Ni-rich Li­(Ni1–x–y Co x Mn y )­O2-based cathodes still suffer from low cycling stability, which arises from capacity fading and impedance rise due to parasitic side reactions at the interface. Surface coatings have shown promising results in stabilizing the cathode surface and improving the cycling stability. However, a comprehensive understanding on the beneficial effect of the coating is still missing. In this paper, we used a solution-based technique to coat Ni-rich Li­(Ni0.70Co0.15Mn0.15)­O2 with a thin Al2O3 layer followed by post-annealing at 600 °C. Electrochemical characterization shows a drastic improvement of the cathode’s cycling stability due to the coating. After post-annealing, the cycling stability is even further improved, accompanied with its C-rate performance. Structural characterization confirms that annealing results in the formation of an amorphous Al2O3/LiAlO2 coating layer, which exhibits increased lithium-ion conductivity compared to the Al2O3 coating. More importantly, temperature-dependent impedance measurements reveal that the coatings do not affect the activation energy of the charge transport, which guarantees a sufficient electronic conductivity between the secondary NCM particles in the cathode. Thus, the Al2O3/LiAlO2 layer not only inhibits direct contact between electrode and electrolyte, preventing side reactions and stabilizes the performance, but also facilitates conductive pathways for lithium ions while preserving the electronic connectivity between cathode’s particles, leading to a low interfacial resistance and excellent rate capability. The results show the importance of providing a sufficiently high electrical conductivity accompanied with low activation energies in coating layers for both ions and electrons, which needs to be considered in design strategies for next-generation lithium-ion batteries.

Ordered mesoporous metal oxides with a high specific surface area, tailored porosity and engineered interfaces are promising materials for electrochemical applications. Especially the method of evaporation-induced self-assembly allows the formation...

The physicochemical properties of thin metal oxide layers strongly depend on the layer thickness and thus differ significantly from their bulk counterpart. In this work, we present the growth of defined thin layers of CeO 2 within mesostructured ZrO 2 thin films using atomic layer deposition (ALD). The prepared films consist of a cubic ordered arrangement of 15 nm spherical mesopores induced by the used diblock copolymer poly(isobutylene)-block-poly(ethylene oxide) (PIB 50 -b-PEO 45 ), which allows studying the growth process and the successful coating of the interior pore surfaces via the combination of scanning electron microscopy (SEM), time-of-flight mass spectrometry (ToF-SIMS), and laser ellipsometry. These methods prove the CeO 2 layer growth and impregnation of the pores up to 100 ALD cycles, at which the interconnecting channels between the mesopore layers are filled completely impeding further transport of the gaseous CeO 2 precursors. X-ray photoelectron spectroscopy (XPS) and diffractometry (XRD) measurements point out the increased amount of Ce 3+ after a low number of ALD cycles and show the presence of cubic CeO 2 with increasing amount of ALD cycles, respectively. Impedance spectroscopic investigation further proves the formation of a continuous CeO 2 path through the entire porous network of the insulating ZrO 2 film and shows a strong influence of the layer thickness on the conductivity. All in all, our work presents the preparation of novel hybrid CeO 2 /ZrO 2 model systems, which enable us to tailor their physicochemical properties by changing the thickness of the active oxide layer, and promises improvements for their use as catalysts in oxidation reactions such as the HCl oxidation reaction or as a threeway catalytic converter in automotives.

Porous yttria-stabilized zirconia (YSZ) thin films were prepared by pulsed laser deposition to investigate the influence of specific surface area on the electrical and protonic transport properties.