The search for the ideal battery continues. Lithium-based solutions have taken us very far, but experts are convinced there are many aspects to improve, including safety and charging time. This brings us to the University of Texas at Austin, where a group of researchers developed a new semiliquid battery with charge and discharge parameters similar to a supercapacitor, and an energy density that is on its way to competing with that of lithium.
What do we want from a battery?
Take a moment to look at your mobile device or laptop. Consider the rechargeable battery in each. What do you want from that battery? I imagine the first requirement is "that it lasts". Lithium-ion batteries have shown an almost supernatural ability to run out of energy at the worst moments, and despite all advances, the average user still carries a charger everywhere...
...which brings us to the second requirement: "that it charges quickly". Personally, I have to wait two or three hours for my old Galaxy Ace to fill its extended battery, assuming it is completely empty. The concept of "opportunistic charging", that is, plugging it in whenever possible, should reduce waiting times and keep the battery at acceptable levels... but the truth is that nobody wants to wait.
On the other side, we have the supercapacitor, with complete charges and discharges that take just a few seconds.
A semiliquid battery
Developing the perfect hybrid between the battery and the supercapacitor should solve almost all our energy problems, and that is where this new announcement by researchers at the University of Texas at Austin gains relevance. It is a "semiliquid battery", based on a solid lithium anode, a liquid cathode, and an electrolyte formed with ferrocene, the same compound that replaced tetraethyl lead as an antiknock additive in traditional fuel. According to chemist Guihua Yu, leader of the research team, the battery has exhibited excellent parameters so far, with a charge and discharge time of under one minute, and an energy density of 40 watt-hours per liter (Wh/L), still far from lithium but close to lead-acid batteries.
Another very interesting and critical aspect is that it managed to retain 80 percent of its capacity after 500 recharges, even with such short and fast cycles. However, the weak point of the battery is none other than the lithium anode. Its presence affects both stability and overall safety, and it will be necessary to develop more advanced protection methods to block any possibility of a "spontaneous discharge", or directly study replacing lithium with another element, such as zinc or magnesium. The next steps will include tests under real usage conditions, and increasing the solubility of ferrocene, which will allow raising the energy density.
