LiMPO (M = Mn, Fe) olivine phosphates are important materials for battery applications due to their stability, safety, and reliable recharge cycle. Despite continuous experimental and computational investigations, several aspects of these materials remain challenging, including conductivity dimensionality and how it maps onto Li pathways. In this work, we use a refined version of our finite temperature molecular dynamics "shooting" approach, originally designed to enhance Li hopping probability. We perform a comparative analysis of ion mobility in both materials, focused on many-particle effects. Therein, we identify main [010] diffusion channels, as well as means of interchannel couplings, in the form of Li lateral [001] hopping, which markedly impact the overall mobility efficiency as measured by self-diffusion coefficients. This clearly supports the need of many-particle approaches for reliable mechanistic investigations and for battery materials benchmarking due to the complex nature of the diffusion and transport mechanisms.
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http://dx.doi.org/10.1021/acs.jpcc.2c02013 | DOI Listing |
Phys Chem Chem Phys
February 2023
Department of Physics, Xiamen University, Xiamen 361005, China.
The olivine phosphate family has been widely utilized as cathode materials for high-performance lithium-ion batteries. However, limited energy density and poor rate performance caused by low electronic and ionic conductivities are the main obstacles that need to be overcome for their widespread application. In this work, atomic simulations have been performed to study the effects of lattice strains on the Li ion migration energy barrier in olivine phosphates LiMPO (M = Mn, Fe, Co) and (LiFePO)(LiMnPO) superlattices (SLs).
View Article and Find Full Text PDFNanomaterials (Basel)
September 2022
Faculty of Environment, Science and Economy (ESE), Renewable Energy, Electric and Electronic Engineering, University of Exeter, Penryn TR10 9FE, UK.
The rapidly increasing demand for energy storage has been consistently driving the exploration of different materials for Li-ion batteries, where the olivine lithium-metal phosphates (LiMPO) are considered one of the most potential candidates for cathode-electrode design. In this context, the work presents an extensive comparative theoretical study of the electrochemical and electrical properties of iron (Fe)-, cobalt (Co)-, manganese (Mn)-, chromium (Cr)-, and vanadium (V)-based LiMPO materials for cathode design in lithium (Li)-ion battery applications, using the density-functional-theory (DFT)-based first-principle-calculation approach. The work emphasized different material and performance aspects of the cathode design, including the cohesive energy of the material, Li-intercalation energy in olivine structure, and intrinsic diffusion coefficient across the Li channel, as well as equilibrium potential and open-circuit potential at different charge-states of Li-ion batteries.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
August 2022
Materials Discovery Group, School of Chemistry, Cardiff University, C10 3AT Cardiff, U.K.
LiMPO (M = Mn, Fe) olivine phosphates are important materials for battery applications due to their stability, safety, and reliable recharge cycle. Despite continuous experimental and computational investigations, several aspects of these materials remain challenging, including conductivity dimensionality and how it maps onto Li pathways. In this work, we use a refined version of our finite temperature molecular dynamics "shooting" approach, originally designed to enhance Li hopping probability.
View Article and Find Full Text PDFChem Sci
December 2021
Hubei Key Laboratory of Electrochemical Power Sources, College of Chemistry and Molecular Science, Wuhan University Wuhan 430072 China
The discrepancy between the trend in the diffusion coefficient of a lithium ion ( ) and that in the activation energy of ion hopping signals hidden factors determining ion transport kinetics in layered olivine phosphate materials (LiMPO). Combining density functional theory (DFT) calculations and the Landau-Zener electron transfer theory, we unravel this hidden factor to be the electronic coupling between redox centers of the host materials. The ion transport process in LiMPO is newly described as an ion-coupled electron transfer (ET) reaction, where the electronic coupling effect on is considered by incorporating the electronic transmission coefficient into the rate constant of the transfer reaction.
View Article and Find Full Text PDFInorg Chem
May 2020
Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States.
We report a detailed investigation of the long-range magnetic ordering in polycrystalline samples of LiCoPO and LiMnPO, which belong to a series of well-known olivine cathode materials LiPO (M = Mn, Fe, Co, Ni). Samples were prepared by hydrothermal and solid state methods. The magnetic susceptibility is found to be strongly field-dependent, impacting the antiferromagnetic transition temperature and the bifurcation of the FC and ZFC curves.
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