Quantum‐Chemical Study of the FeNCN Conversion‐Reaction Mechanism in Lithium‐ and Sodium‐Ion Batteries

Abstract

We report a computational study on 3d transition‐metal (Cr, Mn, Fe, and Co) carbodiimides in Li‐ and Na‐ion batteries. The obtained cell voltages semi‐quantitatively fit the experiments, highlighting the practicality of PBE+U as an approach for modeling the conversion‐reaction mechanism of the FeNCN archetype with lithium and sodium. Also, the calculated voltage profiles agree satisfactorily with experiment both for full (Li‐ion battery) and partial (Na‐ion battery) discharge, even though experimental atomistic knowledge is missing up to now. Moreover, we rationalize the structural preference of intermediate ternaries and their characteristic lowering in the voltage profile using chemical‐bonding and Mulliken‐charge analysis. The formation of such ternary intermediates for the lithiation of FeNCN and the contribution of at least one ternary intermediate is also confirmed experimentally. This theoretical approach, aided by experimental findings, supports the atomistic exploration of electrode materials governed by conversion reactions.

LOBSTER: Local orbital projections, atomic charges, and chemical‐bonding analysis from projector‐augmented‐wave‐based density‐functional theory

“…Recent development has also added two major features, namely atomic charges and related populations directly from the wavefunction as well as the -dependent COHP. The former is useful for examining ionic bonding in suchlike (or polar) compounds, for example simple salts, Zintl phases, intermetallics, thermoelectrics, or even phase-change materials, [22][23] [23], [37]- [39] whereas the latter serves useful for detailed band-wise and -point-wise chemical bonding analysis. Although the memory usage for the LOBSTER calculation is around 2.6 times more than in case of the Bader calculation, the LOBSTER calculation is around 6 times faster, so that in summary the LOBSTER calculation has a 2.3 times lower resource consumption.…”

LOBSTER: Local Orbital Projections, Atomic Charges, and Chemical Bonding Analysis from Projector-Augmented-Wave-Based DFT

“…Recent development has also added two major features, namely atomic charges and related populations directly from the wavefunction as well as the 𝒌-dependent COHP. The former is useful for examining ionic bonding in suchlike (or polar) compounds, for example simple salts, Zintl phases, intermetallics, thermoelectrics, or even phase-change materials, [22][23] [23], [37]- [39] whereas the latter serves useful for detailed band-wise and 𝒌-point-wise chemical bonding analysis.…”

Robust Electrodes for Flexible Energy Storage Devices Based on Bimetallic Encapsulated Core–Multishell Structures

“…The rising demand for flexible electronics has been driving the pursuit of flexible batteries with high bending‐ or folding tolerance. [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ] To fabricate flexible electrodes, one of the most promising strategies is to grow the active materials in situ onto various self‐standing and flexible carbon‐ or metal‐based substrates, such as carbon cloth, graphene, nickel foam, and etc. [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ] However, the current flexible electrode configurations are still facing some limitations.…”