Elucidating the Role of sALD-Deposited ZrO x Coatings on the Electrochemical Performance of LiNi0.5Mn1.5O4 Cathodes

Abstract

LiNi0.5Mn1.5O4 (LNMO) is a promising high-voltage, cobalt-free cathode material but suffers from severe interfacial degradation that limits the cycling stability of LNMO/graphite cells. Here, spatial atomic layer deposition (sALD) was employed to deposit conformal nano-ZrOx coatings directly onto LNMO composite electrodes, providing a scalable approach for electrode-level interface engineering. The influence of coating thickness and substrate translation speed on electrochemical performance was systematically investigated. Increasing the ZrOx thickness improved the long-term stability of LNMO/graphite cells but increased interfacial resistance, highlighting the trade-off between interfacial protection and charge-transfer kinetics. A ZrOx thickness of 3.0 nm provided the optimum balance, extending cell end-of-life by 71% compared with pristine LNMO while maintaining good rate capability. Post-mortem X-ray fluorescence analysis revealed reduced Mn and Ni deposition on graphite anodes, consistent with suppressed cathode–anode cross-talk. Furthermore, reducing the substrate translation speed from 10 to 5 mm s–1 further increased the end-of-life of the LNMO/graphite cells by 51%. These results demonstrate that both coating thickness and sALD processing parameters are critical for developing durable, high-voltage LNMO/graphite cells.