Visualization of inhomogeneous current distribution on ZrO2-coated LiCoO2 thin-film electrodes using scanning electrochemical cell microscopy.

Cathode surface coating with metal-oxide thin layers has been intensively studied to improve the cycle durability of lithium-ion batteries. A comprehensive understanding of the metal-oxide morphology and the local electrochemical properties is essential for figuring out the metal-oxide coating effect. In this study, scanning electrochemical cell microscopy (SECCM) is used to analyze the surface morphology with high spatial resolution, together with the local electrochemical properties.

Nanoscale visualization of redox activity at lithium-ion battery cathodes.

Intercalation and deintercalation of lithium ions at electrode surfaces are central to the operation of lithium-ion batteries. Yet, on the most important composite cathode surfaces, this is a rather complex process involving spatially heterogeneous reactions that have proved difficult to resolve with existing techniques. Here we report a scanning electrochemical cell microscope based approach to define a mobile electrochemical cell that is used to quantitatively visualize electrochemical phenomena at the battery cathode material LiFePO4, with resolution of ~100 nm. The technique measures electrode topography and different electrochemical properties simultaneously, and the information can be combined with complementary microscopic techniques to reveal new perspectives on structure and activity. These electrodes exhibit highly spatially heterogeneous electrochemistry at the nanoscale, both within secondary particles and at individual primary nanoparticles, which is highly dependent on the local structure and composition.