One of the major hurdles of Ni‐rich cathode materials Li1+x(NixCozMnz)wO2, y > 0.5 for lithium‐ion batteries is their low cycling stability especially for compositions with Ni ≥ 60%, which suffer from severe capacity fading and impedance increase during cycling at elevated temperatures (e.g., 45 °C). Two promising surface and structural modifications of these materials to alleviate the above drawback are (1) coatings by electrochemically inert inorganic compounds (e.g., ZrO2) or (2) lattice doping by cations like Zr4+, Al3+, Mg2+, etc. This paper demonstrates the enhanced electrochemical behavior of Ni‐rich material LiNi0.8Co0.1Mn0.1O2 (NCM811) coated with a thin ZrO2 layer. The coating is produced by an easy and scalable wet chemical approach followed by annealing the material at ≥700 °C under oxygen that results in Zr doping. It is established that some ZrO2 remains even after annealing at ≥800 °C as a surface layer on NCM811. The main finding of this work is the enhanced cycling stability and lower impedance of the coated/doped NCM811 that can be attributed to a synergetic effect of the ZrO2 coating in combination with a zirconium doping.

Ni-rich materials of layered structure LiNi x Co y Mn z O2, x > 0.5, are promising candidates as cathodes in high-energy-density Li-ion batteries for electric vehicles. The structural and cycling stability of Ni-rich cathodes can be remarkably improved by doping with a small amount of extrinsic multivalent cations. In this study, we examine development of a fast screening methodology for doping LiNi0.8Co0.1Mn0.1O2 with cations Mg2+, Al3+, Si4+, Ti4+, Zr4+, and Ta5+ by a “top-down” approach. The cathode material is coated by a precursor layer that contains the dopant, which then is introduced into the particles by diffusion during heat treatment at elevated temperatures. The methodology described herein can be applied to Ni-rich cathode materials and allows relatively easy and prompt identification of the most promising dopants. Then further optimization work can lead to development of high-capacity stable cathode materials. The present study marks Ta5+ cations as very promising dopants for Ni-rich NCM cathodes.

The precise quantification of the pyroelectric coefficient p is indispensable for the characterization of pyroelectric materials and the development of pyroelectric-based devices, such as radiation sensors or energy harvesters. A summary of the variety of techniques to measure p is given in the present review. It provides a classification after the thermal excitation and an outline of capabilities and drawbacks of the individual techniques. The main selection criteria are: the possibility to separate different contributions to the pyroelectric coefficient, to exclude thermally stimulated currents, the capability to measure p locally, and the requirement for metallic electrodes. This overview should enable the reader to choose the technique best suited for specific samples.

No abstract