A Quasi‐Multinary Composite Coating on a Nickel‐Rich NCM Cathode Material for All‐Solid‐State Batteries
David Kitsche, Florian Strauss, Yushu Tang, Nikolai Bartnick, A‐Young Kim, Yuan Ma, Christian Kübel, Jürgen Janek, Torsten Brezesinski
Abstract
Abstract Inorganic solid‐state batteries are attracting significant interest as a contender to conventional liquid electrolyte‐based lithium‐ion batteries but still suffer from several limitations. The search for advanced coatings for protecting cathode materials in solid‐state batteries to achieve interfacial stability is a continuing challenge. In the present work, the surface of an industrially relevant Ni‐rich LiNi x Co y Mn z O 2 cathode material, NCM‐851005 (85 % Ni), was modified by applying a coating containing Li, Nb and Zn, aiming at a composition Li 6 ZnNb 4 O 14 , by means of sol‐gel chemistry. Detailed characterization using scanning transmission electron microscopy combined with energy‐dispersive X‐ray spectroscopy and nano‐beam electron diffraction showed that the surface layer after heating in O 2 at 500 °C contains Li 3 NbO 4 nanocrystals and Li 2 CO 3 , with Zn presumably acting as a dopant. The protective coating on the NCM‐851005 secondary particles significantly increased the cycling performance (reversible capacity, rate capability etc.) and stability of full cells using argyrodite Li 6 PS 5 Cl as solid electrolyte. Interestingly, the level of improvement is superior to that achieved with conventional LiNbO 3 coatings.