Structural study of LiFePO4–LiNiPO4 solid solutions

Tabassam, Lubna; Giuli, Gabriele; Moretti, Arianna; Nobili, Francesco; Marassi, Roberto; Minicucci, Marco; Gunnella, R.; Olivi, Luca; Cicco, Andrea Di

doi:10.1016/j.jpowsour.2012.04.036

Cited by 17 publications

(16 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At y = 0.8, the impurity-phase content is < 3%, and for y = 1, several secondary peaks (< 14%) are observed, identified mainly as Ni 3 P and Li 4 O 7 P 2 . The increasing fraction of impurity phases with increasing y is in line with results reported in literature [16,17]. Phosphide secondary phases are commonly observed for LiCoPO 4 and LiNiPO 4 samples prepared by solid state synthesis when carbon coating is applied [18][19][20].…”

Section: Methodssupporting

confidence: 91%

Local structures in mixed Li Fe1−M PO4 (M=Co, Ni) electrode materials

Jalkanen

Lindén

Karppinen

2015

Journal of Solid State Chemistry

View full text Add to dashboard Cite

Section: Methodssupporting

confidence: 91%

Local structures in mixed Li Fe1−M PO4 (M=Co, Ni) electrode materials

Jalkanen

Lindén

Karppinen

2015

Journal of Solid State Chemistry

View full text Add to dashboard Cite

“…The amount of Li-(Fe,Ni) site exchange was estimated to be very small in the Ni-substituted samples, and it is thus not predicted to significantly hinder the Li + -ion diffusion. The higher substitution levels (y = 0.6 and 0.8) show a more sloping Fe 2+ /Fe 3+ redox plateau, which may be related to a single-phase solid-solution mechanism, 8,68 as two-phase reactions produce very flat charge/discharge profiles. However, polarization effects can affect the potential profile shapes, too.…”

Section: Partially Delithiated Electrodes-the Effects Of Co and Ni Smentioning

confidence: 97%

Electrochemical Performance and Delithiation/Lithiation Characteristics of Mixed LiFe_1-_yM_yPO₄(M= Co, Ni) Electrode Materials

Jalkanen

Karppinen

2015

J. Electrochem. Soc.

View full text Add to dashboard Cite

Solid solutions of LiFe 1-y M y PO 4 /C (M = Co, Ni) within the whole substitution range (0 ≤ y ≤ 1) are systematically investigated as safe high-voltage positive electrode materials for Li-ion battery. Especially the similarities and differences between the Co-and Ni-substitution schemes are highlighted. With increasing substitution level y, the orthorhombic unit cell shrinks and the Li + -ion diffusion channel area decreases, more rapidly for the smaller-sized Ni substituent. While the Co 2+ /Co 3+ redox couple shows reversible electrochemical activity, only an initial, partial delithiation is achieved for the Ni 2+ /Ni 3+ couple at all y. However, both substitution schemes similarly affect the Fe 2+ /Fe 3+ redox couple by increasing its potential and enhancing the kinetics. Particularly, a mutual influence of Fe and Co/Ni on the delithation/lithiation characteristics is proposed: ex situ XRD analysis shows signs of a phase-composition change in the Fe 2+ /Fe 3+ region for higher y, and correspondingly, a changed Co 2+ /Co 3+ redox mechanism for lower y is indicated by cyclic voltammetry. We suggest that this behavior is related to a substitution-induced decrease in the volume change between the lithiated and delithiated phases. For the Co-substitution scheme, a composition around y ≈ 0.5 seems optimal for combining a high energy density and a kinetically beneficial, diffusional single-phase delithiation/lithiation mechanism. Li-ion batteries have been traditionally used for small, portable consumer electronics, but their utilization in large-scale applications is rapidly growing. As the size of the battery packs is increasing, the matters of safety, cost, and cycle-life become more crucial. In addition, for applications in transportation, high energy and power densities are demanded. Olivine-structured metal phosphates LiMPO 4 (M = Fe, Mn, Co, Ni) are an interesting material family to replace the layered metal oxides LiMO 2 as the positive electrode.1-4 Their safety owing to their intrinsic structural stability is very tempting for large-scale batteries. The orthorhombic olivine structure (space group Pnma) is composed of LiO 6 and MO 6 octahedra and PO 4 tetrahedra, such that Li + -ion diffusion during lithiation/delithiation takes place only in one dimension, along the b axis. 3,5The iron-based olivine LiFePO 4 is already commercially used in Li-ion batteries; it shows a theoretical capacity of 170 mAh g −1 , high safety and cycle stability, and is in addition cheap and environmentally friendly.1 The delithiation/lithiation (charge/discharge) reaction proceeds as a two-phase reaction with a varying LiFePO 4 /FePO 4 ratio, which brings about a kinetic limitation due to the single Fe valence (Fe 2+ or Fe 3+ ) in the two end-phases, resulting in low carrier density. 1,6 Additionally, the two-phase reaction pathway is restricted by nucleation and growth, when compared to a diffusional single-phase solidsolution mechanism. 7 However, narrow single-phase solid-solution regions are suggested to exist at room-tem...

show abstract

“…Incorporation of lithium bis(oxalato)borate (LiBOB) as additive in conventional electrolyte solutions enhances the electrochemical performance of LCP electrode [120]. 4 OH, cotton fibers, 1,2-propanediol and ethylene glycol [36,[143][144][145][146][147][148][149][150][151][152]. Tsai [145] produced LiNiPO 4 nanocrystals via a microemulsions method and determined that the water-to-surfactant ratio directly affects the particle size and shape.…”

Section: Lithium Mn-fe Olivinementioning

confidence: 99%

“…Mg-substituted LNP/graphitic carbon foams composite was also synthesized by the same method that shows a discharge capacity of 126 mAh g −1 at C/10 rate by substituting 0.2 Mg for Ni [151]. Modifications of the local structure and lattice parameters in LiFe 1−y Ni y PO 4 (0 < x < 1) olivine-type solid solutions have been studied by X-ray absorption spectroscopy (XAS) [152,153]. Results indicate ordering of Li in the M1 site, and of Fe and Ni in the M2 site of the olivine structure.…”

Section: Lithium Mn-fe Olivinementioning

confidence: 99%

“…Ni doping is found to induce an anisotropic shrinking of the unit cell with both Fe and Ni six-coordinated with oxygens, occupying distorted octahedral sites. LiNi 1−x Cu x PO 4 (0 < x < 0.99) samples were successfully synthesized by non-aqueous sol-gel method followed by microwave (MW) annealing were found to be electrocatalysts towards oxygen reduction which is apparently due to nanosized particles as obtained via MW annealing [152]. The solid solution LiNi x Fe 1−x PO 4 (0 < x < 1) synthesized via a solid-state reaction under Ar ambient shows lattice parameters following the Vegard's law but the formation of agglomerates reduces the specific capacity that cannot exceed 45 mAh g −1 [153].…”

Section: Lithium Mn-fe Olivinementioning

confidence: 99%

See 1 more Smart Citation