Understanding migration barriers for monovalent ion insertion in transition metal oxide and phosphate based cathode materials: A DFT study

Aksyonov, Dmitry A.; Fedotov, Stanislav S.; Stevenson, Keith J.; Zhugayevych, Andriy

doi:10.1016/j.commatsci.2018.07.057

Cited by 65 publications

(45 citation statements)

References 61 publications

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“…Generally, the PBE flavor of the exchange‐correlation potential overestimates experimental lattice constants of phosphates by 1–2 % . Considering a similar behavior of PBE for the LiNaCoPO 4 F phases, the cell parameters for Co 2+ in a high spin state indeed exceed the experimental values by 0–2 %, confirming that Co 2+ is in a high spin state, which was also previously validated by magnetic susceptibility measurements for 3D‐LiNaCoPO 4 F …”

Section: Resultssupporting

confidence: 77%

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Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F

et al. 2019

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Co-containing fluoride-phosphates are of interest in sense of delivering high electrode potentials and attractive specific energy values as positive electrode materials for rechargeable batteries. In this paper we report on a new Co-based fluoride-phosphate, LiNaCoPO 4 F, with a layered structure (2D), which was Rietveld-refined based on X-ray powder diffraction data [P2 1 /c, a = 6.83881(4) Å, b = 11.23323(5) Å, c = 5.07654(2) Å, = 90.3517(5)°, V = 389.982(3) Å 3 ] and validated by electron diffraction and high-resolution scanning transmission electron microscopy. The differential scanning calorimetry measurements revealed that 2D-LiNaCoPO 4 F forms in a narrow temperature range of 520-530°C and irreversibly converts to the known 3D-LiNaCoPO 4 F modification (Pnma) above 530°C. The non- [a] 4365 carbon-coated 2D-LiNaCoPO 4 F shows reversible electrochemical activity in Li-ion cell in the potential range of 3.0-4.9 V vs. Li/Li + with an average potential of ≈ 4.5 V and in Na-ion cell in the range of 3.0-4.5 V vs. Na/Na + exhibiting a plateau profile centered around 4.2 V, in agreement with the calculated potentials by density functional theory. The energy barriers for both Li + and Na + migration in 2D-LiNaCoPO 4 F amount to 0.15 eV along the [001] direction rendering 2D-LiNaCoPO 4 F as a viable electrode material for high-power Li-and Na-ion rechargeable batteries. The discovery and stabilization of the 2D-LiNaCoPO 4 F polymorph indicates that temperature influence on the synthesis of A 2 MPO 4 F fluoride-phosphates needs more careful examination with perspective to unveil new structures. trode potential to much higher values in comparison to oxides. Moreover, a better ionic transport is expected owing to a lower affinity of alkali metals towards fluoride than oxide anions. A much richer structural diversity of fluoride-phosphates offers manifold options for tuning the electrochemical properties. [4] Among fluoride-phosphates, the A 2 MPO 4 F (A = Li, Na; M = Mn, Fe, Co, Ni) family provides one of the largest playgrounds for searching new cathode materials. [5] From the electrochemical standpoint, this class also regains interest due to a theoretical possibility of multi-electron redox transitions enabling reversible de/intercalation of more than one alkali ion per transition metal center.The wide structural variety of A 2 MPO 4 F is primarily originated from multiple options in playing with the chemical composition of the cation sublattice. Depending on the nature of the A and M metals, MO 4 F 2 octahedra (key building blocks) constitute various types of linkage: from corner-sharing to facesharing and their combinations. Since A and M sites can be populated by more than one element type, altering their average ionic radius by substitutions might also influence the preferable MO 4 F 2 connectivity thus preserving a specific structural type for new chemical compositions or even giving rise to new structures.Corner-shared MO 4 F 2 octahedra are only characteristic to Na 2 MnPO 4 F [6,7] and its limited solid solu...

