Hydrothermally synthesized nanostructured LiMnxFe1−xPO4 (x = 0–0.3) cathode materials with enhanced properties for lithium-ion batteries

Abstract

Nanostructured cathode materials based on Mn-doped olivine LiMnxFe1−xPO4 (x = 0, 0.1, 0.2, and 0.3) were successfully synthesized via a hydrothermal route. The field-emission scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyzed results indicated that the synthesized LiMnxFe1−xPO4 (x = 0, 0.1, 0.2, and 0.3) samples possessed a sphere-like nanostructure and a relatively homogeneous size distribution in the range of 100–200 nm. Electrochemical experiments and analysis showed that the Mn doping increased the redox potential and boosted the capacity. While the undoped olivine (LiFePO4) had a capacity of 169 mAh g−1 with a slight reduction (10%) in the initial capacity after 50 cycles (150 mAh g−1), the Mn-doped olivine samples (LiMnxFe1−xPO4) demonstrated reliable cycling tests with negligible capacity loss, reaching 151, 147, and 157 mAh g−1 for x = 0.1, 0.2, and 0.3, respectively. The results from electrochemical impedance spectroscopy (EIS) accompanied by the galvanostatic intermittent titration technique (GITT) have resulted that the Mn substitution for Fe promoted the charge transfer process and hence the rapid Li transport. These findings indicate that the LiMnxFe1−xPO4 nanostructures are promising cathode materials for lithium ion battery applications.

Preparation and Electrochemical Properties of Carbon-Coated LiMn0.6Fe0.4PO4 Cathode Material for Lithium-Ion Batteries

“…This trend is consistent with the reported in Ref. 30, which can be roughly attributed to that the Jahn-Teller distortion of Mn 3+ in LiMn x Fe 1−x PO 4 /C materials aggravates with an increase in the degree of Mn doping, resulting in a decline of the discharge capacity. 18 To meet the needs of the automotive industry, the LiMn x Fe 1−x PO 4 and LiNi x Co y Mn 1−x O 2 mixture with high energy density and low cost is considered to be a promising commercial cathode material for lithium-ion batteries.…”

Preparation of LiFe0.99Mn0.01PO4 Cathode Material with Lower Fe-Li Antisite via Wet-Lithiation Following by Tavorite-Olivine Phase Transition

“…On the other hand, 0-LFP and Mn-LFP samples (Figs. 1a and 1b) displayed a pure and well-crystallized single olivine phase with a space group of Pnma (JCPDS 81-1173), 12 indicating that Mn and carbon do not influence the phase purity of LiFePO 4 . The lattice parameters and average particle size of the 0-LFP and Mn-LFP According to literature reports, the lattice expansion was induced by the Mn substitution (radius: Mn 2+ = 0.08 nm > Fe 2+ = 0.074 nm).…”

“…The lattice parameters and average particle size of the 0-LFP and Mn-LFP According to literature reports, the lattice expansion was induced by the Mn substitution (radius: Mn 2+ = 0.08 nm > Fe 2+ = 0.074 nm). 12,34,35 The Scherrer equation (D = Kλ/β cosθ) was employed to calculate the average particle size of LFP nanoparticles, 12 with Mn-LFP observed to possess a size of 53.3 nm, while 0-LFP exhibited a size of 36.1 nm.…”

“…Mn 2+ , Mg 2+ , Co 2+ , Cu 2+ ) has also been achieved to refine the diffusivity of such systems, [8][9][10] while the aliovalent dopants (e.g., Al 3+ , Zr 4+ , Nb 5+ , Ta 5+ ) are undesired on either Li (M1) or Fe (M2) sites. 11 Trinh et al 12 established that the lithium diffusion coefficient of olivines with metal substitution are strongly depended on types of doping metals, crystalline size of olivines, preparation method and carbon coating.…”

Synchrotron-based operando X-ray diffraction and X-ray absorption spectroscopy study of LiCo0.5Fe0.5PO4 mixed d-metal olivine cathode

“…Moreover, in several works, cobalt ions were substituted with different transition metals such as Ni, Mn, and Fe, and this substitution caused significant improvement in the electronic and ionic conductivity of LiCoPO 4 , thus enhancing its electrochemical performance 15 – 19 . The improvement in the bulk conductivity is not due to antisite defects (Co or Fe on the Li site); but from the mobile polarons, and associated with lithium vacancies 20 , 21 . While the operating voltage was not noticeably lowered, the charge carrier transport in the crystal structure was improved, leading to a stabilization of the charging process and a decrease in the number of reactive species formed on the electrode surface.…”