Insights into LiMXO₄F (M–X = Al–P and Mg–S) as Cathode Coatings for High-Performance Lithium-Ion Batteries

Abstract

Cathode coatings have received extensive attention due to their ability to delay electrochemical performance degradation in lithium-ion batteries. However, the development of cathode coatings possessing high ionic conductivity and good interfacial stability with cathode materials has proven to be a challenge. Here, we performed first-principles computational studies on the phase stability, thermodynamic stability, and ionic transport properties of LiMXO4F (M–X = Al–P and Mg–S) used as cathode coatings. We find that the candidate coatings are thermodynamically metastable and can be synthesized experimentally. The coating materials possess high oxidative stability, with the materials predicted to decompose above 4.2 V, suggesting that they have good electrochemical stability under a high-voltage cathode. In addition, the candidate coatings exhibit significant chemical stability when in contact with oxide cathodes. Finally, we have studied the Li-ion transport paths and migration barriers of LiMXO4F (M–X = Al–P and Mg–S) and calculated the low migration barriers to be 0.19 and 0.09 eV, respectively. Our findings indicate that LiMXO4F (M–X = Al–P and Mg–S) are promising cathode coatings, among which LiAlPO4F has been experimentally confirmed. The theoretical cathode coating computational methods presented here can be extended to the solid-state battery system.

Improved structure stability and performance of a LiFeSO4F cathode material for lithium-ion batteries by magnesium substitution

“…Cation-substituting is another approach to improve the electrochemical properties of the cathode material. [9][10][11] So far, Mn-, Ni-, Co-, Zn-and Ti-substituted LiFeSO 4 F products have been synthesized using hydrophobic ionic liquids or a solid state process. [12][13][14] Unfortunately, the substituted materials barely show an improvement in the electrochemical performance.…”

Additive-Derived Surface Modification of Cathodes in All-Solid-State Batteries: The Effect of Lithium Difluorophosphate- and Lithium Difluoro(oxalato)borate-Derived Coating Layers

“…Coating the cathode with a material that exhibits high sulfide-electrolyte resistance minimizes parasitic (side) reactions between cathodes and sulfide-based solid electrolytes. This technique, commonly used in LIB systems, − stabilizes the cathode–sulfide electrolyte interface. However, the effectiveness of a coating varies significantly with the properties of the coating material and coating-layer morphology. − Effective cathode coating layers should meet several criteria.…”

Reversible Assembly of Conductive Supragel Building Blocks by Metallo‐Complexes

“…Here, chemical crosslinking based on the formation of covalent bonds between two hydrogels [ 12–14 ] or physical crosslinking based on physical interactions, such as electrostatic interactions, [ 15 ] still remain the most common method of choice. Various strategies of inter‐crosslinking have been proposed, [ 11,16–30 ] they often require complex chemical modification of the precursors or gels, [ 20 ] lack stability, [ 21 ] have high costs of the reagents, [ 22,23 ] or significant modification time, [ 24 ] thereby restricting the supragels' broader applicability. As we believe that control over the information flow within supragels is crucial to unlock their full potential as smart materials, our goal is to apply an inter‐crosslinking method enabling efficient reversible inter‐crosslinking of hydrogel building blocks, that does not require complex chemical modifications of the initial components or the final hydrogel, and ensures high stability as well as the implementation of additional functionality, e.g., conductivity across building blocks.…”