Abstract
Cationic doping has been recommended as one of the most effective methods of reducing the number of trivalent manganese (Mn3+) ions that undergo a disproportionation reaction in lithium manganese oxide-based (LiMn2O4) lithium-ion batteries. However, the effect of surface doping on the major LiMn2O4 surfaces and their interactions with the electrolyte components is not yet fully understood. In this work, spin-polarised density functional theory-based calculations [DFT + U-D3 (BJ)] were employed to study the adsorption of the electrolyte components ethylene carbonate (EC) and hydrogen fluoride (HF) onto the Nb-doped major LiMn2O4 (001), (011), and (111) surfaces. During the substitution of niobium for manganese ions in the second surface layers (Nbsecond ), it was found that the (111) surface stability improves, resulting in an enhanced (111) plane on the morphology. However, replacing the first (Nbfirst ) as well as both top and sub-surface (Nbboth ) layers of Mn atoms in the slabs maintains the same stability trend as in the pure pristine surfaces. Moreover, both adsorbates greatly preferred binding to the surfaces through the Nb instead of Mn atoms, and the largest adsorption energy was calculated for EC on the LiMn2O4 (011) surface doped on the Nbsecond site and for HF on the LiMn2O4 (111) surface doped on the Nbboth site. Furthermore, the EC/HF adsorptions further enhance the stability of the Nbsecond (111) surface plane. However, minimal charge transfer was calculated for both HF and EC interacting with the pure and Nb-doped surfaces. Our findings are interesting, since exposing the (111) surface promotes the formation of a stable solid electrolyte interface (SEI), significantly reducing Mn dissolution and enhancing the adsorption of EC and HF.
| Original language | English |
|---|---|
| Article number | 090507 |
| Journal | Journal of the Electrochemical Society |
| Volume | 169 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - Sept 2022 |
Bibliographical note
Funding Information:The authors acknowledge funding from the UK Economic and Social Research Council (ESRC grant no. ES/N013867/1) and the National Research Foundation South Africa for funding of a UK-SA Newton PhD partnership programme. PEN acknowledges the financial support of the DSI-NRF South African Research Chair Initiative and NHdL acknowledges the UK Engineering and Physical Sciences Research Council (EPSRC grant EP/K009567) for funding. We acknowledge the use of the Centre for High-Performance Computing (CHPC) facility of South Africa in the completion of this work. We also appreciate the support received from DSI Energy Storage Research Development and Innovation Initiative, South Africa. This work was performed using the computational facilities of the Material Modelling Centre (MMC), University of Limpopo, the Centre for High-Performance Computing, in Cape Town, and the Supercomputing Facilities at Cardiff University operated by ARCCA on behalf of the HPC Wales and Supercomputing Wales (SCW) projects. All data created during this research are presented in this paper.
Publisher Copyright:
© 2022 The Electrochemical Society (“ECS”). Published on behalf of ECS by IOP Publishing Limited.
Funding
The authors acknowledge funding from the UK Economic and Social Research Council (ESRC grant no. ES/N013867/1) and the National Research Foundation South Africa for funding of a UK-SA Newton PhD partnership programme. PEN acknowledges the financial support of the DSI-NRF South African Research Chair Initiative and NHdL acknowledges the UK Engineering and Physical Sciences Research Council (EPSRC grant EP/K009567) for funding. We acknowledge the use of the Centre for High-Performance Computing (CHPC) facility of South Africa in the completion of this work. We also appreciate the support received from DSI Energy Storage Research Development and Innovation Initiative, South Africa. This work was performed using the computational facilities of the Material Modelling Centre (MMC), University of Limpopo, the Centre for High-Performance Computing, in Cape Town, and the Supercomputing Facilities at Cardiff University operated by ARCCA on behalf of the HPC Wales and Supercomputing Wales (SCW) projects. All data created during this research are presented in this paper.
