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Layered sodium nickel manganese oxides (NaxNiyMn1-yO2) have gained great interest as one of the positive electrode materials in sodium ion batteries towards sustainable energy storage systems. However, significant capacity fade of those materials necessities to be solved. Partial substitutions for Ni and Mn at the expense of delivered capacity have been widely suggested to address the poor cycle life, whereas relatively little investigation on particle morphology and/or surface engineering has been carried out. Herein, P3- and P2-type Na0.76Ni0.38Mn0.62O2 powders were prepared using 4 µm and 10 µm (Ni0.38Mn0.62)(OH)2 precursors to understand the influence of primary and secondary particle sizes and polytypes on their electrochemical performance in Na cells. P3-type Na0.76Ni0.38Mn0.62O2 with smaller primary particles and the absence of impurity leads to superior cyclability and rate capability than P2-type one. Besides, larger secondary particles improve cycling performance in both polytypes. Formation of microcracks is inevitable over 100 cycles, especially with the upper cut-off voltage of 4.4 V, however more severe pulverization and microcracks are shown in 4 µm P3-type Na0.76Ni0.38Mn0.62O2 compared to 10 µm P3-type Na0.76Ni0.38Mn0.62O2. The severity in prevalent microcracks, rapid growth of resistance over cycling as well as aging, and CO2 gas release upon charge to 4.4 V supports the degradation of 4 µm P3-type Na0.76Ni0.38Mn0.62O2 driven by parasitic surface reactions, causing capacity fade.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: sodium-ion batteries, P3-type, P2-type, secondary particle size, moisture sensitivity, microcracks

Date published: 2024-02-12

Publisher: American Chemical Society (ACS)

Journal:

• ACS Applied Energy Materials (ISSN: 25740962) vol. 7 issue. 3 p. 1015-1026

Funding:

• Ministry of Education, Culture, Sports, Science and Technology JPMXP 1122712807
• Ministry of Education, Culture, Sports, Science and Technology JPMJCR21O6
• Japan Society for the Promotion of Science JP20H02849
• Japan Society for the Promotion of Science JP21K14724
• Japan Society for the Promotion of Science JP21K20561
• Japan Society for the Promotion of Science JP22K14772
• Japan Society for the Promotion of Science JP23K13829

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acsaem.3c02462

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Updated at: 2025-01-08 16:30:33 +0900

Published on MDR: 2025-01-08 16:30:33 +0900