Development of Wet-Li2ZrO3-Coating Process for LiNi0.8Co0.1Mn0.1O2 Cathode for All-Solid-State Batteries

Abstract

All-solid-state batteries are considered as the next-generation energy storage technology due to their potential for higher energy and power densities, as well as improved reliability and safety compared to conventional lithium-ion batteries with liquid electrolytes[1,2]. However, technical challenges remain in achieving the necessary interface stability between the cathode active material and solid electrolyte, e.g., Li6PS5Cl[3,4]. Herein, we present a facile wet coating process for achieving a uniform and conformal Li2ZrO3 coating on LiNi0.8Co0.1Mn0.1O2 cathode particles to improve the performance of thio-sulfide-based all-solid-state batteries. The coating process was based on the addition of zirconium and lithium precursors to absolute ethanol-cathode dispersion, resulting in the adsorption of ZrO2+ and Li+ species onto LiNi0.8Co0.1Mn0.1O2 particles. After evaporating the solvent, the precipitate was calcinated, whereby the effects of different precursor weight percentages, types of precursors, conditions of solvent evaporation, and calcination temperatures on the distribution, uniformity, and crystallinity of the coating layers were subject of investigation. A wide spectrum of techniques has been used to evaluate phases, structure, and microstructure of the coated cathode particles. The optimal coating thickness has been determined by testing the coated cathodes in pellet-type all-solid-state batteries, composed by a composite cathode (ratio between LiNi0.8Co0.1Mn0.1O2, Li6PS5Cl, and conductive carbon: 11:16:1), Li-In alloy as anode, and Li6PS5Cl as separator and evaluating the electrochemical performance in respect of the initial discharge capacity, capacity retention after 200 cycles, C-rate performance, and cycling stability. ASSBs containing LiNi0.8Co0.1Mn0.1O2 cathode with an optimized Li2ZrO3-coating thickness of 10 nm showed not only increased specific capacity during the initial discharge (from 125 mAh/g to 149 mAh/g) but also exhibited improved capacity retention from 83% to 98% after 200 cycles. Reference [1] Janek J, Zeier WG. A solid future for battery development. Nature Energy. 2016, 8;1(9):1-4.[2] Tatsumisago M, Nagao M, Hayashi A. Recent development of sulfide solid electrolytes and interfacial modification for all-solid-state rechargeable lithium batteries. Journal of Asian Ceramic Societies. 2013, 1;1(1):17-25.[3] Culver SP, Koerver R, Zeier WG, Janek J. On the functionality of coatings for cathode active materials in thiophosphate‐based all‐solid‐state batteries. Advanced Energy Materials. 2019, 9(24):1900626.[4] Minnmann P, Strauss F, Bielefeld A, Ruess R, Adelhelm P, Burkhardt S, Dreyer SL, Trevisanello E, Ehrenberg H, Brezesinski T, Richter FH. Designing Cathodes and Cathode Active Materials for Solid‐State Batteries. Advanced Energy Materials. 2022, 12(35):2201425. Acknowledgements DR acknowledge financial support by Austrian Federal Ministry for Digital and Economic Affairs, the National Foundation for Research, Technology and Development and the Christian Doppler Research Association (Christian Doppler Laboratory for Solid-State Batteries).