Half an hour’s drive from the city of Reno, in the US state of Nevada, the building that could define the next decade of technology begins to take shape. It is a two-story metal structure raised above the desert that today is easy to confuse with the skeleton of any shopping center in the American suburbs. But appearances can be deceiving. Next year, this facility, costing approximately $ 5 billion, will become the largest battery factory in the world . In 2020, when it reaches its maximum production capacity, it will be able to create half a million a year; Enough to store about 35 gigawatt-hours of energy (one gigawatt equals one billion watts).
That enormous power will be reflected in his name. Baptized as Gigafactory 1, it will be the first lithium battery factory of the electric car company Tesla, which builds it together with the Japanese industrial giant Panasonic to find a solution to the biggest problem facing the world of technology and that, by extension, it is also one of the headaches of the automotive industry. After 25 years on the market, lithium-ion batteries have been refined and perfected to the maximum, but they do not give more of themselves .
Without a commercially viable alternative, Tesla’s only way out is to increase battery production to meet the demand of a growing fleet of electric vehicles. This will also be the key to reducing the price of these devices. Gigafactory 1 will have a production capacity equivalent to that of the world in 2013 , and it will not be Tesla’s only battery factory. Thanks to them, the company will be able to put cheaper cars on the market than those it offers now.
Beyond lithium ions
Whoever sees in this strategy more of a patch than a solution is not wrong . The race to find a substitute capable of storing more energy and doing so more safely than current lithium-ion batteries has intensified in recent years, but at the moment there is no clear winner. “If what we are looking for is a new technology capable of changing the world, of taking a significant leap in capacity, the truth is that we have not yet achieved it. Almost everything that we have improved in the autonomy of electronic devices is due to greater efficiency in the processors and screens, ”says Kazuo Hirai, president of Sony, the pioneer in the sale of lithium-ion batteries.
In essence, a battery is a device made up of positive and negative electrodes and a liquid electrolyte that stores electrical energy through a chemical reaction. The idea for this technology was presented to the Royal Society of London in March 1800 by the Italian physicist Alessandro Volta , but only as a theoretical device. It took sixty years for the French scientist Gaston Planté to build the first battery, which took advantage of the reaction of sulfuric acid with lead . This interaction is so convenient and easy to control that it continues to be the basis of the batteries we use in most cars, those responsible for powering the engine starter, the radio or the lights.
The study of the different applications of electric current in the second half of the nineteenth and early twentieth centuries led to the development of novel battery designs, with greater storage capacity or more desirable properties. In 1899, the Swedish scientist Waldemar Jungner created the first nickel-cadmium battery, for example; and in 1955 Lewis Urry came up with the formula for today’s alkaline batteries .
Due to its low density and ease of transferring electrons, lithium soon became one of the most promising candidates for these instruments. The first experimental developments occurred in the second decade of the 20th century, but the two great wars and the triumph of the internal combustion engine diverted the attention of the scientific community.
The energy crisis of the 1970s rekindled interest in this material : at the beginning of that decade, Michael Stanley Whittingham, a researcher at the oil company Exxon, created the first lithium-ion battery. The battery used as one of the electrodes titanium sulfate, a very expensive material whose reaction was also very unstable, which led to its commercial application being ruled out.
The miracle that made the commercial development of lithium batteries possible came about thanks to the American physicist John B. Goodenough, who at the age of 92 is still a professor at the University of Texas. “I don’t want to leave this world without having designed a better drum set, and at my age I still want to,” he said in a recent interview.
A cool cathode
Goodenough developed a cathode – the positive electrode – based on a lithium cobalt oxide compound that made it possible for the first time to manufacture stable and safe batteries. Since then, and except for minor adjustments, this cathode has been used in practically all devices: it is found in our mobiles, our laptops, our cameras or our portable music players.
With a stable cathode, the challenge for the scientific community became the formulation of the anode, the negative electrode. The Moroccan scientist Rachid Yazami discovered in the 1980s that graphite was especially effective, and with these two materials the Japanese company Asahi Chemical created the first commercial battery, which Sony began to distribute in 1991 .
Although we despair of the continuous need to charge our phones and computers, the truth is that battery technology advances every year . Generally, manufacturers are able to scratch 2% to 5% more charge for the same volume and weight thanks to small adjustments in the formulation or design of the cathode, anode or the use of different electrolytes. And they have also made it possible to recharge them, at least partially, at a higher speed; a very useful trick when we run out of power in the mobile phone and we can only plug it in for a few minutes at the bar or some charging point.
