First-Principles Study of Microscopic Electrochemistry at the LiCoO2 Cathode/LiNbO3 Coating/β-Li3PS4 Solid Electrolyte Interfaces in an All-Solid-State Battery

Bo Gao; Randy Jalem; Yoshitaka Tateyama

doi:10.1021/acsami.0c19091

First-Principles Study of Microscopic Electrochemistry at the LiCoO₂ Cathode/LiNbO₃ Coating/β-Li₃PS₄ Solid Electrolyte Interfaces in an All-Solid-State Battery

ACS Appl Mater Interfaces. 2021 Mar 17;13(10):11765-11773. doi: 10.1021/acsami.0c19091. Epub 2021 Mar 5.

Authors

Bo Gao¹, Randy Jalem^{1

2

3}, Yoshitaka Tateyama^{1

2}

Affiliations

¹ Center for Green Research on Energy and Environmental Materials (GREEN) and International Center for Materials Nanoarchitectonics (MANA), NIMS, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
² Elements Strategy Initiative for Catalysts & Batteries, 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.

PMID: 33673737
DOI: 10.1021/acsami.0c19091

Abstract

High interfacial resistance between electrode and solid electrolyte (SE) is one of the major challenges for the commercial application of all-solid-state batteries (ASSBs), and coating at the interface is an effective way for decreasing the resistance. However, microscopic electrochemistry especially for the electrochemical potential and the distribution of Li⁺ at the interface has not been well established yet, impeding the in-depth understanding of interfacial Li⁺ transport. Herein, we have introduced a potential energy profile for Li⁺, η_Li⁺, and demonstrated that the interfacial η_Li⁺ can be evaluated from the calculated interfacial Li vacancy formation energy or the bulk vacancy formation energy and the interface band alignment. Through computational analysis of the representative LiCoO₂ cathode/LiNbO₃ coating/β-Li₃PS₄ SE interfaces using the novel interface structure prediction scheme based on the CALYPSO method, we found that η_Li⁺ at the LiCoO₂/β-Li₃PS₄ interface is highly disordered under the influence of the interface reconstruction and is rather electronic conductive. Insertion of LiNbO₃ coating can effectively decrease the preference of ion mixing. Besides, the appropriate changes in band alignments lead to a decrease of difference in the interfacial η_Li⁺ and lower resistances at the interfaces. The results provide a reliable explanation for the effectiveness of the coating layer observed experimentally. Furthermore, our study provides a guidance for the future simulation of the microscopic electrochemistry at the electrode/SE interfaces in ASSBs.

Keywords: all-solid-state battery; density functional theory; electrochemical potential; electrochemistry; solid−solid interface.