09-01-2014, 01:25 PM
Battery power
[attachment=59785]
In Short
An excursion through the cell chemistries of primary and secondary batteries, from Daniell's 1836 design to today's microbatteries
The lithium-based rechargeable cell is the size of a grain of rice and has a 10-year
life span
Cell chemistries of batteries have developed as their applications have grown, from flashlamps and radios ca 70 years ago to a host of consumer products today - watches, mobile phones and laptop PCs - and bigger standby batteries for emergency use in hospitals, department stores, telephone exchanges etc. Within each of these areas there are the demands for longer lasting, cheaper and environmentally benign batteries and cells. Tony Hargreaves
Count Alessandro Volta of Italy described the first battery in a paper to the Royal Society in 1799. His battery, which became known as Volta's pile, comprised alternating discs of zinc and copper with pieces of cardboard soaked in brine between the metals. From then on several other cell chemistries were introduced and manufactured batteries soon followed. Notably, the Daniell cell was invented in 1836 by British chemist John Frederic Daniell (see Box 1). In the early days the chemistry was confined to aqueous reactions but as electrochemistry developed interest turned to non-aqueous reactions as an alternative. In this article we take a look at the range of cell chemistries exploited in primary and secondary batteries on offer, from the tiny batteries for medical implants to the 100,000,000 watt-hour molten-sodium batteries which are used in power stations for load levelling.
Primary cells
These are the disposable cells - they are discharged once and discarded - that for over a century powered small and portable equipment. Nowadays as we become more waste conscious we find that many of these cells are giving way to rechargeable (secondary) cells and batteries.
The most common primary cells are based on the zinc-manganese dioxide couple: either zinc-carbon cells or alkaline manganese cells. For a short period some manufacturers offered mercury cells, which were replaced by zinc-air batteries, and some companies now produce 3V lithium-MnO2 cells.
Zinc-carbon
This cell became commercially available in the late 1800s and was a dry cell version of the original wet Leclanché cell. (The latter was made up of a conducting solution (electrolyte) of ammonium chloride with a negative terminal of zinc and a positive terminal of manganese dioxide.) Replacing the liquid electrolyte with a gel and then sealing the whole cell made it suitable for domestic applications where portability was a key feature. These cells were developed and marketed by Ever Ready for use in radios and torches and are still popular today, though Ever Ready has now changed to Energizer and many other makes have become available.
[attachment=59785]
In Short
An excursion through the cell chemistries of primary and secondary batteries, from Daniell's 1836 design to today's microbatteries
The lithium-based rechargeable cell is the size of a grain of rice and has a 10-year
life span
Cell chemistries of batteries have developed as their applications have grown, from flashlamps and radios ca 70 years ago to a host of consumer products today - watches, mobile phones and laptop PCs - and bigger standby batteries for emergency use in hospitals, department stores, telephone exchanges etc. Within each of these areas there are the demands for longer lasting, cheaper and environmentally benign batteries and cells. Tony Hargreaves
Count Alessandro Volta of Italy described the first battery in a paper to the Royal Society in 1799. His battery, which became known as Volta's pile, comprised alternating discs of zinc and copper with pieces of cardboard soaked in brine between the metals. From then on several other cell chemistries were introduced and manufactured batteries soon followed. Notably, the Daniell cell was invented in 1836 by British chemist John Frederic Daniell (see Box 1). In the early days the chemistry was confined to aqueous reactions but as electrochemistry developed interest turned to non-aqueous reactions as an alternative. In this article we take a look at the range of cell chemistries exploited in primary and secondary batteries on offer, from the tiny batteries for medical implants to the 100,000,000 watt-hour molten-sodium batteries which are used in power stations for load levelling.
Primary cells
These are the disposable cells - they are discharged once and discarded - that for over a century powered small and portable equipment. Nowadays as we become more waste conscious we find that many of these cells are giving way to rechargeable (secondary) cells and batteries.
The most common primary cells are based on the zinc-manganese dioxide couple: either zinc-carbon cells or alkaline manganese cells. For a short period some manufacturers offered mercury cells, which were replaced by zinc-air batteries, and some companies now produce 3V lithium-MnO2 cells.
Zinc-carbon
This cell became commercially available in the late 1800s and was a dry cell version of the original wet Leclanché cell. (The latter was made up of a conducting solution (electrolyte) of ammonium chloride with a negative terminal of zinc and a positive terminal of manganese dioxide.) Replacing the liquid electrolyte with a gel and then sealing the whole cell made it suitable for domestic applications where portability was a key feature. These cells were developed and marketed by Ever Ready for use in radios and torches and are still popular today, though Ever Ready has now changed to Energizer and many other makes have become available.