In cars with a thermal engine, the technological importance comes from the propellant and the fuel tank happens to be just that, a tank. However, in cars with an electric motor, the opposite happens; both the architecture and the operation of an electric motor is very simple and the greatest technical complexity falls on the battery.
When in 1996 the commercialization of the Fiat Seicento Elettra It was sold as an ecological utility capable of reaching a maximum speed of one hundred kilometers per hour. Had one autonomy of approximately one hundred kilometers and its battery took about eight hours to charge. By the way, due to the size of the battery, this utility vehicle only had two seats and, due to the price, its commercial diffusion was not a great success.
If we go back to the present, a current concept vehicle similar to this Fiat may be the Smart fortwo electric drive. This small utility vehicle has an autonomy that in real use is more or less similar to that of the small Italian and its charging period is also more or less similar, but beware, only if we connect it to a socket of the basic network of a home . The technical advances applied to the battery have allowed the Daimler group brand to offer the possibility of installing specific chargers (WallBox) capable of charging the eighty percent of the battery in just over forty-five minutes.
Basic concept of a battery
the battery just accumulates the electricity that will later be consumed by the electric motor. Its purpose is similar to that of a fuel tank, but its architecture and operation could not be more complex.
Without wanting to go into depth in definitions and/or chemical processes, the operation of a battery is based on the production of electrons from controlled chemical reactions. I imagine that many of you still remember the periodic table, the number of electrons in the last shell and the stability of the chemical compounds formed after a reaction. Well, in the case of a battery, the chemical reaction that occurs inside favors a transfer of electrons from the negative pole to the positive pole.
A battery can be made up of a variable number of cells, small receptacles in which the electrodes are immersed in the electrolyte.
- Electrode: electrical current conductor that is in contact with the electrolyte and with the outside of the cell. It can be positive sign (anode) or negative sign (cathode).
- Electrolyte: any substance that can be broken down by the action of an electric current (electrolysis).
To give a very simple example, in a classic lead-acid battery, one electrode is made of pure lead (Pb), the other of lead dioxide (PbO2) and the electrolyte is sulfuric acid (H2SO4) dissolved in water (H2O).
The set of these cells receive the name of battery precisely because of the necessary association of the cells to produce electrical energy. This association can be in series (negative pole of one cell with the positive of the next cell) to obtain a greater electrical voltage or in parallel (all poles of the same sign joined together) to obtain a greater intensity.
Lithium ion battery
The Smart named above has a lithium ion battery. This means that this battery replaces the sulfuric acid electrolyte with another that is a lithium salt, but the chemical principle that allows it to accumulate electricity is the same.
As far as its application to electric cars is concerned, lithium-ion batteries they have a lower weight and allow a greater number of recharge cycles before a significant loss of capacity occurs, known as battery degradation. Right now it is estimated that a lithium ion battery can retain eighty percent of its capacity even after three thousand full recharge cycles.
Practical drawbacks of the electric car
Leaving aside the price and the few existing adapted infrastructures in our country, the great “problem” of the electric car is its practical analysis. For example, a Volkswagen Golf 1.5 TSI It is a perfect compact for long trips. Your fuel tank allows you to make trips of more than 800 kilometers and we will not spend more than five minutes refueling your tank
If instead we are interested in the new Volkswagen e-Golf, we must be clear that its battery will not allow us to make trips of more than two hundred kilometers and that filling its battery will force us to have a coffee of approximately five hours in a 7 kilowatt outlet.
At this point, more than one will think of a car like the Tesla Model S 100D, with an approved autonomy of 612 kilometres, and the superchargers brand.
In the first place, I recognize that this Tesla is quite a car, but its price of 110.000 euros takes it a little out of the pocket of a large part of the Spanish. On the other hand, in circulation at 60 – 70 kilometers per hour, it is possible to reach the announced autonomy because on trips at 120 kilometers per hour the real autonomy remains at about 450 kilometers, which is not bad either.
Regarding the brand's superchargers, although a great expansion is expected when the commercialization of the Tesla Model 3 begins, today they are mainly focused on the Mediterranean coast. In fact, in Castilla León there are two (Burgos and Valladolid) and in communities such as Cantabria, Asturias, Galicia or Madrid there are not even any.