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Section: Resultssupporting

confidence: 77%

“…The migration barriers for Li and Na vacancies are calculated using DFT without U method. It was shown in our previous paper, that employment of Hubbard U correction has only minor influence on migration barriers, yet significantly worsens convergence of the wave function …”

Section: Resultsmentioning

confidence: 82%

Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F

et al. 2019

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“…A comparison of KTiPO 4 F and closely-related LiTiPO 4 F with the tavorite structure shows that in the case of KTiPO 4 F the average potential of K + extraction is~0.4 V higher than that of Li removal from LiTiPO 4 F, which is quite rare given that K + intercalation potentials are usually lower for the same chemical compositions 59 . Moreover, in KTiPO 4 F a stable phase at x = 0.5 is formed resulting in a pronounced step of the redox potential.…”

Section: Discussionmentioning

confidence: 98%

Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential

et al. 2020

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The rapid progress in mass-market applications of metal-ion batteries intensifies the development of economically feasible electrode materials based on earth-abundant elements. Here, we report on a record-breaking titanium-based positive electrode material, KTiPO 4 F, exhibiting a superior electrode potential of 3.6 V in a potassium-ion cell, which is extraordinarily high for titanium redox transitions. We hypothesize that such an unexpectedly major boost of the electrode potential benefits from the synergy of the cumulative inductive effect of two anions and charge/vacancy ordering. Carbon-coated electrode materials display no capacity fading when cycled at 5C rate for 100 cycles, which coupled with extremely low energy barriers for potassium-ion migration of 0.2 eV anticipates high-power applications. Our contribution shows that the titanium redox activity traditionally considered as "reducing" can be upshifted to near-4V electrode potentials thus providing a playground to design sustainable and cost-effective titanium-containing positive electrode materials with promising electrochemical characteristics.

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“…Density functional theory (DFT) [10] was used for the first-principles calculations in this work. The Vienna ab initio simulation package (VASP) [11] and the high-throughput python-based package SIMAN [12] were attracted for this purpose. The exchange-correlation energy was evaluated by the generalized gradient approximation (GGA) within Perdew-Burke-Ernzerhof (PBE) functional [13].…”

Section: Methodsmentioning

confidence: 99%

Influence of the Mo10Ni3C3B phase on the hardness and fracture toughness of Mo-Ni-C-B cermet: experimental and theoretical study

et al. 2020

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The high productivity of the cutting material is fully determined by its properties, especially the structure and phase composition. A whole range of materials with different physical and mechanical properties can be obtained by controlling these parameters for alloys of the same system. Cermets are materials that combine the high temperature resistance and hardness of ceramics and ductility of metals. Cermets based on the Mo-NiB system are promising materials in applications to cutting processing. Earlier, in this system doped with carbon, a new κ-phase Mo 10 Ni 3 C 3 B with hexagonal P63 / mmc crystal structure was detected. We obtained the decreasing of hardness and comparable values of the fracture toughness of Mo 2 NiB 2-Ni cermets due to the formation of Mo 10 Ni 3 C 3 B phase. To understand the effect of the Mo 10 Ni 3 C 3 B phase on the mechanical properties of the cermet, first-principles calculations were applied to investigate the elastic, electronic, and thermodynamic properties of this phase. Its mechanical and anisotropic properties were calculated based on the obtained elastic constants. Additionally, for a better understanding of the nature of interatomic bonding, an analysis of the electron localization function (ELF), calculated from first principles, was performed. We found that the Mo 10 Ni 3 C 3 B phase had a 42 % lower hardness and increased ductility compared to the Mo 2 NiB 2 boride, which is expressed in the value of the bulk modulus-shear modulus ratio above the brittleviscous transition. As follows from the results of the ELF analysis, a possible reason for this is the more isotropic nature of interatomic bonds, which indicates their higher degree of metallicity.

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Understanding migration barriers for monovalent ion insertion in transition metal oxide and phosphate based cathode materials: A DFT study

Cited by 65 publications

References 61 publications

Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F

Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F

Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential

Influence of the Mo10Ni3C3B phase on the hardness and fracture toughness of Mo-Ni-C-B cermet: experimental and theoretical study

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Understanding migration barriers for monovalent ion insertion in transition metal oxide and phosphate based cathode materials: A DFT study

Cited by 65 publications

References 61 publications

Tuning the Crystal Structure of A2CoPO4F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO4F

Tuning the Crystal Structure of A2CoPO4F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO4F

Titanium-based potassium-ion battery positive electrode with extraordinarily high redox potential

Influence of the Mo10Ni3C3B phase on the hardness and fracture toughness of Mo-Ni-C-B cermet: experimental and theoretical study

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Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F

Tuning the Crystal Structure of A₂CoPO₄F (A = Li, Na) Fluoride‐Phosphates: A New Layered Polymorph of LiNaCoPO₄F