Surface enrichment and diffusion enabling gradient-doping and coating of Ni-rich cathode toward Li-ion batteries

Abstract

Critical barriers to layered Ni-rich cathode commercialisation include their rapid capacity fading and thermal runaway from crystal disintegration and their interfacial instability. Structure combines surface modification is the ultimate choice to overcome these. Here, a synchronous gradient Al-doped and LiAlO2-coated LiNi0.9Co0.1O2 cathode is designed and prepared by using an oxalate-assisted deposition and subsequent thermally driven diffusion method. Theoretical calculations, in situ X-ray diffraction results and finite-element simulation verify that Al3+ moves to the tetrahedral interstices prior to Ni2+ that eliminates the Li/Ni disorder and internal structure stress. The Li+-conductive LiAlO2 skin prevents electrolyte penetration of the boundaries and reduces side reactions. These help the Ni-rich cathode maintain a 97.4% cycle performance after 100 cycles, and a rapid charging ability of 127.7 mAh g−1 at 20 C. A 3.5-Ah pouch cell with the cathode and graphite anode showed more than a 500-long cycle life with only a 5.6% capacity loss.

An Open‐Ended Ni3S2–Co9S8 Heterostructures Nanocage Anode with Enhanced Reaction Kinetics for Superior Potassium‐Ion Batteries

“…The mechanical and thermal coupling module of COMSOL finite element simulation was used to simulate the volume change and stress distribution of electrode material during the charge and discharge process. [ 54 ] The color of the two models changed from blue to red, which represented the increased stress. The maximum and minimum stresses (Figure 4g) of the Ni‐Co‐S nanocube (4.51 kPa and 48.7 Pa) outweigh that of the Ni‐Co‐S nanocage (2.01 kPa and 14.6 Pa), and the nonuniform stress distribution of Ni‐Co‐S nanocube model is observed.…”

High‐Energy Ni‐Rich Cathode Materials for Long‐Range and Long‐Life Electric Vehicles

“…[ 18,26–30,32,33 ] Furthermore, a reduction in volume deformation and internal stress inside the particle via Al doping can enhance the structural integrity and robustness of cathode. [ 30,34,35 ]…”

“…[18,[26][27][28][29][30]32,33] Furthermore, a reduction in volume deformation and internal stress inside the particle via Al doping can enhance the structural integrity and robustness of cathode. [30,34,35] In addition to microcracking, the time during which highly reactive Ni 4+ ions are exposed to the electrolyte when the cathode is in a highly charged state also affects the deterioration of the cathode. Although the exposure time is not Li-ion batteries (LIBs) in electric vehicles (EVs) are usually operated intermittently and maintained at high states of charge (SoCs) for long periods.…”

Surface Coupling between Mechanical and Electric Fields Empowering Ni‐Rich Cathodes with Superior Cyclabilities for Lithium‐Ion Batteries

“…[12][13][14] The higher the Ni content is, the more serious degradation of microcracks will be, especially when the Ni content exceeds 80%. [15] To enhance the structural stability and electrochemical performances of Ni-rich cathodes, various strategies including in situ/ex situ coating, [16,17] heteroatom doping, [18] microstructure design, [19] grain boundary engineering, [20] and single-crystal synthesis [21] have been widely investigated, wherein surface coating is regarded as an effective approach due to their multifunctions in protecting active material from direct contact with the electrolyte and suppressing the generation of microcracks. [15] However, the coating layers are generally found apt to fall away from bulk Ni-rich material under repeated cycling due to weak interaction, lattice mismatch, and dramatic anisotropic lattice contraction along the crystallographic c-axis.…”