Will lithium-sulfur batteries be in our future?

Monash University Associate Professor Matthew Hill, Dr. Mahdokht Shaibani, and Professor Mainak Majumder with the lithium-sulphur battery design. (credit: Monash University)

The name "lithium-ion battery" seems to imply that lithium is the essential ingredient that dictates the battery's performance characteristics. But that's less true than it appears. The electrodes that the lithium shuttles between are critical for dictating a battery's performance, which is why electrode materials played such a large role in the description of last year's Chemistry Nobel. Different electrode materials dictate the battery's performance in part based on dictating the energy difference between the charged and uncharged state. But they also determine how much lithium can be stored at an electrode, and through that the energy density of a battery.

There are a number of ideas floating around for new electrode materials that store lithium in fundamentally different ways: as solid lithium metal or as lithium oxide, which allows some of the electrode material to come from the air outside the battery. There are also chemicals that can store much more lithium per given area of volume. All of these options present serious issues (often more than one) that have kept them from being adopted so far. But a recent paper is promising a major breakthrough in something that has always been an attractive option for lithium storage: sulfur.

Alternate electrodes

"Holds lots of lithium" isn't a high bar to clear; if that was all we were looking for, some of these alternative electrode materials would be in use already. But there's a whole host of other characteristics: cheap and easy to work with, compatible with the chemistry of the rest of the battery components, holds up to repeated charge cycles, and so on.

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