First Principles Study on Ta₃N₅:Ti₃O₃N₂ Solid Solution As a Water-Splitting Photocatalyst

In this paper, we propose the new Ta₃N₅:Ti₃O₃N₂ solid solution as a promising water-splitting photocatalyst. Using first principles computations, we study the phase stability, band gap, and band edge positions of the solid solution. The results suggest that the solid solution can likely be synthesized, and has a band gap lower than both its end members. The minimal band gap may be around 2.0 eV for a composition around 50%:50%, indicating that good efficiency under solar illumination may be achieved. In addition, the CB and VB of the solid solution are predicted to be bracketing the water redox levels, so the photocatalysis process is energetically favorable and bias voltage may not be required

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Dioscorea sativa

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

Synthesis, Computed Stability, and Crystal Structure of a New Family of Inorganic Compounds: Carbonophosphates

<i>Ab initio</i>-based high-throughput computing and screening are now being used to search and predict new functional materials and novel compounds. However, systematic experimental validation on the predictions remains highly challenging, yet desired. Careful comparison between computational predictions and experimental results is sparse in the literature. Here we report on a systematic experimental validation on previously presented computational predictions of a novel alkali carbonophosphate family of compounds. We report the successful hydrothermal synthesis and structural characterization of multiple sodium carbonophosphates. The experimental conditions for formation of the carbonophosphates and the computational results are compared and discussed. We also demonstrate topotactic chemical de-sodiation of one of the compounds, indicating the potential use of this novel class of compounds as Li⁺ or Na⁺ insertion electrodes

First Principles Study of the Li₁₀GeP₂S₁₂ Lithium Super Ionic Conductor Material

First Principles Study of the Li₁₀GeP₂S₁₂ Lithium Super Ionic Conductor Materia

First-Principles Simulation of the (Li–Ni–Vacancy)O Phase Diagram and Its Relevance for the Surface Phases in Ni-Rich Li-Ion Cathode Materials

Despite several reports on the surface phase transformations from a layered to a disordered spinel and a rock-salt structure at the surface of the Ni-rich cathodes, the precise structures and compositions of these surface phases are unknown. The phenomenon, in itself, is complex and involves the participation of several contributing factors. Of these factors, transition metal (TM) ion migration toward the interior of the particle and hence formation of TM-densified surface layers, triggered by oxygen loss, is thermodynamically probable. Here, we simulate the thermodynamic phase equilibria as a function of TM ion content in the cathode material in the context of lithium nickel oxides, using a combined approach of first-principles density functional calculations, the cluster expansion method, and grand canonical Monte Carlo simulations. We developed a unified lattice Hamiltonian that accommodates not only rock-salt like structures but also topologically different spinel-like structures. Also, our model provides a foundation to investigate metastable cation compositions and kinetics of the phase transformations. Our investigations predict the existence of several Ni-rich phases that were, to date, unknown in the scientific literature. Our simulated phase diagrams at finite temperature show a very low solubility range of the prototype spinel phase. We find a partially disordered spinel-like phase with far greater solubility that is expected to show very different Li diffusivity compared to that of the prototype spinel structure

Understanding the Effect of Cation Disorder on the Voltage Profile of Lithium Transition-Metal Oxides

Cation disorder is a phenomenon that is becoming increasingly important for the design of high-energy lithium transition metal oxide cathodes (LiMO₂) for Li-ion batteries. Disordered Li-excess rocksalts have recently been shown to achieve high reversible capacity, while <i>in operando</i> cation disorder has been observed in a large class of ordered compounds. The voltage slope (dVdxLi) is a critical quantity for the design of cation-disordered rocksalts, as it controls the Li capacity accessible at voltages below the stability limit of the electrolyte (∼4.5–4.7 V). In this study, we develop a lattice model based on first principles to understand and quantify the voltage slope of cation-disordered LiMO₂. We show that cation disorder increases the voltage slope of Li transition metal oxides by creating a statistical distribution of transition metal environments around Li sites, as well as by allowing Li occupation of high-voltage tetrahedral sites. We further demonstrate that the voltage slope increase upon disorder is generally smaller for high-voltage transition metals than for low-voltage transition metals due to a more effective screening of Li–M interactions by oxygen electrons. Short-range order in practical disordered compounds is found to further mitigate the voltage slope increase upon disorder. Finally, our analysis shows that the additional high-voltage tetrahedral capacity induced by disorder is smaller in Li-excess compounds than in stoichiometric LiMO₂ compounds