost per watt/hours. Main applications are cell phones and PDAs. The lithium-polymer differentiates itself from the conventional battery in the type of electrolyte used (a plastic-like film that does not conduct electricity but allows ion exchange – electrically charged atoms or groups of atoms). The polymer electrolyte replaces the traditional porous separator, which is soaked with electrolyte. The dry polymer design offers simplifications with respect to fabrication, ruggedness, safety and thin-profile geometry. Cell thickness measures as little as one millimeter (0.039 inches). Lithium polymer can be formed and shaped in any way imagined. Commercial lithium-polymer batteries are hybrid cells that contain gelled electrolyte to enhance conductivity. Gelled electrolyte added to the lithium-ion-polymer replaces the porous separator. The gelled electrolyte is simply added to enhance ion conductivity. Capacity is slightly less than that of the standard lithium-ion battery. Lithium-ion-polymer finds its market niche in wafer-thin geometries, such as PDA batteries. Lithium ion also offers improved safety – more resistant to overcharge; less chance for electrolyte leakage.
6. Reusable Alkaline – Its limited cycle life and low load current is compensated by long shelf life, making this battery ideal for portable entertainment devices and flashlights. Great batteries if you want to store on demand power for a emergencies.
The Battery’s Electrolyte
The actual conversion of chemical energy into electrochemical energy can only be done if an electron flow passes between two electrodes, an anode (the negative end) and a cathode (the positive end). The battery’s electrical current (electron flow) runs from one electrode to another through a conductive chemical called an electrolyte solution.
A basic electrolyte solution is a chemical compound (salt, acid, or base) that when dissolved in a solvent forms a solution that becomes an ionic conductor of electricity. In the battery cell the electrolyte solution is the conducting medium in which the flow of electric current between the electrodes takes place by the migrating electrons.
Since the 1970 it has been known that adding salts to polymers can enable the polymer to conduct lithium ion. This material thus can serve as an electrolyte in lithium batteries. Lithium solid polymer electrolyte batteries, when given full measure to the capacity for miniaturization of a fully solid state battery can have the highest specific energy and specific power of any rechargeable technology.
Some of the benefits that lithium solid polymer electrolytes include:
• ease of manufacturing
• immunity from leakage
• suppression of lithium dendrite formation
• elimination of volatile organic liquids
• mechanical flexibility.
The Battery’s Specialized Hardware
A battery consists of more then the casing, electrolyte, and the chemical. It requires some very specialized hardware, especially when we speak directly about a smart battery. Your typical smart battery may have a multitude of hardware componenets that when working in tandem not merely create electrical power and transfer it to a particular device but additionally sends data packets of information to the device so that the device can actually gauge the battery (at least in theory). Some of the common hardware features in a smart battery include:
1. the connector
2. the fuse
3. the charge and discharge FETs
4. the cell pack
5. the sense resistor (RSENSE)
6. the primary and secondary protection ICs
7. the fuel-gauge IC
8. the thermistor
9. the pc board
10. the EEPROM or firmware for the fuel-gauge IC.
Until next time – Dan Hagopian www.BatteryShip.com
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