NaCoSiO as a cathode material for sodium-ion batteries: structure, electrochemistry and diffusion pathways.

The importance of developing new low-cost and safe cathodes for large-scale sodium batteries has led to recent interest in silicate compounds. A novel cobalt orthosilicate, NaCoSiO, shows promise as a high voltage (3.3 V vs.

The influence of large cations on the electrochemical properties of tunnel-structured metal oxides.

Metal oxides with a tunnelled structure are attractive as charge storage materials for rechargeable batteries and supercapacitors, since the tunnels enable fast reversible insertion/extraction of charge carriers (for example, lithium ions). Common synthesis methods can introduce large cations such as potassium, barium and ammonium ions into the tunnels, but how these cations affect charge storage performance is not fully understood. Here, we report the role of tunnel cations in governing the electrochemical properties of electrode materials by focusing on potassium ions in α-MnO.

Atomistic Insights into the Oriented Attachment of Tunnel-Based Oxide Nanostructures.

Controlled synthesis of nanomaterials is one of the grand challenges facing materials scientists. In particular, how tunnel-based nanomaterials aggregate during synthesis while maintaining their well-aligned tunneled structure is not fully understood. Here, we describe the atomistic mechanism of oriented attachment (OA) during solution synthesis of tunneled α-MnO2 nanowires based on a combination of in situ liquid cell transmission electron microscopy (TEM), aberration-corrected scanning TEM with subangstrom spatial resolution, and first-principles calculations.

Unusual Mn coordination and redox chemistry in the high capacity borate cathode Li7Mn(BO3)3.

The recently discovered lithium-rich cathode material Li7Mn(BO3)3 has a high theoretical capacity and an unusual tetrahedral Mn(2+) coordination. Atomistic simulation and density functional theory (DFT) techniques are employed to provide insights into the defect and redox chemistry, the structural changes upon lithium extraction and the mechanisms of lithium ion diffusion. The most favourable intrinsic defects are Li/Mn anti-site pairs, where Li and Mn ions occupy interchanged positions, and Li Frenkel defects.