Chemical-mechanical effects in Ni-rich cathode materials

Yin, S, Chen, H, Chen, J, Massoudi, A, Deng, W, Gao, X, Zhang, S, Wang, Y, Lin, TW, Banks, CE ORCID: https://orcid.org/0000-0002-0756-9764, Qiao, SZ, Zou, G, Hou, H and Ji, X (2022) Chemical-mechanical effects in Ni-rich cathode materials. Chemistry of Materials, 34 (4). pp. 1509-1523. ISSN 0897-4756

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Abstract

The implementation of Ni-rich cathodes with high energy density has been critically restrained by stress corrosion. Herein, crack-free LiNbO3-coated LiNi0.88Co0.10Mn0.02O2, as theoretically predicted, demonstrates highly reversible lithiation/delithiation. Mechanically, the phase transition (H1 → H2 → H3) is significantly alleviated by the excogitation of the interfacial force invoked by the LiNbO3 coating layer, as verified by X-ray absorption spectroscopy and extended X-ray absorption near-edge structure spectroscopy. Meanwhile, the stabilities of the crystal structure are remarkably strengthened by the strong Nb-O bond activated by Nb5+ doping that is confirmed by Rietveld refinement of X-ray diffraction and differential capacitance curves. Chemically, the interface shielding effect is conducive to protecting the electrode against electrolyte corrosion along with subsequent transition-metal dissolution, ultimately rendering a faster/highly convertible lithium-ion diffusion. Greatly, the excellent electrochemical properties (74% capacity retention after 300 cycles at 2 C within 2.5-4.3 V) and structural stability (the morphology remains intact after 500 cycles at 5 C within 2.5-4.3 V) are successfully achieved. Given this, this elaborate work might inaugurate a potential avenue for rationally tuning the structure/interface evolution toward Ni-rich materials.