Shedding light on battery materials

The three most common ways ions assemble at an electrode are within its atomic layers, on its surface, or atop other ions already on its surface. Each of these arrangements has benefits and drawbacks when it comes to performance of energy storage devices such as batteries. Entering into the electrode material’s layers allows more ions — energy — to be stored. Attaching and detaching to the surface of the material enables a quick release of energy. And perching with solvent molecules atop a layer of ions on the surface allows for a slightly larger power discharge but less energy.

Researchers can observe how long and quickly it takes a storage device to discharge and charge again, or test the electrode material at the beginning and end of a discharge cycle, to find out what the predominant storage mechanism is. But recent research suggests that these energy storage mechanisms may not always occur as ordered, separate reactions. There are a number of reactions happening in the device with mixed or intermediate mechanisms. Thus, accurately distinguishing the different mechanisms and fundamentally understanding them is important for improving the performance of energy storage devices.

Being able to precisely keep track of ions within an electrode and track them over the course of its charge-discharge cycles will help researchers to gain a better picture of all the reactions taking place — and, importantly, identify the side reactions that may occur.  Armed with this information, designers could better tailor electrode materials and electrolytes to enhance performance and limit their degradation.