Revealing the Reaction Mechanism of Sodium Selenide Confined within a Single-Walled Carbon Nanotube: Implications for Na-Se Batteries

Liang Wang; Xingming Zhang; Lei Deng; Jianfeng Tang; Huiqiu Deng; Wangyu Hu; Zhixiao Liu

doi:10.1021/acsami.8b18555

Revealing the Reaction Mechanism of Sodium Selenide Confined within a Single-Walled Carbon Nanotube: Implications for Na-Se Batteries

ACS Appl Mater Interfaces. 2019 Feb 6;11(5):4995-5002. doi: 10.1021/acsami.8b18555. Epub 2019 Jan 28.

Authors

Liang Wang¹, Xingming Zhang¹, Lei Deng¹, Jianfeng Tang¹, Huiqiu Deng, Wangyu Hu, Zhixiao Liu

Affiliation

¹ College of Science , Hunan Agricultural University , Changsha 410128 , China.

PMID: 30648387
DOI: 10.1021/acsami.8b18555

Abstract

The sodium-selenium (Na-Se) battery is a competitive candidate as the practical next-generation energy storage device. A Na₁₆Se₈ cluster confined within a (10, 10) single-walled carbon nanotube is constructed to reveal the nanoconfinement effect on the reaction mechanism of the Na-Se battery cathode. It is found that the nanoconfinement can enhance the electronic conductivity of Na _x≥12Se₈ nanostructures because itinerant electrons appear under this condition. During desodiation, polyselenide chains grow longer and the intermediate products become insulators for transferring electrons. However, hole polarons have the potential to act as charge carriers in Na _x≤10Se₈ nanostructures. The open-circuit voltage profile is plotted, and the voltage window is 1.67 ≤ U ≤ 1 V. After the first charge cycle, the cathode cannot discharge to Na₁₆Se₈, but the reversible specific capacity can still arrive at 302 mA h/g of the cathode composite.

Keywords: Na−Se battery; ab initio molecular dynamics; conductivity; density functional theory computation; nanoconfinement; polaron; reaction mechanism.