Every once in a while, new technology seems to emerge spontaneously to change our world. Dynamite, penicillin, X-ray machines, and even microwaves are all examples of such new accidental discoveries.
Λοιπόν, φέτος μπορεί να είχαμε άλλη μια. Ωστόσο, αυτή τη φορά δεν πρόκειται μόνο να φέρει την επανάσταση στον τρόπο που ζούμε, αλλά μπορεί να σώσει τον πλανήτη μας από την επικείμενη κλιματική αλλαγή: οι μπαταρίες λιθίου-θείου.
Για δεκαετίες, αναζητούμε την καλύτερη τεχνολογία για να τροφοδοτήσουμε τον σύγχρονο τρόπο ζωής μας και να ενεργοποιήσουμε κάθε νέα τεχνολογία, όπως τα ηλεκτρικά αυτοκίνητα. Από τις αρχές της δεκαετίας του ’90, η τεχνολογία μπαταριών ήταν η ιόντων λιθίου.
They power everything from phones and Teslas to power grid backups and even satellites. But despite the fact that they have happily taken us into the 21st century, they have some serious drawbacks.
First, the materials needed to make them, such as cobalt, are usually very harmful to the environment. They destroy vast ecosystems with toxic chemicals.
Μετά υπάρχει το πρόβλημα του κύκλου ζωής. Απαιτούμε ταχύτερους χρόνους φόρτισης στις συσκευές μας. Αυτό ισχύει για τα πάντα, από τα τηλέφωνα μέχρι τα αυτοκίνητα. Όμως, όπως θα σας πει οποιοσδήποτε διαθέτει smartphone, οι μπαταρίες ιόντων λιθίου χάνουν πολύ γρήγορα την χωρητικότητά τους εάν τις φορτίζετε επανειλημμένα.
Η υποβάθμιση της μπαταρίας είναι ένα πολύ σοβαρό πρόβλημα, ιδιαίτερα για τον κόσμο των EV. Τα μεταχειρισμένα EV μπορεί μερικές φορές να είναι άχρηστα εάν τελειώσει η μπαταρία, κάτι που θα κοστίσει μια μικρή περιουσία για την αντικατάστασή της. Συνολικά, αυτό επιβραδύνει την υιοθέτηση των ηλεκτρικών οχημάτων. Βέβαια αλλαγή μπαταρίας σημαίνει και ηλεκτρονικά απόβλητα, τα οποία είναι ήδη ένα σημαντικό πρόβλημα.
There is also the problem of density. Li-ion packs are relatively energy dense, but still very heavy, large and bulky. This limits the range of electric cars because the batteries are so heavy. This makes the use of batteries impossible for some applications, such as commercial electric airplanes.
There is even the problem of fire with lithium-ion batteries, as a damaged cell can cause a fire which is very difficult to extinguish.
These are the reasons why scientists at Drexel are looking for a new type of battery.
The batteries lithium-sulfur they seem to solve all the problems of lithium ion. They use far less ecologically harmful materials, can be cheaper to produce, can be up to three times more energy dense (which means lighter batteries) and are far less likely to catch fire. All this without any loss in charging speeds.
So what's the problem? Why don't we already have them?
They have a huge problem. While a lithium-ion battery can be used for about 2000 charge cycles, lithium-sulfur batteries are typically limited to half that. So after a year or two of proper use, a lithium-sulfur battery stops working.
To solve this, the Drexel team tried new approaches, changing the compounds in the battery's cathode.
Their goal was to slow down the chemical reaction that creates polysulfides when the battery is charged and discharged. These crystals remove sulfur from the electrode and eventually cause a huge loss of capacity. Slowing it down could make these very energy-dense batteries last longer.
What they found was something incredible: μια χημική φάση θείου που ουσιαστικά σταματά την υποβάθμιση της μπαταρίας! Ήταν τόσο σοκαρισμένοι από αυτή την ανακάλυψη που χρειάστηκε να την ελέγξουν 100 φορές για να βεβαιωθούν.
This chemical phase is also known as the monoclinic gamma-sulfur phase, but it had only been observed in the laboratory at very high temperatures — above 95°C. This was the first time it was observed at room temperature.
In this phase the battery completely stops the reaction that creates polysulphides. This was so efficient that the scientists were able to perform 4.000 charge cycles without a drop in capacity, which means it lasts at least twice as long as lithium-ion batteries.
It's also worth noting that their battery was three times more energy dense than lithium-ion and could charge just as fast!
As with most serendipitous discoveries, scientists have not yet figured out what is actually going on. They don't yet know why this sulfur phase is created or how they can make sure it stays that way. So further research is needed to answer these questions in order to develop a reliable battery that can be used in billions of computers, electric cars and more.
The wait will be worth it as these batteries will weigh a third of their Li-ion counterparts and last twice as long!
Lithium, sulfur, and the other materials needed for this new battery are abundant all over Earth. This means we can drastically minimize the ecological impact of mining, as well as ensure a stronger supply chain.
However, the Drexel team is already looking at using this breakthrough to make sodium-sulfur batteries. By eliminating the need for lithium, they will be able to make batteries even more environmentally friendly and remove a huge bottleneck from the supply chain, ensuring EV adoption can continue at the breakneck speeds automakers plan.
This serendipitous discovery from Drexel will revolutionize the world's energy use and help humanity transition to a cleaner, carbon-neutral society. Hopefully the Drexel team can get this technology out of the lab and into our hands soon.
