Electrochemical performance of Yb-doped LiFePO4/C composites as cathode materials for lithium-ion batteries

Abstract

LiFePO 4 /C and LiYb 0.02 Fe 0.98 PO 4 /C composite cathode materials were synthesized by simple solution technique. The samples were characterized by X-ray diffraction, scanning electron microscope, and thermogravimetric-differential thermal analysis. Their electrochemical properties were investigated by cyclic voltammetry, four-point probe conductivity measurements, and galvanostatic charge and discharge tests. The carbon-coated and Yb 3? -doped LiFePO4 sample exhibited an enhanced electronic conductivity of 1.9 9 10 -3 Scm -1 , and a specific discharge capacity of 146 mAhg -1 at 0.1 C. The results suggest that the improvement of the electrochemical performance can be attributed to the ytterbium doping, which facilitates the phase transformation between triphylite and heterosite during cycling, and the conductivity improvement by carbon coating.

Aligned carbon nanostructures based 3D electrodes for energy storage

“…Additionally, the electronic conductivity of LiCoO 2 has been increased by over two orders of magnitude up to about 0.5 S/cm by partial substitution of Co 3+ by Mg 2+ and compensating hole creation by West et al [91]. Besides, Hüseyin Göktepe reported the improvement of electronic conductivity of LiFePO 4 by Yb 3+ -doping up to 1.9 × 10 −3 S/cm [90].…”

“…Hence, the improvement of electronic conductivity is necessary to enhance the cell performance. As a result, many researchers have focused on improving electronic conductivity of electrode by surface coating or introducing conductive additives into the electrode materials [88,89] and improving the intrinsic electronic conductivity of active material by doping [90,91]. Carbon [88,[92][93][94], conducting polymer [95][96][97][98], and silver [99] etc.…”

ENHANCEMENT OF Li–ION BATTERY CAPACITY USING NICKEL DOPED LiFePO4 AS CATHODE MATERIAL

“…However, due to its rigid orthorhombic olivine structure, the intrinsic electronic conductivity of LFP and Li + diffusion rate is considerably low to reach full theoretical capacity during battery operation [1][2][3]. Different technical approaches have been used to overcome these drawbacks, such as: doping LFP with supervalent cations [3][4][5], reduction of particle size to nanoscale [3,6] and/or particle coating with carbon based materials [7,8].…”

“…By titanium doping, Wu L. et al [1] observed LFP capacity increase from125 to 150 Ah/kg at 0.1C discharge rate. Göktepe H. et al [8] reported the electronic conductivity of 1.9×10 -3 S/cm and capacity of 146 Ah/kg obtained by combining Yb 3+ doped and carbon coated LFP to form LiYb 0.02 Fe 0.98 PO 4 /C composite. Similarly, through the variation of lanthanum amounts doped in LFP, Cho et al [9] found out that with 1% lanthanum content (LiFe 0.99 La 0.01 PO 4 /C), the LFP structure remained unchanged, meanwhile, its capacity increased from 104 to 156 Ah/kg at 0.2C discharge rate and exhibited good cycling stability.…”

Study on LiFe1 − x Sm x PO4/C used as cathode materials for lithium-ion batteries with low Sm component

“…Zheng et al [29] thought Ni + -doping can decrease the particle size of LiFePO 4 . Hüseyin Göktepe [30] prepared LiFePO 4 /C Yb-doped with the specific capacity of 146 mAh g −1 at 0.1 C.…”