"Effects of Graphene Interface on Potassiation in a Graphene-Selenium H" by Vidushi Sharma and Dibakar Datta
 

Effects of Graphene Interface on Potassiation in a Graphene-Selenium Heterostructure Cathode for Potassium-Ion Batteries

Document Type

Article

Publication Date

8-28-2023

Abstract

Selenium (Se) cathodes are an exciting emerging high energy density storage system for potassium-ion batteries (KIB), where potassiation reactions are less understood. Here, we present an atomic-level investigation of a KxSe cathode enclosed in hexagonal lattices of carbon (C) characteristic of a layered graphene matrix and multiwalled carbon nanotubes (MW-CNTs). Microstructural changes directed by the graphene-substrate in the KxSe cathode are contrasted with those in the graphene-free cathode. Graphene’s binding affinity for long-chain polyselenides (Se3 = −2.82 eV and Se2 = −2.646 eV) at low K concentrations and ability to induce enhanced reactivity between Se and K at high K concentrations are investigated. Furthermore, intercalation voltage for graphene-enclosed KxSe cathode reaction intermediates is calculated with K2Se as the final discharged product. Our results indicate a single-step reaction near a voltage of 1.55 V between K and Se cathode. Findings in the paper suggest that operating at higher voltages (∼2 V) could result in the formation of reaction intermediates where intercalation/deintercalation of K could be a challenge, and therefore cause irreversible capacity losses in the battery. The primary issue here is the modulating favorability of graphene surface toward discharging of Se cathode due to its differential preferences for K-Se reaction intermediates. A comparison with a graphene-free cathode highlights the substantial changes a van der Waals (vdW) graphene interface can bring in the atomic structure and electrochemistry of the KxSe cathode.

Identifier

85169009650 (Scopus)

Publication Title

ACS Applied Energy Materials

External Full Text Location

https://doi.org/10.1021/acsaem.3c00989

e-ISSN

25740962

First Page

8349

Last Page

8359

Issue

16

Volume

6

Grant

1911900

Fund Ref

National Science Foundation

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