Crystal Chemistry and Ionic Conductivity of the NASICON-Related Phases in the LiNaV(PO) System.

In the present work, we studied crystal phases in the LiNaV(PO) system over a wide range of prepared by four synthesis methods: mechanochemically assisted solid-state synthesis, 'soft chemistry' sol-gel approach, chemical (CIE) and electrochemical (EIE) ion exchange starting from LiV(PO) (anti-NASICON, 2/ S.G.), and NaV(PO) (NASICON, 2/ S.

Synchrotron-based operando X-ray diffraction and X-ray absorption spectroscopy study of LiCoFePO mixed d-metal olivine cathode.

Lithium-ion batteries based on high-voltage cathode materials, such as LiCoPO, despite being promising in terms of specific power, still suffer from poor cycle life due to the lower stability of common non-aqueous electrolytes at higher voltages. One way to overcome this issue might be decreasing the working potential of the battery by doping LiCoPO by Fe, thus reducing electrolyte degradation upon cycling. However, such modification requires a deep understanding of the structural behavior of cathode material upon lithiation/delithiation.

Understanding of the Mechanism and Kinetics of the Fast Solid-State Reaction between NaF and VPO to Form NaV(PO)F.

The solid-state reaction between NaF and VPO is widely used to produce NaV(PO)F, a promising cathode material for sodium-ion batteries. In the present work, the mechanism and kinetics of the reaction between NaF and VPO were investigated, and the effect of preliminary high-energy ball milling (HEBM) was studied using time-resolved synchrotron powder X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, etc. The reaction was attributed to a "dimensional reduction" formalism; it proceeds quickly with the unilateral diffusion of Na and F ions into VPO particles as a limiting stage.

Effect of transition metal cations on the local structure and lithium transport in disordered rock-salt oxides.

Lithium-excess oxides LiTiMnO and LiNbMnO with a disordered rock-salt structure and Mn/Mn as a redox couple were compared to analyze the effect of different d metal ions on the local structure and Li ion migration. These cathode materials were obtained by mechanochemically assisted solid-state synthesis. Using XRD, Li NMR and EPR spectroscopy and transmission electron microscopy it was shown that the Mn ions are prone to form clusters, while d metal ions are evenly distributed in the crystal lattice.

Crystal structure and migration paths of alkaline ions in NaVPOF.

A sample with a nominal composition 'NaVPO4F' is prepared by mechanochemically assisted solid-state synthesis using quenching. A detailed study of its crystal and local structure is conducted by means of XRD and FTIR and solid-state 31P NMR spectroscopies in comparison with Na3V2(PO4)2F3. It is shown that the as-prepared 'NaVPO4F' has a multiphase composition, including NaVPO4F as the main phase and Na3V2(PO4)2F3 and Na2.