Effect of Concentrated Electrolyte on Aqueous Sodium-ion Battery with Sodium Manganese Hexacyanoferrate Cathode

Kosuke Nakamoto, Ryo Sakamoto, Masato Ito, Ayuko Kitajou, Shigeto Okada

Research output: Contribution to journalArticle

Abstract

From the viewpoint of the cost and safety, aqueous sodium-ion batteries are attractive candidate for large-scale energy storage. Although the operating voltage range of the aqueous battery is theoretically limited to 1.23 V by the electrochemical decomposition of water, the voltage restriction is a little bit eased in real aqueous battery system by the charge/discharge overvoltage. Effect of the concentrated electrolyte on the operation voltage was studied in aqueous Na-ion battery with Na<sub>2</sub>MnFe(CN)<sub>6</sub> hexacyanoferrates cathode and NaTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> NASICON-type anode, in order to increase the discharge voltage. According to the cyclic voltammetry, the electrochemical window of diluted 1 mol kg<sup>−1</sup> NaClO<sub>4</sub> aqueous electrolyte is only 1.9 V, whereas the corresponding electrochemical window of concentrated 17 mol kg<sup>−1</sup> NaClO<sub>4</sub> aqueous electrolyte is widen to 2.8 V. This wide electrochemical window of the concentrated aqueous electrolyte allows the Na<sub>2</sub>MnFe(CN)<sub>6</sub>//NaTi<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> aqueous sodium-ion system to work reversibly. By contrast, the framework of Na<sub>2</sub>MnFe(CN)<sub>6</sub> cathode was destroyed by the hydroxide anion generated in diluted 1 mol kg<sup>−1</sup> electrolyte.
Original languageEnglish
Pages (from-to)179-185
Number of pages7
JournalElectrochemistry
Volume85
Issue number4
DOIs
Publication statusPublished - 2017

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