Apr 19 2011
In June 1936, workers constructing a new railway near the city of Baghdad uncovered an ancient tomb. Relics in the tomb allowed archeologists to identify it as belonging to the Parthian Empire. The Parthians, although illiterate and nomadic, were the dominating force in the Fertile Crescent area between 190 BC to 224 AD. It is known that in 129 BC they had acquired lands up to the banks of the Tigris River, near Baghdad.
Among the relics found in the tomb was a clay jar or vase, sealed with pitch at its top opening. An iron rod protruded from the centre, surrounded by a cylindrical tube made of wrapped copper sheet. The height of the jar was about 15 cm, and the copper tube was about 4 cm diameter by 12 cm in length. Tests of replicas, when filled with an acidic liquid such as vinegar, showed it could have produced between 1.5 and 2 Volts between the iron and copper. It is suspected that this early battery, or more than one in series, may have been used to electroplate gold onto silver artifacts. A German archeologist, Dr. Wilhelm Konig, identified the clay pot as a possible battery in 1938.
In 1747 Sir William Watson demonstrated in England that a current could be sent through a long wire, using the conduction through the earth as the other conductor of the circuit.
In 1786, Luigi Galvani was remarkably close to discovering the principle of the battery, but missed it. In 1800, Alessandro Volta published details of a battery: that battery was made by piling up layers of silver, paper or cloth soaked in salt, and zinc. Many triple layers were assembled into a tall pile, without paper or cloth between zinc and silver, until the desired voltage was reached. Even today the French word for battery is ‘pile’ (English pronunciation “peel”.) Volta also developed the concept of the electrochemical series, which ranks the potential produced when various metals are in contact with an electrolyte. How handy for us that he was well known for his publications and received recognition for this through the naming of the standard unit of electric potential as the Volt.
The Voltaic Pile was not good for delivering currents for long periods of time. This restriction was overcome in the Daniell Cell. British researcher John Frederich Daniell developed an arrangement where a copper plate was located at the bottom of a wide-mouthed jar. A cast zinc piece commonly referred to as a crowfoot, because of its shape, was located at the top of the plate, hanging on the rim of the jar. Two electrolytes, or conducting liquids, were employed. A saturated copper sulphate solution covered the copper plate and extended halfway up the remaining distance toward the zinc piece. Then a zinc sulphate solution, a less dense liquid, was carefully poured in to float above the copper sulphate and immerse the zinc. As an alternative to zinc sulphate, magnesium sulphate or dilute sulphuric acid was sometimes used. The Daniell Cell was one of the first to incorporate mercury, by amalgamating it with the zinc anode to reduce corrosion when the batteries were not in use. This battery, which produced about 1.1 Volts, was used to power telegraphs, telephones, and even to ring doorbells in homes for over 100 years. The applications were all stationary ones, because motion would mix the two electrolyte liquids.
In 1859, Raymond Gaston Planté made a cell by rolling up two strips of lead sheet separated by pieces of flannel, and the whole assembly was immersed in dilute sulphuric acid. By alternately charging and discharging this cell, its ability to supply current was increased. An improved separator was obviously needed to resist the sulphuric acid.
1866 was the year of the Leclanchè carbon-zinc battery: it could be used in various positions and moved about without spilling. Carbon-zinc dry cells are sold to this day in blister packages labeled “heavy duty” and “transistor power”. The anode of the cell was zinc, which was made into a cup or can which contained the other parts of the battery. The cathode was a mixture of eight parts manganese dioxide with one part of carbon black, connected to the positive post or button at the top of the battery by a carbon collector rod. The electrolyte paste may also contain some zinc chloride. Around 1960, sales of Leclanché cells were surpassed by the newer alkaline-manganese batteries.
In 1881, Camille Faure‘s acid battery used a grid of cast lead packed with lead oxide paste, instead of lead sheets. This improved its ability to supply current. It formed the basis of the modern lead acid battery used in autos, particularly when new separator materials were developed to hold the positive plates in place, and prevent particles falling from these plates from shorting out the positive and negative plates from the conductive sediment.
Between 1898 and 1908, Thomas Edison, the most prolific of all American inventors, developed an alkaline cell with iron as the anode material and nickelic oxide as the cathode material. The electrolyte used was potassium hydroxide, the same as in modern nickel-cadmium and alkaline batteries. The cells were well suited to industrial and railroad use. They survived being overcharged or remaining uncharged for long periods of time. Their voltage (1 to 1.35 Volts) was an indication of their state of charge.
In parallel with the work of Edison, but independently, Jungner and Berg in Sweden developed the nickel-cadmium cell. In place of the iron used in the Edison cell, they used cadmium, with the result that it operated better at low temperatures, self-discharged itself to a lesser degree than the Edison cell and could be trickle-charged, that is, charged at a much-reduced rate. In a different format and using the same chemistry, nickel-cadmium cells are still made and sold.
The alkaline-manganese battery, or as we know it today, the alkaline battery, was developed in 1949 by Lew Urry at the Eveready Battery Company Laboratory in Parma, Ohio. Alkaline batteries could supply more total energy at higher currents than the Leclanché batteries. Further improvements since then have increased the energy storage within a given size package.
In 1950, Samuel Ruben (an independent inventor) developed the zinc-mercuric oxide alkaline battery, which was licensed to the P.R. Mallory Co., which later became Duracell, International. Mercury compounds have since been eliminated from batteries to protect the environment.
For many years, nickel-cadmium had been the only suitable battery for portable equipment from wireless communications to mobile computing. Nickel-metal-hydride and lithium-ion emerged in the early 1990s, fighting nose-to-nose to gain customer’s acceptance.
Pioneer work with the lithium battery began in 1912 under G.N. Lewis, but it was not until the early 1970s when the first non-rechargeable lithium batteries became commercially available. Lithium is the lightest of all metals, has the greatest electrochemical potential and provides the largest energy density for weight.
Attempts to develop rechargeable lithium batteries failed due to safety problems. Because of the inherent instability of lithium metal, especially during charging, research shifted to a non-metallic lithium battery using lithium ions. Although slightly lower in energy density than lithium metal, lithium-ion is safe, provided certain precautions are met when charging and discharging. In 1991, the Sony Corporation commercialized the first lithium-ion battery. Other manufacturers (e.g. A&T Battery Co.) followed suit.
Today, lithium-ion is the fastest growing and most promising battery chemistry.
In the figure below, a comparison of energy densities of various small, sealed common battery systems can be observed.
Below you will see a battery pack under construction by Genport designed for Small Vehicles.
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