Our lives require storage of electrical energy more than ever these days. Batteries are increasingly finding their way into uses where their weight and safety are of considerable concern. As big car manufacturers try to make waves in the electric vehicle (EV) market (see our blog A supercharged day for Tesla and battery tech), they don’t want to compromise on the reliability, or safety of the vehicles that they sell.
Li-ion batteries, our two-faced friend
Traditional Li-ion batteries contain an electrolyte which is generally made up of lithium salts dissolved in organic solvents (see our blog Lithium-ion batteries - powering the EVs of the future). This technology has powered us into the modern day, however it does come with drawbacks. One disadvantage that occupies EV manufacturers is that when damaged, a Li-ion battery can short-circuit causing uncontrolled release of the energy stored within. This results in rapid heating of the cell which can ignite the highly flammable organic electrolyte. For an EV which contains a very large number of cells, a mass short-circuit event caused, for example, by a car crash can lead to a massive explosion.
Previous efforts to address this safety issue have considered the use of non-flammable electrolytes. Yet these attempts have often suffered from discharge voltages of less than 2 V, low energy density, or poor battery lifetime.
Non-flammable graphene batteries
Earlier this year Nanotech Energy Inc., a company based in Los Angeles, announced the release of a non-flammable battery along with the opening of a series C funding round. Their batteries utilise a combination of graphene electrodes and a specially developed non-flammable electrolyte. Impressively, Nanotech’s batteries appear to overcome many of the issues faced by non-flammable electrolytes. They are reported to discharge at a voltage of around 3.8 V, which is sufficient to power many consumer goods; have an energy density that rivals the best Li-ion batteries on the market; and can maintain at least 80% capacity over more than 1400 cycles, a seriously impressive level of durability.
A key feature of the technology is that the strength and flexibility of graphene allows the electrodes to withstand rapid changes in volume (see our blog Battery electrolytes: the latest graphene composites). Additionally, the non-flammable electrolyte can operate at higher temperatures than traditional electrolytes. This blend of characteristics paves the way for extremely rapid charging. Nanotech have fast charging keenly in their sights setting a goal of releasing a battery than can charge 18 times faster than any currently available batteries within the next year. Batteries that can charge as fast as filling of a tank of fuel will be a significant development for the future success of EVs (see our blog Extreme fast charging – the future of electric vehicle batteries).
Outlook
Andreas Hintennach, Ph.D., global head of battery research for Daimler AG, said of the Nanotech Energy batteries “Usually you sacrifice performance once you develop extremely safe chemistry. Now, for the first time, we have access to extremely safe chemistry that provides high performance and we are very pleased”.
Clearly the potential impact of this new technology has generated interest from the business world. Nanotech’s funding round was oversubscribed and closed at $27.5 million raising 10% more cash than their initial funding target.
The question that remains then, is will these non-flammable batteries live up to their “pyrodigm” shifting expectation?
