RESEARCH ARTICLE

Surface cobaltization for boosted kinetics and excellent stability of nickel-rich layered cathodes

¹ State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Key Laboratory of Two-Dimensional Materials, School of Physics and Electronics, Hunan University, Changsha 410082, China
² School of Science, Harbin Institute of Technology, Shenzhen 518055, China
³ Shenzhen Research Institute, Hunan University, Changsha 518055, China

^* Corresponding authors (emails: jzhu@hnu.edu.cn (Jian Zhu); luba2012@hnu.edu.cn (Bingan Lu))

Received: 29 March 2024
Revised: 17 May 2024
Accepted: 22 May 2024

Abstract

The feasibility of LiNi_0.6Co_0.2Mn_0.2O₂ as a primary cathode material has decreased due to the fragile cobalt (Co) supply chain and its undesirable effects on structural degradation. LiNi_0.6Mn_0.4O₂ deserves greater attention because of its high thermal and cyclic stability, coupled with low raw material and production costs. However, this material suffers from low reversible capacity and poor rate performance. Herein, we rationally design a high-performance cathode structure composed of a robust conductive protective layer, gradient Li⁺ ions conductive layer and stable bulk phase of LiNi_0.6Mn_0.4O₂ through surface cobaltization, which not only boosts the reaction kinetics of the electrode but also suppresses particle cracking and mitigates surface structural degradation. As a result, a dramatically improved rate capacity (118.7 vs 53.5 mAh g⁻¹ at 5 C) and impressive capacity retention after 300 cycles (90.4% in a full cell) at a high cutoff voltage (4.4 V) are obtained. Co-modified LiNi_0.6Mn_0.4O₂ is promising to challenge commercial position of LiNi_0.6Co_0.2Mn_0.2O₂ attributed to the accessible capacity, superior rate capacity, excellent cycle performance, good thermal stability and low cost. Our results open a door for optimizing the use of Co and the structural design of high-nickel cathodes.