Operando optical tracking of single-particle ion dynamics and phase transitions in battery electrodes

Abstract

Key to advancing lithium-ion battery technology, and in particular fast charging capabilities, is our ability to follow and understand the dynamic processes occurring in operating materials under realistic conditions, in real time, and on the nano- to meso-scale. Currently, operando imaging of lithium-ion dynamics requires sophisticated synchrotron X-ray or electron microscopy techniques, which do not lend themselves to high-throughput material screening. This limits rapid and rational materials improvements. Here we introduce a simple lab-based, optical interferometric scattering microscope to resolve nanoscopic lithium-ion dynamics in battery materials and apply it to follow the repeated cycling of the archetypical cathode material Li${}_{\text{x}}$CoO${}_2$. The method allows us to visualise directly the insulator-metal, solid solution and lithium ordering phase transitions in this material. We determine rates of lithium insertion and removal at the single-particle level and identify different mechanisms that occur on charge vs. discharge. Finally, we capture the dynamic formation of domain boundaries between different crystal orientations associated with the monoclinic lattice distortion at around Li${}_{0.5}$CoO${}_2$. The high throughput nature of our methodology allows many particles to be sampled across the entire electrode and, moving forward, will enable exploration of the role of dislocations, morphologies and cycling rate on battery degradation. The generality of our imaging concept means that it can be applied to study any battery electrode, and more broadly, systems where the transport of ions is associated with electronic or structural changes, including nanoionic films, ionic conducting polymers, photocatalytic materials and memristors.

18 pages, including 5 figures

References in corpus (10)

• Theory of Chemical Kinetics and Charge Transfer based on Nonequilibrium Thermodynamics
• Nucleation of dislocations and their dynamics in layered oxides cathode materials during battery charging
• Direct optical sensing of single unlabeled small proteins and super-resolution microscopy of their binding sites
• Nanoscale Imaging of Lithium Ion Distribution During In Situ Operation of Battery Electrode and Electrolyte
• Li diffusion in Li${}_x$CoO${}_2$ probed by muon-spin spectroscopy
• Imaging material functionality through 3D nanoscale tracking of energy flow
• Three dimensional localization of nanoscale battery reactions using soft X-ray tomography
• The point spread function in interferometric scattering microscopy (iSCAT). I. Aberrations in defocusing and axial localization
• Ultrafast Tracking of Exciton and Charge Carrier Transport in Optoelectronic Materials on the Nanometer Scale
• Electric-Double-Layer-Modulation Microscopy

Cited by in corpus (8)

• Operando monitoring of single-particle kinetic state-of-charge heterogeneities and cracking in high-rate Li-ion anodes
• Emerging Optical Microscopy Techniques for Electrochemistry
• Interplay between Phase Transformation Instabilities and Spatiotemporal Reaction Heterogeneities in Particulate Intercalation Electrodes
• Operando Label-free Optical Imaging of Solution-Phase Ion Transport and Electrochemistry
• In-plane staging in lithium-ion intercalation of bilayer graphene
• The importance of electronic correlations in exploring the exotic phase diagram of layered Li${}_x$MnO${}_2$
• Atomistic origins of asymmetric charge-discharge kinetics in off-stoichiometric LiNiO${}_2$
• Computing the Local Ion Concentration Variations for Electric-Double-Layer-Modulation Microscopy