MIT research team with cooperation of Samsung Advanced Institute of Technology have developed a new material (solid electrolyte) for a basic battery component that they say will enable almost indefinite power storage and will make lithium-ion batteries much safer.
8/27/15 5:00 am chumakdenis 1
MIT and Samsung scientists have succeeded in making significant breakthroughs that can give lithium-ion batteries almost indefinite lifetimes and quadruple the amount of energy these batteries can store.
Additionally, their development can make lithium-ion batteries inflammable.
Well, let’s figure it out.
One of the three basic components in batteries is the electrolyte, and at the moment, most rechargeable batteries contain a liquid electrolyte, which is flammable and responsible for the overheating.Hence, researchers from MIT and Samsung decided to develop a solid electrolyte instead.
They have developed a solid lithium-ion conductor made from a compound of lithium, germanium, phosphorus and sulfur that was a workable solid-state electrolyte.
Not only is the solid-state electrolyte safer since it isn't flammable, but it also lasts much longer than a conventional battery as it has no degradation reactions left. This means that the batteries would survive being used, recharged and used again for hundreds of thousands of cycles.
“With a solid electrolyte there’s no safety problem: you could throw it against the wall, drive a nail through it or do other stuff alike. There’s simply nothing there to burn” - said Gerbrand Ceder, a professor of materials science and engineering at MIT and one of the main researchers.
Batteries that included the solid-state electrolyte were able to perform even at extremely cold temperatures of -20 degrees Fahrenheit, which isn't possible in the batteries of today.
More details on that you can read in the research, entitled Design principles for solid-state lithium superionic conductors published in the journal Nature Materials.
Power density improvement
The solid-state electrolyte also allows for greater power density - the amount of power that can be stored in a given amount of space. Such batteries provide a 20 to 30 percent improvement in power density - with a corresponding increase in how long a battery of a given size could power a phone, a computer, or a vehicle.
As it turns out, forgetting about something is not always a bad thing: MIT and Tsinghua University scientists accidentally discovered that they could quadruple the amount of storage available in a lithium-ion battery after leaving an experiment running for too long.
Over time, lithium-ion rechargeable batteries begin to decline in performance as lithium compounds build up on the electrodes as they charge and discharge. This exposes the electrodes which eventually decompose.
A solution would be to replace the graphite anodes being used today with aluminum.However, oxide forms immediately on the surface of aluminum nanoparticles as soon as they are exposed to air.
Thus, Dr Wang Changan of Tsinghua University and Dr Li Ju of MIT decided to soak aluminum nanoparticles in a mix of sulphuric acid and titanium oxysulphate in order to remove aluminum oxide and replace it with a new outer coating of titanium oxide.
Nevertheless, they forgot about one batch of nanoparticles and left it to soak for so long that the mixture soaked into the aluminum nanoparticles. The nanoparticles were originally 50nm of aluminum, but after being soaked, the nanoparticle then had an inner "yolk" of only 30nm of aluminum, while the shell that covered it was 4nm of titanium hydroxide.
The scientists decided to use these new nanoparticles to build batteries, and they created a battery that was able to retain four times the amount of energy that current batteries are able to store, as well as lengthening the battery's lifespan by over 500 use and recharge cycles.
Their paper, entitled "High-rate aluminium yolk-shell nanoparticle anode for Li-ion battery with long cycle life and ultrahigh capacity" is published in the journal Nature Communications.
“The team has a long, outstanding track record in computational materials science, and they succeeded again in providing the battery and materials communities new scientific insights to push the fields forward.”
Meng adds that this study provides some very significant design principles for designing and optimizing new solid state electrode (SSE) materials. Now the experimentalists can explore the new phase space with this guidance and speed up SSE discovery. It is very exciting.
Let's wish them good luck with that and wait for more news from them.