Covalency Measurements via NMR in Lithium Metal Phosphates

Wilcke, S. L.; Lee, Young Joo; Cairns, Elton J.; Reimer, Jeffrey A.

doi:10.1007/s00723-007-0032-1

Cited by 48 publications

(58 citation statements)

References 33 publications

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“…The NMR spectra of the two studies were acquired at different MAS speeds -22.5 KHz in Ref. 34 and 60 KHz in Ref. 37.…”

Section: Resultsmentioning

confidence: 99%

“…These materials, and in particular LiFePO 4 [31] and its Mn-substituted derivatives [32], are commercially relevant lithium-ion battery positive electrode (cathode) materials. Computational results from solid-state Density Functional Theory (DFT) are compared to the experimental shifts obtained for the corresponding powder samples [33,34] and a method to extract individual g-tensors in solids containing high concentration of paramagnetic centres from DFT calculations is demonstrated.…”

Section: Introductionmentioning

confidence: 99%

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DFT investigation of the effect of spin-orbit coupling on the NMR shifts in paramagnetic solids

et al. 2017

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Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for studying the structural and electronic properties of paramagnetic solids. However, the interpretation of paramagnetic NMR spectra is often challenging as a result of the interactions of unpaired electrons with the nuclear spins of interest. In this work, we extend the formalism of the paramagnetic NMR shielding in the presence of spin-orbit coupling towards solid systems with multiple paramagnetic centres. We demonstrate how the single-ion Electron Paramagnetic Resonance (EPR) g-tensor is defined and calculated in periodic paramagnetic solids. We then calculate the hyperfine tensor and the g-tensor with density functional theory (DFT) to show the validity of the presented model and we further demonstrate how these interactions can be combined to give the overall paramagnetic shielding tensor, σ s . The method is applied to a series of olivine-type LiTMPO4 materials (with TM=Mn, Fe, Co and Ni) and the corresponding 7 Li and 31 P NMR spectra are simulated. We analyse the effects of spin-orbit coupling and of the electron-nuclear magnetic interactions on the calculated NMR parameters. A detailed comparison is presented between contact and dipolar interactions across the LiTMPO4 series, in which the magnitudes and signs of the non-relativistic and relativistic components of the overall isotropic shift and shift anisotropy are computed and rationalized.

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“…The NMR spectra of the two studies were acquired at different MAS speeds -22.5 KHz in Ref. 34 and 60 KHz in Ref. 37.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

DFT investigation of the effect of spin-orbit coupling on the NMR shifts in paramagnetic solids

et al. 2017

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“…Paramagnetic interactions.-Hyperfine interactions result from the coupling between the nuclear moment of the NMR probe and the time-average of the local field due to unpaired d electrons present on neighboring paramagnetic transition metals, S z . Hyperfine interactions can induce large shifts and shift anisotropies in the order of 100-10000 ppm in the NMR spectra 109,110 and, when using high magnetic field strengths, necessitate broadband excitation NMR techniques. 111 Hyperfine interactions can either be through-space (dipolar coupling) or through-bond (Fermi contact) interactions.…”

Section: Studying Phase Transformations and Electronic Phenomena Occumentioning

confidence: 99%

“…Berthelot et al claimed that the interslab cationic distribution in P2-Na x CoO 2 results from the energy minimization between in-plane electrostatic repulsions that tend to Figure 5. [110] sections of the P2 and O2 structures. When Na is removed from the P2 structure, a sliding of adjacent MO 2 layers occurs to create Na octahedra (from trigonal prisms).…”

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confidence: 99%

Review—Manganese-Based P2-Type Transition Metal Oxides as Sodium-Ion Battery Cathode Materials

