Dual-Site Doping of Cu²⁺ Enables High Voltage Stability and Rate Performance of Single-Crystal LiNi_0.5Co_0.2Mn_0.3O₂ for Li-Ion Batteries

Abstract

LiNi x Co y Mn 1−x−y O 2 (NCM) undergoes severe lattice distortion and capacity decay during charging and discharging at high voltages, affecting its cycle life. Here, dual-site doping of Cu 2+ singlecrystal LiNi 0.5 Co 0.2 Mn 0.3 O 2 (SC-NCM523) was prepared by a moltensalt-assisted method. Cu 2+ is doped into the manganese (Mn) and lithium (Li) sites, which inhibits the occurrence of cation mixing while acting as a pillar to broaden and stabilize the channels for Li + transport, and it enables high voltage stability and rate performance of the material simultaneously. The sample has a discharge capacity of 190.6 mAh g −1 in the first cycle at 0.1 C (1 C = 200 mA g −1 ) at a high cutoff voltage of 4.5 V and a capacity retention rate of 82.2% after 200 cycles at 1 C. Meanwhile, the capacity retention rate is up to 77.0% after 250 cycles at a current density of 5 C. This work is a guideline for the subsequent study of stabilizing the ontological structure of single-crystal cathode materials.

Review on Oxygen Release Mechanism and Modification Strategy of Nickel-Rich NCM Cathode Materials for Lithium-Ion Batteries: Recent Advances and Future Directions

“…(4) The joint use of multiple regulation strategies is encouraged, and the complementary advantages between different methods can regulate the oxygen precipitation phenomenon of nickel-rich NCM cathode materials more effectively. For example, Cu doping into single-crystal NCM cathode materials has accomplished the combination of particle monocrystallization and cation-doping methods, combining the high-temperature and high-voltage resistance properties of single-crystal materials with the advantages of Cu doping to hinder cation mixing and discharging and preparing cathode materials with high performance . Therefore, the joint use of different modulation strategies should be continuously explored.…”