Search

We describe the general synthesis of submicrometer-thick rare-earth/lanthanide sesquioxide (RE2O3) films with tailorable pore and grain sizes via polymer templating of hydrated chloride salt precursors. Mesostructured RE2O3(RE = Sm, Tb–Lu) ceramics with cubic pore symmetry and high surface area (SBET≥ 50 m2g–1) were prepared using different diblock copolymer structure-directing agents and were characterized by a combination of electron microscopy, in situ and ex situ grazing incidence small-angle X-ray scattering, N2physisorption, X-ray photoelectron spectroscopy, X-ray diffraction including Rietveld refinement, and ultraviolet–visible spectroscopy. In the present work, we specifically focus on Dy2O3and Yb2O3and use both of these materials as model systems to study, among other things, the film formation and microstructure. Our research data collectively demonstrate that (1) record pore sizes of up to 42 nm in diameter can be achieved without the need for swelling agents, (2) the nanostructure can be preserved up to 1000 °C for the heavier oxides, (3) the sizes of the optical band gaps (4.9–5.6 eV) are comparable to those reported for single crystals, (4) the sol–gel-derived materials are single phase and adopt the C-type crystal structure, and (5) the grain growth is virtually linear, with domain sizes in the range of 3–16 nm. We also show that, except for Yb2O3, all of the samples have a fiber texture and the preferred orientation is significant in Sm2O3and Lu2O3films (March parameter G2< 0.1). Overall, the synthesis parameters described in this work provide a blueprint for the preparation of thermally stable rare-earth oxide ceramics with both a mesoporous morphology and iso-oriented nanocrystalline walls.

Nail penetration tests under adiabatic conditions are proposed as a new safety test method to simulate a short circuit caused by intrusion in the worst case scenario, i.e., adiabatic conditions. The behaviors of commercially available 18650 type lithium-ion cells with two different cell chemistries, LiNi0.33Co0.33Mn0.33O2- LiCoO2blend (NCM-LCO blend) vs. graphite and LiFePO4(LFP) vs. graphite, were investigated at different states of charge (SoC). The results show a small standard deviation for the temperature and pressure measurements from five identical experiments. The detailed examination of the nail penetration experiments reveals differences in the safety properties of the cathode materials (LFP vs. NCM-LCO), separator types (PP PE PP trilayer vs. PE single layer) and electrode designs (high power vs. high energy). For both cell types, the observed cooling effect at high energy contents could be linked to an increased gas production due to the loss of electrolyte.

The title thin film electrodes with both a well‐defined mesoporous morphology and a nanocrystalline framework are synthesized by a polymer‐directed sol—gel route from a mixture of Ti(OBu)4, EtOH, AcOH, LiOAc, 2‐methoxyethanol, and a poly(ethylene‐co‐butylene)‐block‐poly(ethylene oxide) diblock copolymer as the structure‐directing agent (dip‐coating on polar substrates, 300 °C, 12 h).