10 doubts (resolved) about the battery of an electrician

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Little by little, but already in a race with no return, 100% electric cars are taking their place in the market. Although they are still expensive and with a recharging infrastructure to develop, the increasing autonomy of their batteries is ending up convincing some customers that, we are not going to be fooled, very rarely will they have it as the only car in the house. That, when they are not users of renting vehicles.

This is the case of those supplied by the French company Arval, which has drawn up a decalogue to answer the great questions that exist around the battery, the determining element of this technology. The questions are resolved by Dr. Álvaro Caballero, who leads a research team on cleaner, higher-performance batteries based on lithium and sulfur. It does so at the University of Córdoba, one of the national benchmarks in this technology.

How does a battery work?

A battery simply provides an energy to be used in any electrical device, but this energy has had to be provided previously (in charge). This supplied electricity transforms it into chemical energy within the poles of the battery and releases it when it is not charging and the device needs to function. It would be something like an elevator, when you charge the battery you are going up in the elevator thanks to external electricity, staying in a state of high energy. And when you go down, you take advantage of that energy to give the elevator movement without the need for external electricity.

What metals do they carry inside?

In the most used batteries in electric vehicles (NMC), we can find six metals: cobalt, nickel, manganese, lithium, aluminum and copper. The latter, used in the negative pole, is the one with the highest percentage by weight among these metals, despite the fact that the batteries are known as Li-ion. The seventh basic component of the battery is graphite.

Why do they lose performance over time?

There are two main reasons. The first, the secondary reactions that occur at the battery poles , where the original materials modify their structure and composition. The second, the physical degradation of the electrodes, that is, they crack throughout the cycles and lose connectivity between the components, slowly decreasing the amount of useful material inside the battery, and, consequently, the performance Of the same.

Are there a limited number of life cycles?

The number of life cycles will depend on the quality of the battery components and the minimum performance we need for the vehicle. End of life is considered by a large number of manufacturers to be reached when the battery does not exceed 80% of its original capacity. Reaching this point will depend on the quality of manufacture of the battery and the use in the vehicle. It should be borne in mind that later there is the possibility of giving a second life to this battery in less demanding applications than electric vehicles, such as, for example, in the storage of renewable energy.

Do you have to change them whole or only some cells?

This will depend on the configuration of the battery pack. If they have been assembled in a decoupled way, the battery stacks where faulty performances are detected could be replaced by fresh elements.

Do car batteries have a memory effect?

Batteries based on Li-ion technology, from mobile phones or from electric vehicles, do not have the memory effect so pronounced that was observed with previous battery technologies, such as those based on Nickel.

How to charge them so they last longer?

It is always better to follow the instructions of the supplier, since the battery will work according to some charge and discharge protocols programmed by the manufacturer in the BMS (battery control system). In almost all cases, it is recommended not to download completely, as well as not to recharge up to 100%. Only up to 80%? The battery monitoring system is set up to manage the battery charge in its optimal operating range. When it approaches 80-90%, many of these systems regulate the current to affect as little as possible a possible battery overload.

Does charging with supercharger affect its duration?

The charging system supplied by the manufacturer or assembler of the battery packs is always recommended, as it will be configured for optimal operation. Superchargers are ideal for shortening time, but not all batteries withstand the high currents they supply, causing post-charge performance to be very low.

They are reputed to be toxic, can they be recycled?

Metal components in the battery, such as cobalt or nickel, are not environmentally friendly. For this reason, the collection and recycling of these batteries should be an obligation in the future, a process that was already carried out in its day with lead batteries in vehicles. There are a large number of research groups dedicated to studying how to efficiently recover all battery components after their useful life, and some companies dedicated to this work have already established themselves in Europe. In our group we have already achieved important achievements recovering manganese and graphite from spent batteries.

How is an electric car isolated to make it safe?

The high-voltage system used in the car to move the vehicle could cause electrocution in man, but it is protected with armored boxes that act as a security system. Of course, in an accident, depending on the degree of the accident, if these systems were to be damaged, the current of the high-voltage system would have to be disconnected to avoid electrocution.

What potential for performance evolution do they have?

Current Li-ion batteries have less and less potential for improvement, getting closer to their theoretical capabilities. However, the first important leap in evolution will come thanks to the technology based on Lithium-Sulfur, which will provide at least twice the energy, that is, twice the autonomy of the vehicle or half the weight of the battery. Other alternative technologies such as Lithium-Air or those based on metals more abundant than lithium, such as sodium, potassium or aluminum, still need to carry out in-depth research to reach prototypes outside the laboratory, although in the case of sodium, the prospects have lately been considerably improved.

What about sustainability?

Apart from the performance of the battery, it is also necessary to evolve in safety and sustainability. In the first factor, developing new non-flammable electrolytes. In the second, designing batteries with abundant, non-toxic and low-cost materials, for example, from biomass or industrial or agricultural waste. We cannot go from dependence on oil (diesel or gasoline) to depend on the components of the battery (lithium, cobalt, nickel, ...). It would simply stop exploiting a fossil resource, finite and located at certain points on the planet (oil), and change to other resources with the same characteristics (metals).

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