MIT lithium-oxygen battery lasts a long time and is more efficient

MIT has announced a breakthrough in battery technology that might one day mean EVs that can drive further on a charge and gadgets that last longer away from an outlet. For a long time MIT and other research organizations have been looking at lithium-air batteries, but those batteries have some significant drawbacks. While lithium-air promises high-energy output compared to weight, they waste much of the power introduced as heat and performance degrades quickly. The new MIT lithium-oxygen battery overcomes these big drawbacks.

In a normal lithium-air battery a voltage mismatch involved in charging and discharging the batteries causes a power loss in each charging cycle. Researcher Ju Li says that 30% of the electrical energy is wasted as heat in charging. With the new lithium-oxygen battery, the same sort of electrochemical reactions take place between lithium and oxygen during charging and discharging. However, they take place without allowing oxygen to revert to a gaseous form,

The oxygen remains a solid transforming directly between its three redox states. This is done by binding the oxygen in three different solid chemical compounds of Li2O, Li2O2, and LiO2 mixed together in the form of a solid glass. "This means faster charging for cars, as heat removal from the battery pack is less of a safety concern, as well as energy efficiency benefits," according to Li.

The new form of battery is also inherently protected from overcharging according to the design team. This is because the chemical reaction in the battery is self-limiting and when overcharged the reaction shifts to a different form preventing more activity. With a typical battery, if you overcharge it, it can cause irreversible structural damage or even explode," Li says. The team says it overcharged the battery for 15 days, to a hundred times its capacity, with no damage.