Rechargeable Batteries By: Tolaz Hewa

Chemistry behind Batteries O A battery is a package that consist of one or more galvanic cells used for the production and storage of electric energy. The power is generated because of the reaction that happens between the anode and the cathode in the galvanic cells. O Each half cell contains an electrode and an electrolyte solution. The electrolyte solution usually has ions of the electrode in them. O A Galvanic Cell is also known as voltaic cell which produces electrical energy spontaneously and

Chemistry behind Batteries O Rechargeable batteries are batteries that store electrical power. These batteries can be used multiple times and recharged. O They are cheaper, more durable, and better for our environment than disposable batteries. O Batteries have two half cells and the electricity current runs because of the difference in voltage between each electrode. O The voltage runs through the electrolyte.

Chemistry behind Batteries O Batteries are made up of plates with the help of reactive chemicals that are separated by barriers/seperators. O These plates are polarized so that all the electrons are collected on one side of the plates. O When a device is connected, a pathway is created to allow the flow of electricity from negative terminal to positive terminal. O When current happens there is also electrochemical reaction that causes the electrons to replenish

Chart of Information on Battery Types ChemistryCell VoltageEnergy Density (MJ/kg)Comments NiCd Inexpensive. High/low drain, moderate energy density. Can withstand very high discharge rates with virtually no loss of capacity. Moderate rate of self discharge. Reputed to suffer from memory effect (which is alleged to cause early failure). Environmental hazard due to Cadmium - use now virtually prohibited in Europe. Lead Acid Moderately expensive. Moderate energy density. Moderate rate of self discharge. Higher discharge rates result in considerable loss of capacity. Does not suffer from memory effect. Environmental hazard due to Lead. Common use - Automobile batteries NiMH Cheap. Not usable in higher drain devices. Traditional chemistry has high energy density, but also a high rate of self-discharge. Newer chemistry has low self-discharge rate, but also a ~25% lower energy density. Very heavy. Used in some cars. Lithium ion Very expensive. Very high energy density. Not usually available in "common" battery sizes (but see RCR-V3 for a counter-example). Very common in laptop computers, moderate to high-end digital cameras and camcorders, and cellphones. Very low rate of self discharge. Volatile: Chance of explosion if short circuited, allowed to overheat, or not manufactured with rigorous quality standards.

The advantages and disadvantages of using rechargeable batteries. O Cost O Besides the high initial cost of the battery, rechargeable batteries can recharged up to 500 times which comes to be much more efficient than buying multiple non- rechargeable batteries. O Performance O Even though at first rechargeable batteries had much lower performance then standard alkaline batteries (non-rechargeable), the technology has grown very much to a point where major companies advertise that they perform better than standard batteries. O Charging O Charging rechargeable batteries can be a pain sometimes. Especially if it forces the device to be off when charging. Some has very high discharging rate which means they need to be charged once more after not being used for a while.

The advantages and disadvantages of using rechargeable batteries. O Uses O Some batteries depending their type, they are only useful for some specific devices. Older devices may warn you not to you use Lithium-Ion which means it will not work well with them. Also because Lithium-Ion batteries are expensive, they are mainly used in computers, camera, and portable electronic devices. O Hazards O Some of the rechargeable batteries have chemicals in the that are more dangerous than alkaline batteries (especially Nickel-Cadmium). This makes them a very big threat to our environment. Some countries ban the usage of too many nickel-cadmium batteries.

More about batteries Battery TypeTotal CapacitySelf-Discharge RateUse Characteristics Nickel-Metal Hydride (NiMH) Up to 1,000, AAA. Up to 2,700 mAh, AA. Available capacities vary widely. Check the mAh rating before you buy. Does not hold charge well over long periods. Loses 4 percent per day 1, much more in warm temperatures. Works well in devices that require sudden high amperage discharge, such as digital cameras. Also works well in most other devices. Low Self Discharge Nickel-Metal Hydride (LSD NiMH) Up to 800, AAA. Up to 2,000, AA Almost all LSD batteries sold have close to these capacities. Holds charge well over long periods. Loses 15 percent per year 2, very slightly more in warm temperatures. Works well in devices that require sudden high amperage discharge, such as digital cameras. Also works well in most other devices. Nickel-Cadmium (NiCd) Up to 350 mAh, AAA. Up to 1,000 mAh, AA. Available capacities vary widely. Check the mAh rating before you buy. Loses 1 percent per day 3, slightly more in warm temperatures. Does not work well in devices that require sudden high amperage discharges. Does not work well in digital cameras, but does work well in most other devices.

What methods should be used for disposing batteries O DISPOSING OF GENERAL PURPOSE & ALKALINE BATTERIES O Alkaline batteries can be safely disposed of with normal household waste. But do not expose it to fire, there is a chance it will explode. O Companies like Duracell has stopped using mercury due to its danger on the environment since Now they are made of other non-harmful metals such as steel, zinc, and manganese. O Do not dispose too many of these batteries together at once. Because if the dead batteries have contact with each other there is a chance of reaction. O RECYCLING BATTERIES WITH OTHER CHEMISTRIES O Because of the chemical inside rechargeable, lithium, lithium ion, and zinc air batteries they should always be recycled. This included batteries for electronics such as cameras, music players, and other portable devices. O Always look for the recycle symbol on your batteries. O Car batteries should be brought back to waste management centers where they would be taken care of properly. Also there is a chance a auto worker would want your battery.

Impacts of Rechargeable batteries in portable devices on society O It has allowed for many developments in the portable electronics industry. O It has allowed us to make electronics that will be live a longer age and will not need constant change of batteries. O It has helped with the development of companies in the video game industries (Sony, Microsoft, Nintendo, Atari, etc.), portable MP3 player industries (Apple, Sony, SanDisk, etc.), and Cell phone industries (Apple, Samsung, Blackberry, etc.) O It is been a great push towards the modern convenient life we live today with the electronics.

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