The Sodium Storage Mechanism in Tunnel‐Type Na0.44MnO2 Cathodes and the Way to Ensure Their Durable Operation. Issue 21 (16th April 2020)

• Record Type: Journal Article
• Authors: Chae, Munseok S.; Kim, Hyojeong J.; Bu, Hyeri; Lyoo, Jeyne; Attias, Ran; Dlugatch, Ben; Oliel, Matan; Gofer, Yosef; Hong, Seung‐Tae; Aurbach, Doron
• Is Part Of: Advanced energy materials. Volume 10:Issue 21(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-04-16
• Subjects: cathode surface films -- electrolyte solutions additives -- sodium intercalation -- sodium‐ion batteries -- tunnel‐type sodium manganese oxide; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202000564
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Tunnel‐type sodium manganese oxide is a promising cathode material for aqueous/nonaqueous sodium‐ion batteries, however its storage mechanism is not fully understood, in part due to the complicated sodium intercalation process. In addition, low cyclability due to manganese dissolution has limited its practical application in rechargeable batteries. Here, the intricate sodium intercalation mechanism of Na0.44 MnO2 is revealed by combination of electrochemical characterization, structure determination from powder X‐ray diffraction data, 3D bond valence difference maps, and barrier‐energy calculations of the sodium diffusion. NaI is proposed as an important electrolyte solution additive. It is shown to form a thin, beneficial, and durable cathode surface film that prevents manganese dissolution. The addition of 0.01 m NaI to electrolyte solutions based on alkyl carbonate solvents and NaClO4 greatly improves the cycling efficiency, raising the capacity retention from 86% to 96% after 600 cycles. This study determines the core aspects of the sodium intercalation mechanism in tunnel‐type sodium manganese oxide and shows how it can serve as a durable cathode material for rechargeable Na batteries. Abstract : The intricate sodium storage mechanism of Na0.44 MnO2 is revealed by combination of electrochemical characterization, structure determination from powder X‐ray diffraction data, 3D bond valence maps and barrier‐energy calculations of the sodium diffusion. In addition, NaI as an electrolyte additive is shown to form a thin, beneficial, and durable cathode surface film that prevents manganese dissolution.