Course:SPPH381B/TermProject/Alkaline battery

History

Alessandro Volta invented the voltiac pile - the first battery.

Alessandro Volta of Italy built the voltaic pile and discovered the first practical method of generating electricity.

Batteries provided the main source of electricity before the development of electric generators and electrical grids around the end of the 19th century. The first battery was constructed in 1800 by Italian Alessandro Volta. This voltaic pile battery consisted of pairs of copper and zinc discs piled on top of each other, separated by a layer of cloth soaked in brine (i.e., the electrolyte).

Battery Involves electrochemical cells that transform chemical energy into electricity. All batteries utilize similar procedures to create electricity; however, variations in materials and construction have produced different types of batteries. "Primary" batteries are able to produce current as soon as assembled, but once the active elements are consumed, they can't be electrically recharged. The development of the lead-acid battery and subsequent "secondary" or "rechargeable" types allows the energy to be restored to the cell, extending the life of permanently assembled cells.

Introduction

Alkaline battery is based on the reaction between zinc (Zn) and manganese dioxide (MnO2). Alkaline battery is so named because the electrolyte used in it is potassium hydroxide, a purely alkaline substance. It has longer shelf life. Leakage is low in this battery. It has better dimensional stability. This also performs equally well at ambient temperature as well as at low temperature. Alkaline battery has low internal resistance. Alkaline batteries account for 80% of manufactured batteries in the US and over 10 billion individual units produced worldwide. In Japan, alkaline batteries account for 46% of all primary battery sales. In Switzerland, alkaline batteries account for 68%, in the UK 60% and in the EU 47% of all battery sales include secondary types. Alkaline batteries are available in various sizes according to the applications (such as AAA, AA, C, D, 9 V and others). All of these configurations are likely to be used on gadgets immediately after purchase, which make them suitable for use even during emergency situations. Additionally, long shelf life offered by these batteries (ranging from three to four years) makes them suitable for storage. This feature of the alkaline battery chemistry is expected to offer a competitive advantage as compared to the rechargeable batteries of other chemistries.

The alkaline batteries come in various sizes ranging from AAA to AA, C, D, 9 V and others. AAA and AA are suitable for low-drain applications whereas AA is used for high-drain applications. C, D and 9 V are suitable for high-drain applications as well. Others include micro alkaline button cells, coin cells, AAAA which are used in few industrial and medical applications. AA is the most widely used alkaline battery cell size, while the AAA size is the fastest growing.

Self-discharge rate <0.3%/monthTime durability 5–10 yearsNominal cell voltage 1.5 V

Recharging of alkaline battery

Another type of alkaline batteries are secondary rechargeable alkaline battery, which allows reuse of specially designed cells. Attempts to recharge may cause rupture, or the leaking of hazardous liquids which can corrode the equipment. However, attempts at recharging alkaline cells a highly limited number of times (10 or fewer times with reduced capacity after each charge) are reported and chargers are available commercially.

The usage of these batteries is limited to specific applications. However, one of the major advantages of rechargeable alkaline batteries is that it is likely to find usage in all applications that need primary alkaline batteries. These batteries are manufactured through a small variation in chemical composition of alkaline batteries. This makes these batteries leak-proof even during the recharging process. Some of the key features of rechargeable alkaline batteries include:

1. These batteries are likely to be rechargeable for nearly 500 charges. However, it needs be recharged at proper intervals.

2. Compared with the cost involved per charge, alkaline batteries offer low-cost rechargeable batteries, in comparison to the other chemistries.

3. Rechargeable alkaline batteries also offer a voltage output of 1.5 volts, while other rechargeable chemistries offer an output voltage of 1.2 volts.

4. These batteries are environment-friendly and therefore are likely to be disposed of easily after complete discharge. However, proper recycling operation is needed for other rechargeable chemistries.

5. These batteries are ready-to-use and are expected to power the device immediately after purchase.

Production

In an alkaline battery cell, the powder zinc serves as anode, manganese dioxide serves as cathode and potassium hydroxide serves as electrolyte.

The body of the battery is made of a hollow steel drum. This drum contains all materials of the battery and it also serves as cathode of the battery. The positive terminal of the battery is projected from the top of this drum. Fine grained manganese dioxide (MnO2) powder mixed with coal dust is molted to the inner peripheral surface of the empty cylindrical drum. This molded mixture serves as cathode mixture of the alkaline battery. The inner surface of the thick layer of cathode mixture is covered with paper separator. The central space, inside this paper separator is filled by zinc powder with potassium hydroxide electrolyte. The zinc serves as anode and its powder form increases the contact surface. The paper separator soaked with potassium hydroxide, holds the electrolyte in between cathode (MnO2) and anode(Zn). A metallic pin (preferably made of brass) is inserted along the central axis of the alkaline battery to collect negative charge. This pin is called negative collector pin. This pin is in touch with metallic end sealed cap. There is a plastic cover just inside the metallic end sealed cap and this plastic cover electrically separates positive steel drum and negative end cap of alkaline battery.

