Improving the lithium-ion diffusion and electrical conductivity of LiFePO4 cathode material by doping magnesium and multi-walled carbon nanotubes

Al-Samet M. A. M. M., BURGAZ E.

JOURNAL OF ALLOYS AND COMPOUNDS, cilt.947, 2023 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 947
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1016/j.jallcom.2023.169680
  • Dergi Adı: JOURNAL OF ALLOYS AND COMPOUNDS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Chemical Abstracts Core, Communication Abstracts, INSPEC, Metadex, Public Affairs Index, Civil Engineering Abstracts
  • Anahtar Kelimeler: Cathode material, Lithium iron phosphate, Multi -walled carbon nanotube, Hydrothermal method, Magnesium doping, ELECTROCHEMICAL PERFORMANCE, PHOSPHO-OLIVINES, MICROSPHERES, MORPHOLOGY, COMPOSITE, DEFECTS
  • Ondokuz Mayıs Üniversitesi Adresli: Evet

Özet

This paper reports a co-modification approach to improve both electronic conductivity and lithium-ion diffusion of lithium iron phosphate (LiFePO4) via doping magnesium (Mg2+) and multi-walled carbon na-notubes (MWCNTs). A series of LiFe1-xMgxPO4 composites consisting of various amounts of MWCNTs were synthesized by using a facile hydrothermal method which involves an in-situ MWCNTs embedding process. The structure and morphology of prepared composites were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance was tested via cyclic voltammetry (CV), electrochemical impedance spec-troscopy (EIS) and galvanostatic charge/discharge tests. All composites exhibit good crystallinity without any impurity phases. Besides, a slight shrinkage in the crystal lattice was observed after Mg2+ doping. Mg2+ is uniformly dispersed in the composites in which the formation of a three-dimensional conductive net-work enhances electronic conductivity and lithium-ion diffusion especially at high current densities. Among LiFe1-xMgxPO4/yMWNT composites, LiFe0.98Mg0.02PO4 with 1.5 wt% MWCNTs displays the highest electro-chemical performance, offering a discharge capacity of 142 mA h g-1 at 0.1 C and exhibiting a good rate capability with a capacity of 120 mA h g-1 at a high rate of 2 C and a stable long cycle life (94.5 % capacity retention over 150 cycles). The co-modified composite cathode displays high discharge capacity, good rate capability, and excellent cycling stability compared to pure LiFePO4, rendering the co-modification approach a promising strategy for the preparation of high-performance electrode materials.(c) 2023 Elsevier B.V. All rights reserved.