As the automotive world becomes increasingly “green,” batteries are becoming omnipresent within our engines. But as essential as they are in the process of an ecological transition of transport, the classic lithium-ion batteries, which represent the vast majority, are not without flaws. Flaws continually pointed out by critics of electric vehicles – and which, in the current state of affairs, remain a thorn in the side of engineers. Although EVs emit 77% less CO2 throughout their lifetime compared to an internal combustion engine – according to a study by T&E published in April 2020 –, these batteries emit between 5 and 17 tons of CO2 between their production, use, and recycling (figures released by the Swedish Environmental Research Agency).
SOME PROBLEMS ARISE.
The main issue: the extraction of lithium, an alkali metal mainly found in South America (Argentina, Chile, and Bolivia accounting for nearly 60% of global resources), in China (27% of global resources), but also in Australia and the United States. This leads to numerous soil pollution problems due to the products used to synthesize lithium, but above all to the plundering of water reserves to the detriment of the population of lithic regions. There are indeed two techniques for extracting lithium: in mines, where it is necessary to mix the lithium with water to form a compact paste that will then be filtered to separate it from the rocky debris surrounding it; in aquatic areas, where the water in which the lithium brine bathes is evaporated before, also, filtering it. A ton of lithium requires the evaporation of 2 million liters of water. It is therefore more necessary than ever to discover new lithium extraction techniques, but also other substitutes for these good old lithium-ion batteries.
The occasion to mention a sea serpent: the aluminum-air batteries. Known since the 70s and a patent filed by the US Navy for an aluminum-chloride battery, this process is extremely simple on paper – and at the same time, complex enough not to have yet been deployed on a large scale: a zinc anode (positive electrode) rests in an electrolytic liquid based on water. The air, acting as the negative electrode, produces hydroxyl ions when it comes into contact with the aqueous solution. These oxidize the zinc, thereby releasing electrons captured to power the battery. This technology has many advantages over a classic li-ion. Although polluting, the extraction of aluminum is less so than that of lithium, and it is the third most common metal found on Earth. Moreover, it could be discharged and recharged up to 7500 times without any loss of capacity, while a classic lithium-ion hardly exceeds 1000 cycles, provided that an aluminum anode and a graphite cathode with a non-flammable liquid electrolyte are coupled in a polymer layer. Finally, for an equivalent size, an aluminum battery can store more energy than a li-ion battery – and therefore, have a greater autonomy. According to the work of a former Royal Navy scientist, Trevor Jackson, a battery of volume comparable to those equipping Teslas would allow for a range of 2400 kilometers on a single charge. A French motorist driving an average of nearly 13,000 kilometers a year would only have to “refuel” six times.
If Jackson says he has achieved this result, it is because he has found the solution to one of the major flaws of the aluminum-ion battery: the power delivered has long been too low to power anything larger than a radio – unless the size of the module is increased. And this, because of the formation of a “gel” from the anode/cathode chemical reaction, which prevents all the electrolytes from reaching the cell. A “secret recipe” that he keeps carefully while he has been trying since the early 2000s to raise funds for his company Metalectrique.
A PENDING SOLUTION.
hy then does a process that seems so revolutionary remain doomed to not become more than a small startup registered in France following funding refusals from the British Government in 2005? And this, while the Russian company Rusal produces aluminum emitting no CO2 during its fusion – optimal for this kind of battery – and various other structures – like the Israeli startup Phinergy – are trying to add their piece to the edifice? It can be assumed that the predominance of lithium-ion batteries, whose efficiency has been proven since the release of the first Tesla in 2008, has something to do with it, especially since the issues raised at the beginning of this article are rather recent. Li-ions are at the center of all innovations, all research programs, and all the attention of manufacturers. The entire ecosystem is moreover planned for this motorization which requires a simple recharge, and thus the construction of charging stations, where the alu-ion demands changing the entire battery when it is empty. Which, according to Jackson, would require “only a few seconds.” Only Lotus and Nissan, with its Beyond Lithium Technology program, have briefly been tempted by Trevor Jackson’s research. Perhaps the lithium shortages announced in the coming decades will allow his process to take off? Nothing is less certain.
