Revealing Local Grain Boundary Chemistry and Correlating it with Local Mass Transport in Mixed-Conducting Perovskite Electrodes.

Grain boundary (GB) mass transport, and chemistry exert a pronounced influence on both the performance and stability of electrodes for solid oxide electrochemical cells. Lanthanum strontium cobalt ferrite (LSCF6428) is applied as a model mixed ionic and electronic conducting (MIEC) perovskite oxide. The cation-vacancy distribution at the GBs is studied at both single and multi-grain scales using high-resolution characterization techniques and computational approaches.

The importance of A-site cation chemistry in superionic halide solid electrolytes.

Halide solid electrolytes do not currently display ionic conductivities suitable for high-power all-solid-state batteries. We explore the model system AZrCl (A = Li, Na, Cu, Ag) to understand the fundamental role that A-site chemistry plays on fast ion transport. Having synthesised the previously unknown AgZrCl we reveal high room temperature ionic conductivities in CuZrCl and AgZrCl of 1 × 10 and 4 × 10 S cm, respectively.

Probing Jahn-Teller Distortions and Antisite Defects in LiNiO with Li NMR Spectroscopy and Density Functional Theory.

The long- and local-range structure and electronic properties of the high-voltage lithium-ion cathode material for Li-ion batteries, LiNiO, remain widely debated, as are the degradation phenomena at high states of delithiation, limiting the more widespread use of this material. In particular, the local structural environment and the role of Jahn-Teller distortions are unclear, as are the interplay of distortions and point defects and their influence on cycling behavior. Here, we use Li NMR measurements in combination with density functional theory (DFT) calculations to examine Jahn-Teller distortions and antisite defects in LiNiO.

Superstructure and Correlated Na Hopping in a Layered Mg-Substituted Sodium Manganate Battery Cathode are Driven by Local Electroneutrality.

In this work, we present a variable-temperature Na NMR and variable-temperature and variable-frequency electron paramagnetic resonance (EPR) analysis of the local structure of a layered P2 Na-ion battery cathode material, Na[MgMn]O (NMMO). For the first time, we elucidate the superstructure in this material by using synchrotron X-ray diffraction and total neutron scattering and show that this superstructure is consistent with NMR and EPR spectra. To complement our experimental data, we carry out calculations of the quadrupolar and hyperfine Na NMR shifts, the Na ion hopping energy barriers, and the EPR -tensors.

Proton-coupled electron transfer at SOFC electrodes.

Understanding the charge transfer processes at solid oxide fuel cell (SOFC) electrodes is critical to designing more efficient and robust materials. Activation losses at SOFC electrodes have been widely attributed to the ambipolar migration of charges at the mixed ionic-electronic conductor-gas interface. Empirical Butler-Volmer kinetics based on the transition state theory is often used to model the current-voltage relationship, where charged particles transfer classically over an energy barrier.