Each cell in a battery has a negative electrode (anode) and a positive electrode (cathode) separated by a liquid or solid called the electrolyte. A group of one or more cells connected together is called a battery. Originally, batteries were not rechargeable, but some more recent batteries are rechargeable: the nickel cadmium and nickel-metal-hydride batteries. Two problems with these batteries are: (a) they lose energy capacity when not fully run down prior to charging, and (b) they lose charge when not in use. During the 1990s a new kind of rechargeable battery was developed that did not suffer from these problems. It is called the lithium ion battery, and is the main subject of this book.
Exxon Research and Engineering
While at Exxon Research and Engineering, Michael Stanley Whittingham developed the first rechargeable lithium battery. It had a titanium disulfide cathode and a lithium-aluminum anode. Bob Hamlen figured out how to manufacture it at Exxon’s facility in Branchburg, New Jersey. The battery was first used in digital watches in the 1970s.
This rechargeable battery was developed by Moli Energy, a Canadian (British Columbia) company named after the elements molybdenum and lithium. They replaced the titanium in Exxon’s battery by molybdenum. Molybdenum disulfide is cheaper and easier to work with than titanium disulfide. Starting in 1988, the batteries were used in NTT mobile phones. One battery in a hundred thousand caught fire. The problem was not caught in testing, because the testers did not think of testing under the five-day discharge, ten-hour-recharge cycle that the phone was subjected to in actual use.
In 1979 John Bannister Goodenough of Oxford University developed a lithium ion battery with a lithium-cobalt-oxide cathode and a lithium anode. Goodenough collaborated with scientists and engineers at the Atomic Energy Research Establishment in Harwell, England. Harwell’s scientists had given him verbal assurances that he would receive a share of the royalties, but when he showed up to sign the paperwork, Harwell’s lawyers were not willing to give him or Oxford University any share of the royalties. But Goodenough signed anyway, because no one else was interested in commercializing his technology.
Compact Power: Lithium Manganese Oxide
Compact Power of Troy, Michigan developed a battery based on the lithium-manganese-oxide research of Michael Thackeray & John Goodenough at Oxford University. Cobalt is toxic, and more expensive than manganese. The batteries have high power and high energy density. CPI is owned by LG Chemical of South Korea. The batteries are used in the Chevy Volt plug-in hybrid car. GM tested battery aging using a pack cycler to artificially accelerate the aging process. GM’s earlier electric car, the EV1, used lead-acid batteries, which were very heavy.
Sony’s Carbon Anode
In the 1990s Sony developed a rechargeable lithium ion battery with a carbon anode, instead of Goodenough’s metallic lithium anode. They called it a lithium ion battery, to distinguish it from a lithium battery, which had the reputation for catching fire. Further development of lithium ion batteries usually keeps Sony’s carbon anode, and instead plays with the chemical composition of the cathode.
Lithium Iron Phosphate
A new type of lithium ion battery was developed in the 1990s, the lithium iron phosphate battery. In this battery, the cathode is made of lithium iron phosphate (also called lithium ferrous phosphate). In 1993, John Goodenough, now at the University of Texas at Austin, and his student Akshaya Padhi, started the development of the lithium iron phosphate battery. They ran into some problems with electrical conductivity. They licensed their technology to Michel Armand of Hydro-Québec, who introduced a carbon coating to improve the electrical conductivity and was able to produced a working lithium iron phosphate battery. Lithium iron phosphate batteries have higher energy density, longer lifetimes and are more safe than lithium cobalt oxide.
A123 Systems developed and marketed a similar lithium iron phosphate battery, which they claimed increased electrical conductivity not by using a carbon coating, but by doping the cathode with niobium and zirconium. A patent war started. This is a complicated story. The chemistry itself, on the cause of the electrical conductivity enhancement, is still not clear, so there is no point in describing the legal battles.
Tesla designed their car so that the cells of the battery were separated from one another. So if one cell catches fire, it will not ignite any neighboring cells.