Operando optical tracking of single-particle ion dynamics in batteries

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 mesoscale. 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 LixCoO2. 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 Li0.5CoO2. 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.Lithium-ion batteries have emerged as the frontrunner technology to achieve highpower, intermediate-scale energy storage, with a broad range of applications including electric

Influence of Temperature and Electrolyte Composition on the Performance of Lithium Metal Anodes

“…Another method for investigating lithium deposition during cycling is insitu observation using special cell holders. Insitu observations in the ECC-Opto Stud, manufactured by EL-Cells GmbH (Hamburg, Germany), on battery cells were made in [26][27][28][29][30][31][32][33] using Raman spectroscopy, X-ray diffraction (XRD) and optical analytics. Observations were made using Raman spectroscopy [27,31,32] and XRD [26,28,33] to observe changes in electrodes and SEI during aging.…”

“…Observations were made using Raman spectroscopy [27,31,32] and XRD [26,28,33] to observe changes in electrodes and SEI during aging. Merryweather et al [29] used the above-mentioned cell housing for optical interferometric scattering measurements to detect single-particle ion dynamics, and Rittweger et al [30] observed the reflectivity of cathodes during charge and discharge.…”

Long-chain fluorocarbon-driven hybrid solid polymer electrolyte for lithium metal batteries

“…The urgent demand for high-performance energy storage devices has triggered a new upsurge in research on high-energy-density lithium-ion batteries. 1–3 Nevertheless, due to the potential safety hazards and low theoretical energy densities of conventional lithium-ion batteries consisting of flammable liquid electrolyte (LE) and graphite anodes, researchers have begun to pursue superior alternatives. 4–6 Combining a non-volatile and non-inflammable solid electrolyte with Li metal anodes that have high capacity and low electrochemical potential provides a feasible solution.…”

Current‐Corrected Cycling Strategies for True Electrode Performance Measurement

“…[4][5][6][7] One of the most common strategies to investigate electrode performance is the utilization of galvanostatic cycling. [8][9][10] In each charge/discharge step, a constant current is applied until a designed potential is reached. The C-rate is widely used to describe the discharge/ charge rate and is defined as the current at which a cell can be fully charged or discharged in one hour.…”