Chemical reaction

The half-reactions involved are:

• Zn(s) + 2OH−(aq) → ZnO(s) + H2O(l) + 2e− [Eoxidation° = +1.28 V]
• 2MnO2(s) + H2O(l) + 2e− → Mn2O3(s) + 2OH−(aq) [Ereduction° = +0.15 V]

Overall reaction:

• Zn(s) + 2MnO2(s) ⇌ ZnO(s) + Mn2O3(s) [e° = +1.43 V]

An alkaline battery cell is rated for 1.5 V. A new non discharged alkaline cell shows a voltage of 1.50 to 1.65 V. The average voltage under load condition can be 1.1 to 1.3 V. AA alkaline cell is generally rated for 700 mA

Life cycle

Lithium-ion Nickel Cobalt Manganese (Li-NCM) battery life cycle assessment

Resource extraction Manufacturing of alkaline batteries starts with the resource extraction of graphite, nickel and manganese through open pit and underground mining method.

Primary manufacturing The first step in making alkaline batteries is to manufacture cathode which involves granulation of manganese dioxide, black carbon (graphite) and electrolyte(potassium hydroxide in solution) and then the mixture is pressed into hollow cylinders called preforms. They are next inserted into nickel-plated steel can, together making up the cathode. This is further accompanied by manufacturing of separator (either paper or porous synthetic fiber is used) and manufacturing of anode (gel composed primarily of zinc powder, along with other materials including a potassium hydroxide electrolyte).

Secondary manufacturing Alkaline battery is sealed with three connected components: brass nail that is inserted into the middle of the can, serving as the current collector, plastic seal, and a metal end cap. This is performed by a welding machine which fuses nails on top of the battery and another welding machine inserts the cap into the negative end of the battery.

Support infrastructure & Power Support infrastructure for alkaline batteries involve the building of roads, railways, ships and airplanes. The building of roadways involve planning, clearing the road of any obstructions that may disturb the pathway and leveling the land. Modern day road construction equipment such as hydraulic excavators, motor graders, asphalt pavers, wheel loaders and vibratory compactors play an important role in constructing the roadways.The rails are connected to each other by railroad ties (called sleepers in Europe), which may be made of wood or concrete. The rails are usually bolted to the ties. The ties are set into the loose gravel or ballast. Ballast often consists of loose stones that help transfer the load to the underlying foundation accompanied by the electrical power supplied to the railways. For a port to efficiently send and receive cargo, it requires infrastructure that includes docks, bollards, pilings, cranes, bulk cargo handling equipment along with equipment and organization supporting the role of the facilities. Cargo airlines often have their own on-site and adjacent infrastructure to transfer parcels between ground and air.

Transportation There are no special restrictions on the international transportation of alkaline manganese batteries by land (ADR Agreement), rail (RID Regulations), sea (IMDG Code), or air (ICAO/IATA Regulations).

Disposal/recycling Batteries can be disposed off with domestic waste (in household use) and if in bulk quantities, they are disposed off in a hazardous waste landfill but now they can be recycled as well.

Process details in each major step of life cycle

1. Graphite mining (Resource extraction) - Open pit and underground mining

2. Manufacturing of cathode and anode (Primary manufacturing) - Granulation

3. Sealing (Secondary manufacturing) - Welding

4. Ground, ship and air (Transportation) - Air transport

5. Railroad construction (Support infrastructure and power) - Track ballast

6. Recycling (Disposal/recycling) - Hydrometallurgy

Conclusion

Battery life can be extended by storing the batteries at a low temperature, as in a refrigerator or freezer, which slows the chemical reactions in the battery. Such storage can extend the life of alkaline batteries by ~5%; while the charge of rechargeable batteries can be extended from a few days up to several months. In order to reach their maximum voltage, batteries must be returned to room temperature; discharging an alkaline battery at 250 mAh at 0°C is only half as efficient as it is at 20°C. As a result, alkaline battery manufacturers like Duracell do not recommend refrigerating or freezing batteries. Ordinary dry cells are used in most flashlight batteries. These cells use ammonium chloride as the electrolyte. Alkaline cells, on the other side last longer and can supply heavier currents.

So, what will replace batteries in the future? There have been a lot of technologies suggested, including some that incorporate things like mud, bugs and garbage. Certainly fuel cells represent a promising technology, with the promise of powering a device like a laptop computer for days. In fact, we believe they will eventually replace some batteries. Fuel cells are similar to batteries in that they use a chemical reaction to create electricity. However, a fuel cell uses a fuel (i.e., hydrogen, natural gas, etc.) to create the electricity. Today, the biggest barrier to the advent of the fuel cell continues to be the cost and the need to supply fuel. Still, it must be remembered that the future replacement technology, whatever it is, will replace a very well-known and trusted device.