Dynamic Electrode-Electrolyte Intermixing in Solid-State Sodium Nano-Batteries

R Blake Nuwayhid; Alexander C Kozen; Daniel M Long; Kunal Ahuja; Gary W Rubloff; Keith E Gregorczyk

doi:10.1021/acsami.2c23256

Dynamic Electrode-Electrolyte Intermixing in Solid-State Sodium Nano-Batteries

ACS Appl Mater Interfaces. 2023 May 24;15(20):24271-24283. doi: 10.1021/acsami.2c23256. Epub 2023 May 11.

Authors

R Blake Nuwayhid^{1

2}, Alexander C Kozen^{1

2}, Daniel M Long^{3

4

5}, Kunal Ahuja^{2

6}, Gary W Rubloff^{1

2}, Keith E Gregorczyk^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States.
² Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742, United States.
³ Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433, United States.
⁴ UES Inc., Beavercreek, Ohio 45432, United States.
⁵ Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87123, United States.
⁶ Department of Mechanical Engineering, University of Maryland, College Park, Maryland 20742, United States.

PMID: 37167022
DOI: 10.1021/acsami.2c23256

Abstract

Nanostructured solid-state batteries (SSBs) are poised to meet the demands of next-generation energy storage technologies by realizing performance competitive to their liquid-based counterparts while simultaneously offering improved safety and expanded form factors. Atomic layer deposition (ALD) is among the tools essential to fabricate nanostructured devices with challenging aspect ratios. Here, we report the fabrication and electrochemical testing of the first nanoscale sodium all-solid-state battery (SSB) using ALD to deposit both the V₂O₅ cathode and NaPON solid electrolyte followed by evaporation of a thin-film Na metal anode. NaPON exhibits remarkable stability against evaporated Na metal, showing no electrolyte breakdown or significant interphase formation in the voltage range of 0.05-6.0 V vs Na/Na⁺. Electrochemical analysis of the SSB suggests intermixing of the NaPON/V₂O₅ layers during fabrication, which we investigate in three ways: in situ spectroscopic ellipsometry, time-resolved X-ray photoelectron spectroscopy (XPS) depth profiling, and cross-sectional cryo-scanning transmission electron microscopy (cryo-STEM) coupled with electron energy loss spectroscopy (EELS). We characterize the interfacial reaction during the ALD NaPON deposition on V₂O₅ to be twofold: (1) reduction of V₂O₅ to VO₂ and (2) Na⁺ insertion into VO₂ to form Na_xVO₂. Despite the intermixing of NaPON-V₂O₅, we demonstrate that NaPON-coated V₂O₅ electrodes display enhanced electrochemical cycling stability in liquid-electrolyte coin cells through the formation of a stable electrolyte interphase. In all-SSBs, the Na metal evaporation process is found to intensify the intermixing reaction, resulting in the irreversible formation of mixed interphases between discrete battery layers. Despite this graded composition, the SSB can operate for over 100 charge-discharge cycles at room temperature and represents the first demonstration of a functional thin-film solid-state sodium-ion battery.

Keywords: atomic layer deposition; electrode−electrolyte interphase; energy storage; micro-batteries; sodium-ion batteries; solid-state batteries; solid-state electrolytes; thin-film batteries.