Dual modification of LiNi0.6Co0.2Mn0.2O2 with MgHPO4 as a high-performance cathode material for Li-ion batteries?

Energy Advances Pub Date: 2021-12-08 DOI: 10.1039/D1YA00031D

Abstract

MgHPO4 has been introduced as a reactant that interacts with LiNi0.6Co0.2Mn0.2O2 (NCM622) to achieve the dual modification of Mg2+ gradient doping and Li3PO4 surface coating. The structure, morphology, elemental distribution, and electrochemical properties of the materials are elaborately explored using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and electrochemical measurements. On the one hand, Mg2+ gradient doping stabilizes the crystal structure of the Li+/Ni2+ cation and minimizes its disorder. On the other hand, the coating of the fast lithium-ion conductor Li3PO4 not only increases the rate of lithium-ion diffusion at the electrode–electrolyte interface but also protects the cathodic material and mitigates electrolyte corrosion. The dual-modified NCM622 cathode exhibits remarkable cycling performance, retaining 89.57% of its capacity after 200 cycles at 1C from 2.8 to 4.3 V and 79.03% after 100 cycles at 3C from 2.8 to 4.5 V. Additionally, the dual-modified cathode exhibits better electrode kinetics and a reversible capacity of 119.4 mA h g?1 at 10C. This straightforward dual modification technique improves the lithium-ion diffusion kinetics at the interface while also stabilizing the internal crystal structure of Ni-rich cathode materials.

Graphical abstract: Dual modification of LiNi0.6Co0.2Mn0.2O2 with MgHPO4 as a high-performance cathode material for Li-ion batteries
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