Effect of Na substitution on P2−NaxMn2/3Ni1/3O2 cathodes for Na-ion batteries: A DFT study of structural stability, ion mobility and local charge compensation.
Year: 2026
Type: preprint
Abstract: Layered oxides emerge as promising materials as cathode in sodium ion batteries due to the possibility to avoid critical metals and the direct industrial transferability in lithium-ion battery factories. A key point is that the layered structure can host a wide range of cations, enabling the substitution as a strategy to improve key factors such as structural stability, electronic conductivity, ion mobility, etc. For that, it is important to determine how the different substituents can affect these factors, to then mitigate side reactions and improve the desired mechanisms. In the present work, the effect of the co-interlayering ions on the open circuit voltage, structural stability, cation mobility, and electronic structure has been investigated for P2−Na x Mn 2/3 Ni 1/3 O 2 cathodes through Density Functional Theory. Calculated substitution thermodynamics indicate that P2 − Na x Mn 2/3 Ni 1/3 O 2 (x = 2/3, 1/8) can accommodate K + , Ca 2+ , Mg 2+ , and Zn 2+ at the Na site. Ab initio molecular dynamics simulations reveal that all dopants preserve the structural integrity of the layered framework while inducing distinct local dynamical responses, with Mg and Zn producing the most rigid local environments and K the highest lattice flexibility. CI-NEB calculations show that K facilitates the Na-ion hopping, and Ca preserve it with Na-ion migration barriers comparable to those of the pristine material, whereas Mg and Zn significantly increase the activation energy for Na intersite-hopping. Electronic structure analysis reveals a markedly different behavior between isovalent and aliovalent substitutions, with divalent dopants enhancing oxygen participation in charge compensation and locally promoting Mn 3+ -like electronic configurations at high Na contents. These results provide atomistic insight into how Na-site chemistry governs the balance between ionic transport, electronic structure, and structural stability, offering practical guidelines for the design of high-performance layered sodium-ion cathodes.
Source: ChemRxiv
Author: German Lener
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7213552736