Unraveling the Role of Fluorinated Alkyl Carbonate Additives in Improving Cathode Performance in Sodium-Ion Batteries

Amey Nimkar; Netanel Shpigel; Fyodor Malchik; Shaul Bublil; Tianju Fan; Tirupathi Rao Penki; Merav Nadav Tsubery; Doron Aurbach

doi:10.1021/acsami.1c03844

Unraveling the Role of Fluorinated Alkyl Carbonate Additives in Improving Cathode Performance in Sodium-Ion Batteries

ACS Appl Mater Interfaces. 2021 Oct 6;13(39):46478-46487. doi: 10.1021/acsami.1c03844. Epub 2021 Sep 26.

Authors

Amey Nimkar¹, Netanel Shpigel¹, Fyodor Malchik¹, Shaul Bublil¹, Tianju Fan¹, Tirupathi Rao Penki¹, Merav Nadav Tsubery¹, Doron Aurbach¹

Affiliation

¹ Department of Chemistry, Bar-Ilan University, Ramat Gan 5290002, Israel.

PMID: 34569238
DOI: 10.1021/acsami.1c03844

Abstract

A key issue in the development of sustainable Na-ion batteries (NIBs) is the stability of the electrolyte solution and its ability to form effective passivation layers on both cathode and anode. In this regard, the use of fluorine-based additives is considered a promising direction for improving electrode performance. Fluoroethylene carbonate (FEC) and trans-difluoroethylene carbonate (DFEC) were demonstrated as additives or cosolvents that form effective passivating surface films in Li-ion batteries. Their effect is evaluated for the first time with cathodes in NIBs. By application of systematic electrochemical and postmortem investigations, the role of fluorinated additives in the good performance of Na_0.44MnO₂ (NMO) cathodes was deciphered. Despite the significant improvement in the performance of Li-ion cells enabled by the use of FEC and FEC + DFEC, the highest stability for NIBs was observed when only FEC was used as an additive. Mechanistic insights and analytical characterizations were carried out to shed light on the inferior effect of FEC + DFEC in NIBs, in contrast to its positive effect on the stability of Li-ion batteries.

Keywords: Na-ion electrolytes; Na-ion electrolytes additives; cathode electrolyte interface (CEI); fluoroethylene carbonate (FEC); sodium-ion batteries (NIBs); trans-difluoroethylene carbonate (DFEC).