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.