Sodium/Lithium-Ion Transfer Reaction at the Interface between Low-Crystallized Carbon Nanosphere Electrodes and Organic Electrolytes

Yasuyuki Kondo; Tomokazu Fukutsuka; Yuko Yokoyama; Yuto Miyahara; Kohei Miyazaki; Takeshi Abe

doi:10.1021/acsomega.1c01751

Sodium/Lithium-Ion Transfer Reaction at the Interface between Low-Crystallized Carbon Nanosphere Electrodes and Organic Electrolytes

ACS Omega. 2021 Jul 13;6(29):18737-18744. doi: 10.1021/acsomega.1c01751. eCollection 2021 Jul 27.

Authors

Yasuyuki Kondo¹, Tomokazu Fukutsuka², Yuko Yokoyama³, Yuto Miyahara¹, Kohei Miyazaki^{1

4}, Takeshi Abe^{1

4}

Affiliations

¹ Graduate School of Engineering, Kyoto University, Nishikyo-ku, 615-8510 Kyoto, Japan.
² Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, 464-8603 Nagoya, Japan.
³ Office of Society-Academia Collaboration for Innovation, Kyoto University, Nishikyo-ku, 615-8510 Kyoto, Japan.
⁴ Element Strategy Initiative for Catalysts & Batteries, Kyoto University, Nishikyo-ku, 615-8246 Kyoto, Japan.

Abstract

Carbon nanosphere (CNS) electrodes are the candidate of sodium-ion battery (SIB) negative electrodes with small internal resistances due to their small particle sizes. Electrochemical properties of low-crystallized CNS electrodes in dilute and concentrated sodium bis(trifluoromethanesulfonyl) amide/ethylene carbonate + dimethyl carbonate (NaTFSA/EC + DMC) were first investigated. From the cyclic voltammograms, both lithium ion and sodium ion can reversibly insert into/from CNSs in all of the electrolytes used here. The cycling stability of CNSs in concentrated electrolytes was better than that in dilute electrolytes for the SIB system. The interfacial charge-transfer resistances at the interface between CNSs and organic electrolytes were evaluated using electrochemical impedance spectroscopy. In the Nyquist plots, the semicircles at the middle-frequency region were assigned to the parallel circuits of charge-transfer resistances and capacitances. The interfacial sodium-ion transfer resistances in concentrated organic electrolytes were much smaller than those in dilute electrolytes, and the rate capability of CNS electrodes in sodium salt-concentrated electrolytes might be better than in dilute electrolytes, suggesting that CNSs with concentrated electrolytes are the candidate of SIB negative electrode materials with high rate capability. The calculated activation energies of interfacial sodium-ion transfer were dependent on electrolyte compositions and similar to those of interfacial lithium-ion transfer.