Inducing Favorable Cation Antisite by Doping Halogen in Ni‐Rich Layered Cathode with Ultrahigh Stability

Abstract

The cation antisite is the most recognizable intrinsic defect type in nickel‐rich layered and olivine‐type cathode materials for lithium‐ion batteries, and important for electrochemical/thermal performance. While how to generate the favorable antisite has not been put forward, herein, by combining first‐principles calculation with neutron powder diffraction (NPD) study, a defect inducing the favorable antisite mechanism is proposed to improve cathode stability, that is, halogen substitution facilitates the neighboring Li and Ni atoms to exchange their sites, forming a more stable local octahedron of halide (LOSH). According to the mechanism, it is demonstrated by NPD that F‐doping not only induces the antisite formation in layered LiNi 0.85 Co 0.075 Mn 0.075 O 2 (LNCM), but also increases the antisite concentration linearly. F substitution (1%) induces 5.7% antisite, and it displays an excellent capacity retention of 94% at 1 C for 200 cycles under 25 °C, outstanding high temperature cyclability (153.4 mAh·g –1 at 1 C for 120 cycles under 55 °C). The onset decomposition temperature increases by 48 °C. The ultrahigh cycling/thermal stability is attributed to the stronger LOSH, and it keeps the structural integrity after long cycling and develops an electrostatic repulsion force between oxygen layers to increase the lattice parameter c , which benefits Li‐ion migration.

Challenges and Strategies to Advance High‐Energy Nickel‐Rich Layered Lithium Transition Metal Oxide Cathodes for Harsh Operation

“…[110] More recently, Li et al reported that doping halogen in Ni-rich cathodes could induce favorable cation antisite formation, and hence significantly improve the electrochemical and thermal stability. [111] First-principles calculation revealed that the halogen substitution could facilitate the exchange of the adjacent Li + and Ni 2+ to from a lower total energy and more stable local octahedron structure, which is due to the stronger bond strength of X-Li than X-Ni. As shown in Figure 24a, the Figure 23.…”

“…a) The effect of F, Cl, Br, and I substitution on the calculated antisite defect formation energies, the inset models are LOSH. [111] b) Schematic illustration of the preparation process of AS-LNCM, indicating that the LiF compounds migrate into the particles of Ni 0.85 Co 0.075 Mn 0.075 (OH) 3 and react with each other to facilitate O substituted by F; further sintering with LiOH generates the favorable antisite in the most stable LOSH to stabilize layered LNCM. [111] c) Room-temperature cycling performance over 200 cycles at a rate of 1C.…”

“…[111] b) Schematic illustration of the preparation process of AS-LNCM, indicating that the LiF compounds migrate into the particles of Ni 0.85 Co 0.075 Mn 0.075 (OH) 3 and react with each other to facilitate O substituted by F; further sintering with LiOH generates the favorable antisite in the most stable LOSH to stabilize layered LNCM. [111] c) Room-temperature cycling performance over 200 cycles at a rate of 1C. [111] d) C80 profiles of delithiated PRI, 5.7% AS, and 8.2% AS cathodes that were charged to 4.3 V in advanced.…”

“…[111] c) Room-temperature cycling performance over 200 cycles at a rate of 1C. [111] d) C80 profiles of delithiated PRI, 5.7% AS, and 8.2% AS cathodes that were charged to 4.3 V in advanced. Reproduced under the terms of the CC-BY license.…”

“…Reproduced under the terms of the CC-BY license. [111] Copyright 2019, The Authors, published by Wiley-VCH.…”