Clément

Bruce

Grey

2015

J. Electrochem. Soc.

423

388

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Sodium transition metal oxides (NaMO 2 ) with a P2 structure exhibit good Na + ion conductivity and are promising sodium-ion battery cathode materials. Manganese-based compounds have a high working potential vs. Na + /Na, and high capacity. Yet, the layered nature of these materials means that they are prone to structural rearrangements at high voltage/low Na contents, the phase transformations and Na + ion/vacancy ordering transitions resulting in capacity fade and poor reversibility. This review discusses the latest advances in the field and focuses mainly on recent work on Na y Mn 1-x M x O 2 (x, y ≤ 1, M = Ni, Mg, Li) compounds. We compare the different lithium and sodium transition metal layered oxides (P2, O3, etc.) and describe the structures and mechanisms observed on alkali (de)intercalation. The strategies used to enhance the electrochemical properties and stabilize the structural framework of sodium transition metal oxides are reviewed. We show how X-ray diffraction and 7 Li/ 23 Na solid-state Nuclear Magnetic Resonance can be combined to provide a detailed insight into the structural and electronic processes occurring upon electrochemical cycling of these materials. Why Are We Interested in Na-Ion Battery Cathodes?Together, the increasing demand for energy and the threat from Global Warming make electrical energy storage (EES) a world wide strategic priority. EES is expected to play a key role in the decarbonization of electric power sources. The two billion people worldwide not currently served by a reliable electricity supply are likely to be connected via local grids, for which EES is essential. While Li-ion batteries (LIBs) will play a role, a key challenge is to develop lower cost batteries that deliver safe, reliable storage with high cycle and calendar life. In this regard, Na-ion batteries (NIBs) are potentially important. NIBs operate in a similar fashion to LIBs, offering both advantages and disadvantages. Concerning the former, the ability to use Al instead of Cu as a current collector at the anode could substantially reduce cost. Na is also far more abundant in the Earth's crust than Li, and more widely distributed geographically. Regarding the disadvantages, the standard operating potential of Na metal is 300 mV more positive than Li metal. This generally translates into lower operating potentials for Na-ion systems, although the potential of a full cell depends on the difference in the chemical potentials of Na in the anode and cathode materials. There are considerable opportunities for scientists to develop new combinations of anode, electrolyte and cathode that are optimized for a variety of applications with different criteria such as high energy density, high power, and high operating potential. This has encouraged a rapid growth of interest in research into NIB components. Hard carbons show some promise as anodes, [1][2][3] but more must be done to improve performance. The cathode remains a major challenge and it is to this that we direct the current review. A comparative plot sho...

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“…Moreover, the diamagnetic resonance of 0.6 ppm was detected clearly on LiCoPO 4 annealed at 500°C by NMR in addition to the common observed resonance of ¹97 ppm corresponding to the lithium site in LiCoPO 4 bulk. 16 These results implied that the local distortion on Li 1¹¤ CoPO 4 annealed at 500°C associated with the co-existing of some lithium impurities would affect the decrease of the capacity. Therefore, the LiCoPO 4 annealed at 600°C was used for assembling ASS-LIB.…”

Section: Resultsmentioning

confidence: 89%

Application of LiCoPO4 Positive Electrode Material in All-Solid-State Lithium-Ion Battery

2014

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Submicron particles of high voltage LiCoPO 4 are prepared by sucrose-aided combustion synthesise as a preliminary arrangement for the construction of all-solid-sate lithium-ion battery. The obtained LiCoPO 4 was assembled with Li 2 O-Al 2 O 3 -TiO 2 -P 2 O 5 (LATP) solid electrolyte using spark plasma sintering (SPS) process in order to form enhanced electrical contacts. The reversible charge/discharge capacity of LiCoPO 4 was obtained by cyclic voltammetry with a sweep rate of 0.5 mV s −1 at 150°C. It would be due to the enhanced interfacial contact between LiCoPO 4 and LATP electrolyte without any voids, which was observed by the cross-sectional SEM images.

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Covalency Measurements via NMR in Lithium Metal Phosphates

Cited by 48 publications

References 33 publications

DFT investigation of the effect of spin-orbit coupling on the NMR shifts in paramagnetic solids

DFT investigation of the effect of spin-orbit coupling on the NMR shifts in paramagnetic solids

Review—Manganese-Based P2-Type Transition Metal Oxides as Sodium-Ion Battery Cathode Materials

Application of LiCoPO4 Positive Electrode Material in All-Solid-State Lithium-Ion Battery

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