Defective layered Mn-based cathode materials with excellent performance via ion exchange for Li-ion batteries

Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electro-chemical activity and Coulombic efficiency. The annealing temperature of the Na precursors was impor-tant to control the P3-P2 phase transition, which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange. The O3-Li0.78[Li0.25Fe0.075Mn0.675]Od cath-ode made from a P3-type precursor calcined at 700 degrees C was analyzed using X-ray photoelectron spectrom-etry and electron paramagnetic resonance. The results showed that the presence of abundant trivalent manganese and defects resulted in a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%. Afterward, galvanostatic intermittent titration was performed to examine the Li+ ion dif-fusion coefficients, which affected the reversible capacity. First principles calculations suggested that the charge redistribution induced by oxygen vacancies (OVs) greatly affected the local Mn coordination envi-ronment and enhanced the structural activity. Moreover, the Li-deficient cathode was a perfect match for the pre-lithiation anode, providing a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in the commercial application.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

Defective layered Mn-based materials were synthesized through Li/Na ion exchange to enhance their electrochemical activity and Coulombic efficiency. The annealing temperature of the Na precursors played a crucial role in controlling the P3-P2 phase transition and determining the structure and electrochemical characteristics of the final products. The analysis of the O3-Li0.78[Li0.25Fe0.075Mn0.675]Od cathode, prepared from a P3-type precursor calcined at 700 degrees C, using X-ray photoelectron spectroscopy and electron paramagnetic resonance revealed the presence of abundant trivalent manganese and defects, leading to a discharge capacity of 230 mAh/g with an initial Coulombic efficiency of about 109%. Galvanostatic intermittent titration experiments were conducted to study the Li+ ion diffusion coefficients and their effect on reversible capacity. First principles calculations suggested that the charge redistribution induced by oxygen vacancies greatly influenced the local Mn coordination environment and enhanced the structural activity. Furthermore, the Li-deficient cathode paired with a pre-lithiated anode provided a novel approach to improve the initial Coulombic efficiency and activity of Mn-based materials in commercial applications.