Electron and Ion Transfer across Interfaces of the NASICON-Type LATP Solid Electrolyte with Electrodes in All-Solid-State Batteries: A Density Functional Theory Study via an Explicit Interface Model

Hong-Kang Tian; Randy Jalem; Bo Gao; Yuta Yamamoto; Shunsuke Muto; Miyuki Sakakura; Yasutoshi Iriyama; Yoshitaka Tateyama

doi:10.1021/acsami.0c16463

Electron and Ion Transfer across Interfaces of the NASICON-Type LATP Solid Electrolyte with Electrodes in All-Solid-State Batteries: A Density Functional Theory Study via an Explicit Interface Model

ACS Appl Mater Interfaces. 2020 Dec 9;12(49):54752-54762. doi: 10.1021/acsami.0c16463. Epub 2020 Nov 23.

Authors

Hong-Kang Tian¹, Randy Jalem^{1

2

3}, Bo Gao¹, Yuta Yamamoto⁴, Shunsuke Muto⁵, Miyuki Sakakura⁶, Yasutoshi Iriyama⁶, Yoshitaka Tateyama^{1

2}

Affiliations

¹ Center for Green Research on Energy and Environmental Materials (GREEN) and International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
² Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan.
³ PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012, Japan.
⁴ High-Voltage Electron Microscope Laboratory, Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
⁵ Advanced Measurement Technology Center, Institute of Materials and Systems for Sustainability, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
⁶ Department of Materials Design Innovation Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan.

PMID: 33226213
DOI: 10.1021/acsami.0c16463

Abstract

NASICON-type oxide Li_1+xAl_xTi_2-x(PO₄)₃ (LATP) is expected to be a promising solid electrolyte (SE) for all-solid-state batteries (ASSBs) owing to its high ion conductivity and chemical stability. However, its interface properties with electrodes on the atomic scale remain unclear, but it is crucial for rational control of the ASSBs performance. Herein, we focused on the LATP SE with x = 0.17 and investigated the electron and ion transfer behaviors at the interfaces with the Li metal negative electrode and the LiCoO₂ (LCO) positive electrode via explicit interface models and density functional theory calculations. Ti reduction was found at the LATP/Li interface. For the LATP/LCO interface, the results indicated the Li-ion transfer from LCO to LATP upon contact until a certain electric double layer is formed under equilibrium, in which LCO is partially reduced. Co-Ti exchange was also found to be favorable where the Li ion moves with Co³⁺ to LATP. We also explored the possible interfacial processes during annealing by simulating the oxygen removal effect and found that oxygen vacancy can be more easily formed in the LCO at the interface. It implies that partial Li ions move back to LCO for the local charge neutrality. We also demonstrated higher Li chemical potential around the LATP/LCO interfaces, leading to the dynamical Li-ion depletion upon charging. The calculation results and the deduced mechanisms well explain the experimental results so far and provide insights into the interfacial electron and ion transfer upon contact, during annealing, and charging.

Keywords: Li chemical potential; all-solid-state battery; atomic interface structures; cation exchange; electron transfer; first-principles calculations; oxygen vacancy; solid electrolyte.