These superchargers of up to 120 kilowatts allow charge in 20 minutes the electricity needed to do about 300 kilometers but they have a serious drawback: with current technology, such powerful loads shorten battery life.
By this I mean that with current technology and infrastructure, who needs to make frequent long trips should look at plug-in hybrid vehicles. For example, him Volkswagen Golf GTE It can be used on a daily basis as an electric vehicle with a battery that offers about 40 kilometers of autonomy and as a compact 110-kilowatt vehicle that is perfectly valid for long trips. That yes, whenever we travel light of luggage; while the Volkswagen Golf with a gasoline engine has a trunk that offers 380 liters of capacity, that of the hybrid model remains at a discreet 272 liters (341 liters in the fully electric model).
The battery of the future
Nobody escapes the fact that the future of the automotive industry goes through electrification. Currently there are many brands that are committed to the microhybridization of its engines, but this is only an intermediate step between the car powered by fossil fuel and the electric car.
The great bet of the electric car requires a optimization in battery size and performance. On the one hand, it is almost mandatory to offer similar levels of autonomy and charging times that can compete with vehicles equipped with internal combustion engines. On the other hand, it also becomes imperative to reduce the weight of a battery. For example, a Renault Zoe weighs 1.545 kilos and a Renault Clio TCe 66 it stays at 1.082 kilos.
Short term
In a period of four or five years we will already be able to see electric vehicles with a real autonomy of about 600 kilometers thanks to technical improvements applied to the battery.
cars like the Opel Ampera-e they equip one of the most modern batteries that they currently manufacture. Manufactured by LG Chem, the battery in this Opel is made from a combination of cobalt, lithium, manganese and nickel capable of generating enough electricity to move the car for a few 350 kilometers in real conditions of use.
This type of compound battery has a life that doubles that of current lithium ion although it is also true that it weighs approximately ten percent more than the current ones and that the cost of producing them increases by more or less the same percentage.
solid electrolyte battery
Expected for the year 2020, a solid electrolyte has more density than a liquid one and allows this type of battery to store more energy than, for example, a lithium salt battery. Also minimizes the appearance of dendrites, repetitive structures characteristic of the first phases of crystal growth and that can produce short circuits within the battery.
These dendrites, due to their chemical composition, are bodies that may or may not be conductors of electrical energy. For example, ionic and covalent crystals offer a lot of resistance to the conduction of heat and/or electricity, and molecular crystals are totally insulating in this regard. These three types of crystals limit the charging capacity of the battery, since during their formation the electrolyte is destroyed and, therefore, the electrolysis process is limited.
There is a fourth type of crystals, the metallic ones, which are characterized by having few electrons in the outermost layers and being positively charged. This means that in its formation it destroys the electrolyte and also, once the molecule is formed, it absorbs the negatively charged electrons that are stored. This is called chemical stability in the valence shell, which translated means that all molecules tend to have eight electrons (stability) in their last shell (valence shell).
The advantages of solid electrolyte battery is that heats up much less and is less prone to degradation, which means that it is capable of maintaining its storage capacity during many more charging processes.
Graphene in the battery of the future
For years, scientific research programs have given a thousand and one turns to graphene, that material composed of pure carbon arranged in a regular hexagonal pattern which seems to be present in all aspects of our daily lives as long as the current price of 300 US dollars per gram is lowered, of course. Of course, once the price drops, it is expected that graphene will also reach the battery of the electric car.
According to what was experienced in the first prototypes, a graphene battery has a five times the energy density of current lithium batteriesDue to its chemical composition, the risk of explosion is almost nil and in the event of a short circuit, only the damaged part would be inoperative.
Among the advantages of the graphene battery in relation to the current ones is its greater capacity, its lower weight with equal volume and its unsurpassed load capacity (a 100 kwh battery could be charged in less than ten minutes).
Among its disadvantages we can highlight that they would not reach the market before ten or fifteen years and that the only Spanish company dedicated to the investigation of graphene batteries, and which was a world reference, has recently been accused of fraud and is being investigated by the National Securities Market Commission.
When I was little they said that in the year 2000 cars would fly and would not have a driver. I would like to return to this article in the year 2030 and be able to analyze what the current forecasts are. Of course, something tells me that the evolution of batteries will surprise us year after year.