Lab-based observations offer insights into battery performance

Currently, visualising active battery materials requires synchrotron X-ray or electron microscopy techniques, which can be difficult and expensive, and often cannot image quickly enough to capture the changes occurring in fast-charging electrode materials. Consequently, the ion dynamics on the length scale of individual active particles and at commercially relevant fast-charging rates remains largely unexplored.

In their work, which is detailed in Nature Materials, the researchers sent visible light into the battery through a small glass window, which allowed them to watch the dynamic process within the active particles of a niobium tungsten oxide in real time, under realistic non-equilibrium conditions. Nb₁₄W₃O_­44 is regarded as among the fastest charging anode materials available.

This revealed front-like lithium-concentration gradients moving through the individual active particles, resulting in internal strain which caused some particles to fracture. Particle fracture is a problem for batteries, since it can lead to electrical disconnection of the fragments, reducing the storage capacity of the battery.