[1P01-32] Poster session

[1P28] Theoretical investigation of surface effects on the durability of MnNi oxides for Na-ion battery systems

*Kohei Tada¹, Riki Kataoka², Tomoya Ogata¹, Yukichika Kitano¹, Yasutaka Kitagawa¹ (1. The University of Osaka (Japan), 2. AIST (Japan))

Sodium-ion batteries (SIBs) are attracting attention as candidate systems for post-lithium-ion batteries. Generally, cathode materials in SIBs determine not only their potentials and capacities but also their stabilities and environmental impacts. Our previous research showed that ball-milling improve the stability of high active structure (P2-type layered structure) and generate vacancy of Ni cations, which has high environmental impacts. We have suggested three mechanisms for the positive effects by ball-milling: (1) surface energy control, (2) suppression of layer-slide, and (3) stabilisation of vacancy at nano grain boundaries. In this presentation, the mechanism (1) is mainly discussed. Specifically, the surface area exposed to the (100) plane was found to be key to enhancing the stability of the P2 structure at a high state of charge owing to the high surface energy of the (100) plane for the low active structure.

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