DGIST Scholar: First-Principles Study on the Thermal Stability of LiNiO2 Materials Coated by Amorphous Al2O3 with Atomic Layer Thickness

Department of Energy Science and Engineering ETC 1. Journal Articles

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First-Principles Study on the Thermal Stability of LiNiO2 Materials Coated by Amorphous Al2O3 with Atomic Layer Thickness

Title: First-Principles Study on the Thermal Stability of LiNiO2 Materials Coated by Amorphous Al2O3 with Atomic Layer Thickness

Author Keywords: Li-ion battery ; first-principles calculations ; surface coating ; amorphous Al2O3 ; thermal stability

Keywords: Molecular Dynamics ; Molecular Oxygen ; Nanofiltration Membranes ; OXIDE ; Petroleum Deposits ; Phase Interfaces ; Phase Transitions ; Secondary Batteries ; STABILITY ; Surface Coating ; Surface Coatings ; Thermal Stability ; Thermodynamic Stability ; THIN-FILM ; Ab Initio Molecular Dynamics ; Aluminum ; Aluminum Coatings ; Amorphous Al2O3 ; Amorphous Materials ; Calculations ; CATHODE ; Cathodes ; Chemical Bonds ; Coated Materials ; Coatings ; Corundum Deposits ; Density Functional Theory ; DEPOSITION ; Deposits ; Electric Batteries ; Electrochemical Energy ; Electrochemical Stabilities ; Electrodes ; First-Principles Calculation ; First-Principles Calculations ; First-Principles Study ; Instability Problems ; Ions ; Li-Ion Batteries ; Li-Ion Battery ; Lithium ; Lithium-Ion Batteries

Abstract: Using first-principles calculations, we study how to enhance thermal stability of high Ni compositional cathodes in Li-ion battery application. Using the archetype material LiNiO2 (LNO), we identify that ultrathin coating of Al2O3 (0001) on LNO(012) surface, which is the Li de-/intercalation channel, substantially improves the instability problem. Density functional theory calculations indicate that the Al2O3 deposits show phase transition from the corundum-type crystalline (c-Al2O3) to amorphous (a-Al2O3) structures as the number of coating layers reaches three. Ab initio molecular dynamic simulations on the LNO(012) surface coated by a-Al2O3 (about 0.88 nm) with three atomic layers oxygen gas evolution is strongly suppressed at T = 400 K. We find that the underlying mechanism is the strong contacting force at the interface between LNO(012) and Al2O3 deposits, which, in turn, originated from highly ionic chemical bonding of Al and O at the interface. Furthermore, we identify that thermodynamic stability of the a-Al2O3 is even more enhanced with Li in the layer, implying that the protection for the LNO(012) surface by the coating layer is meaningful over the charging process. Our approach contributes to the design of innovative cathode materials with not only high-energy capacity but also long-term thermal and electrochemical stability applicable for a variety of electrochemical energy devices including Li-ion batteries. © 2015 American Chemical Society.