These advances, however, are not significant or the revolution that we all want. They allow to maintain an autonomy more or less similar to that of previous generations of products, but they carry with them some of the problems that have made it difficult to use these batteries in the last three decades: lithium-ion batteries degrade over time . They have a limited life that is measured in recharge cycles and is responsible for making a three-year-old phone cost a world to store energy for a whole day.
There is another problem: the electrolyte used in many of them is liquid and highly flammable . He is responsible for periodically watching videos in which a laptop or other device spontaneously burns, in principle for no apparent reason. A short circuit, an overheating or a small rupture in one of the internal membranes is enough to make the flames jump. Hence, the airlines prohibit the transport of these batteries in the warehouse, where an accidental fire would be difficult to detect in time.
And the biggest drawback of all remains: storage capacity . A lithium-ion battery provides about 160 watt-hours for every kilogram of weight. The most advanced batteries on the market exceed 250 watt-hours per kilo, but they are not cheap. If we want to eliminate the feeling of anxiety when driving an electric car, the batteries of the future should be able to store much more energy inside them, about 350 watt-hours per kilogram, at the very least . If not, the only alternative is to put more batteries and increase both the weight of the vehicle and its cost or recharging time.
As a starting point, lithium is still the most interesting material to achieve this leap in quality . For this reason, the efforts of the laboratories are focused on three areas: improving anode technology; do the same with the cathode; and to achieve a more efficient electrolyte and, if possible, solid, thus increasing the safety and capacity of the devices.
For the anode, the greatest promise is the use of silicon structures instead of graphite. Silicon absorbs up to ten times more lithium ions per gram than graphite during the charging process, but the problem is that higher absorption also implies expansion. It swells like a sponge to three times its size, with disastrous consequences for the internal structure of the battery .
At Stanford University, in California, they are testing the use of silicon nanostructures capable of expanding in a controlled way that could be a viable alternative, but to reach a commercial phase still requires years of research.
Another alternative is to replace the graphite of the anode with graphene, that miraculous material made of pure carbon that is on the lips of the entire scientific community . An anode built with several layers of graphene one atom thick would absorb a greater amount of ions and would make it possible to create batteries with more than twice the capacity for the same weight. This anode, however, would inherit some of the drawbacks that batteries with graphite anodes have today. During the charging process, carbon does not behave like an ideal material . It is common for lithium ions not to completely cover the available surface, especially when trying to recharge at high speed. Instead, they tend to branch out from certain points and can grow to touch the cathode, ruining the battery. To avoid this, internal porous membranes are used, but these branches can clog some of the pores and shorten the life of the device .
The cathode is the element in which innovation is reaping the best results. Through the use of nanomaterials, several laboratories have managed to make it remarkably more efficient by shortening the distance that ions must travel, thus accelerating the rate of charge.
But the biggest change for the batteries of the future would be the creation of a new electrolyte . The transition from a liquid to a solid would make them safer and allow the use of a lithium metal anode or other metallic compounds. With them, their capacity would increase significantly and they could be recharged in much less time. Some companies have started to manufacture these solid state batteries, and even small commercial trials are underway, for example in the automotive sector.
BlueIndy, a car rental company for the streets of Paris, integrates these solid-state batteries into their cars, which are still very expensive to manufacture and have drawbacks. So far, no solid material has shown the same effectiveness as a liquid electrolyte in conducting ions , and some solids fail with changes in temperatures.
In search of sustainability
One of the most promising avenues of research focuses on ceramic materials . The University of Maryland has created a high-conductivity one that would allow for lighter and more efficient batteries. Eric Wachsman, professor of Engineering at that center, affirms that “these batteries are safer and will meet the requirements demanded by the transition from internal combustion vehicles to electric vehicles, or those of extending the autonomy of our devices.” The project has convinced NASA, among others, that it sees this type of device as the solution for storing energy in its future space missions .
Better batteries, with greater capacity and shorter charging times, will revolutionize transportation and consumer electronics, but their greatest impact could be in the field of renewable energies, which are increasingly present all over the planet thanks to the constant cheapening of cells. photovoltaic and wind generators.
In Spain, renewables could cover more than a third of the annual electricity demand . In addition, there are periods of the day and certain seasons of the year in which they would be able to supply the entire population. The problem is that wind generators and solar panels produce electricity intermittently and contribute to the electricity grid in periods of low demand.
We tend to consume more energy at night, when we need artificial light and come home from work. At that time, we are forced to use a network that is still powered by power plants that run on hydrocarbons or nuclear energy. Batteries capable of charging and discharging at high speed and with high energy density could fill the deficiencies of the system and store electricity during the day to consume it at night.
