Elucidating Influence of Mg‐ and Cu‐Doping on Electrochemical Properties of O3‐Nax[Fe, Mn]O2 for Na‐Ion Batteries. Issue 50 (23rd November 2020)

• Record Type: Journal Article
• Authors: Yoda, Yusuke; Kubota, Kei; Kuroki, Kazutoshi; Suzuki, Shinya; Yamanaka, Keisuke; Yaji, Toyonari; Amagasa, Shota; Yamada, Yasuhiro; Ohta, Toshiaki; Komaba, Shinichi
• Is Part Of: Small. Volume 16:Issue 50(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-23
• Subjects: anion redox -- layered oxides -- positive electrode materials -- sodium intercalation -- sodium‐ion batteries; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202006483
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Although O3‐NaFe1/2 Mn1/2 O2 delivers a large capacity of over 150 mAh g −1 in an aprotic Na cell, its moist‐air stability and cycle stability are unsatisfactory for practical use. Slightly Na‐deficient O3‐Na5/6 Fe1/2 Mn1/2 O2 (O3‐Na5/6 FeMn) and O3‐Na5/6 Fe1/3 Mn1/2 Me 1/6 O2 (Me = Mg or Cu, O3‐FeMnMe) are newly synthesized. The Cu and Mg doping provides higher moist‐air stability. O3‐Na5/6 FeMn, O3‐FeMnCu, and O3‐FeMnMg deliver first discharge capacities of 193, 176, and 196 mAh g −1, respectively. Despite partial replacement of Fe with redox inactive Mg, oxide ions in O3‐FeMnMg participate in the redox reaction more apparently than O3‐Na5/6 FeMn. X‐ray diffraction studies unveil the formation of a P‐O intergrowth phase during charging up to >4.0 V. Abstract : O3‐Na5/6 Fe1/3 Mn1/2 Mg1/6 O2 is newly synthesized which delivers a high capacity of 196 mAh g −1 and is applicable to hard carbon // O3‐Na5/6 Fe1/3 Mn1/2 Mg1/6 O2 Na‐ion cell. In addition to Mn 3+/4+ and Fe 3+/4+ redox, oxide ions participate in solid‐state redox. Furthermore, randomly stacked intergrowth phases based on the ideal OP2‐type phase reversibly appear during sodium insertion and extraction.