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Solid oxide fuel cell; The future of electric mobility?

While it is true that very competitive models of electric cars are appearing, for electric mobility to become a reality, the autonomy offered by electric vehicles should be even greater.

Precisely innovation in battery development will be key in the popularization of electric cars. This is a goal that the European Union is pursuing on its agenda to meet its decarbonisation targets by 2050. Several reports estimate that, from 2030 onwards, this type of car should only be sold in the EU. be able to limit global warming 1.5 ºC.

The cost of electric car batteries is a third of the final price of the vehicle and, in addition, the current ones are unstable, lose properties over time and are difficult to recycle.

The evolution of batteries has gone in two directions: increase their capacity and do so by trying to contain as much as possible their weight to optimize energy use. A development that, in the case of electric car batteries, has a name: lithium ions. In fact, it is the predominant technology in these cars, although there is already talk of solid state batteries, which could provide even more autonomy and significantly shorter charging times.

In fact, the latter are an evolution of the former, which use a technology that leaves us almost no room to continue developing their benefits. Lithium is still the central chemical element in the batteries it proposes, but, unlike the lithium-ion batteries we use massively today, it uses a solid-state electrode, not a liquid-state, conductive matter between the 'anode or positive pole and the cathode or negative pole is a solid matter. At first it may not seem like much, but this change triggers huge advantages that, on paper, will make a difference in the battery market.

Current lithium ion batteries

On the one hand, the lithium-ion battery consists of two electrodes; the cathode and the anode, which are divided by a separator, integrated into a cell and immersed in the electrolyte, a conductive liquid that chemically reacts the necessary ions between the electrodes. And the combination of multiple cells forms the battery.

Well, when we start our vehicle these chemical reactions are activated that trigger the circulation of ions between electrodes, thus producing electrons, being transferred to the battery terminals and generating energy. And when we recharge the battery, the particles circulate in the opposite direction and the reverse effect occurs.

As we know, these batteries have a limited life of between 8 and 10 years, which is equivalent to about 3,000 full charge cycles. This is because lithium ion batteries, over time, ie with life cycles (charging and discharging), the liquid lithium solidifies by eating the separator between the anode and cathode creating dendrites. . These dendrites will cause a drop in battery performance and in extreme cases cause overheating, a short circuit and even an explosion.

Compared to traditional lithium batteries, the difference between solid lithium battery lies in the solid electrolyte, which has some advantages in theory

- High safety performance: The liquid electrolyte contains a flammable organic solution, it is easy to burn and explode when the temperature of the short circuit rises sharply, so it is necessary to install the structure of the anti-temperature rise safety device and anti-short circuit. And the solid electrolyte is non-flammable, non-corrosive, non-volatile, no leakage problem, it also overcomes the lithium dendrite problem, so the solid state battery has a very high safety.

- High energy density Using a solid compound in the cells allows you to have a higher energy density, which translates into a greater capacity for energy storage. These types of batteries would be able to store up to three and even five times more energy than their equivalent lithium-ion batteries. Therefore, this means that they allow much higher autonomy.

- The mass is relatively light: The central point is that it is not necessary to use negative graphite electrodes interspersed with lithium, but to use lithium metal directly as a negative electrode, which can significantly reduce the material of negative electrodes. amount of power can significantly increase the energy density of the entire battery.

The second advantage is thin. In traditional lithium ion batteries separators and electrolytes are required, which together account for almost 40% of the battery volume and 25% of its mass. And if they are replaced by solid electrolytes (mainly organic and inorganic ceramic materials), the distance between the positive and negative electrodes (traditionally full of diaphragm electrolyte, now full of solid electrolytes) can be shortened to a few times a dozen. of micrometers, so that the thickness of the battery can be greatly reduced, so that all-solid-state battery technology is the only way to miniaturize and thin batteries.

- Good cycle performance The solid electrolyte solves the problem of the solid electrolyte interface film formed by liquid electrolytes during charging and discharging and the phenomenon of lithium dendrite, which greatly improves the circularity and the life of lithium batteries. They also reduce passive drainage (discharging the battery when not in use).

- Cheaper cost price - price reduction By replacing the liquid, volatile, flammable and corrosive electrolyte with a plastic polymer that can operate at room temperature, production costs are reduced. It allows you to do without many of the security systems required by current batteries, thus lowering costs.

The cooling system and liquid containment system are also removed, which simplifies the design of the cells, modules and the complete battery pack. This simplicity facilitates the automation of the production process so that all cells can be manufactured on a commercial scale

The future of this technology?

An MIT study is also working on the design of a metal anode made of pure lithium.

More than one manufacturer has already begun to opt for this type of technology and even in developing its own patent, such as John B. Goodenough and Samsung. Toyota, Porsche, BMW, Fisker, Hyundai, General Motors, Honda, Nissan, Daimler and Volkswagen are examples of brands that are already investing in their development.

A Taiwanese battery manufacturer announced in a contest an agreement with different car manufacturers to install the new high-voltage solid state batteries with ceramic electrolyte (based on the MAB technique, Multi Axis BiPolar +) in their cars electric

Some point out that the future of the solid state battery will be using silicon instead of glass, others that the most promising is to use sodium-based glass (salt), to be a very common material on earth and low environmental impact.

Solid electrolyte is one of the future directions of battery technology. Although there is still a long way to go in terms of electrolyte materials, cost and technology, more companies in the battery industry will surely invest in it in the face of its huge space of commercial value. With the development of technology, the pace of industrialization of solid state batteries will be closer to us.

Solid state batteries are the latest generation battery technology that is closest to commercial applications, and will provide new explosions and key technical guarantees for the new energy industry in the future.