Surface-Modified Quaternary Layered Ni-Rich Cathode Materials by Li<sub>2</sub>ZrO<sub>3</sub> for Improved Electrochemical Performance for High-Power Li-Ion Batteries
Juliya Jeyakumar, Yi–Shiuan Wu, She‐Huang Wu, Rajan Jose, Chun‐Chen Yang
Abstract
Quaternary Ni-rich layered cathodes are one of the most intriguing yet challenging next-generation cathode materials, and their high Ni content has made it difficult to obtain long-term cyclability. In this paper, we report the improved electrochemical performance of high-power long-life Ni-rich layered cathode materials (LiNi0.90Co0.04Mn0.03Al0.03O2, denoted NCMA), synthesized in a Couette–Taylor reactor, after depositing a homogeneous surface coating of Li2ZrO3 (LZO). Morphological analyses revealed that the thickness of the LZO coating was approximately 2.5 nm and spread uniformly on the NCMA surface. X-ray photoelectron spectroscopy indicated that the content of Li residues on the surface had greatly decreased after coating with LZO. The electrochemical performance of the coated samples was greater than that of the bare NCMA; in particular, the 1 wt % LZO-coated cathode material had a capacity retention of 90.2% after 100 cycles at 1C (vs 74.6% for the bare NCMA). Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and the galvanostatic intermittent titration technique (GITT) indicated that the coating agent acted as a bridge that lowered the activation energy and polarization potential for a better Li+ ion transport. The polarization potential also decreased significantly after coating with LZO, leading to improved electrochemical kinetics. Postmortem studies after long cycling confirmed that the LZO coating layer enhanced the structural stability of the cathode.