The key to development of high-voltage P2-type Na 0.66 Ni 0.33 Mn 0.67 O 2 is the modification methods that can effectively improve its electrochemical reversibility. Herein, a doping-integrated coating strategy based on zinc element is proposed to modify P2-type Na 0.66 Ni 0.33 Mn 0.67 O 2 , which can be achieved by a facile one-step solid-state reaction. The formation mechanism of Na 0.66 Ni 0.26 Zn 0.07 Mn 0.67 O 2 @0.06ZnO (NNZM@ 0.06ZnO) is investigated, revealing that the spinel and P3 intermediate phases appear prior to the formation of the P2 phase. Ni 2+ can be preferentially incorporated into the P2 structure in competition with Zn 2+ at high temperature, resulting in a uniform enrichment of ZnO on the surface. A small amount of Zn 2+ doping significantly suppresses the Na + /vacancy ordering effect and improves the structural reversibility. Furthermore, the electrolyte decomposition is effectively reduced because of the presence of the ZnO coating layer, leading to the formation of a thin cathode electrolyte interphase film that is favorable to fast Na + diffusion. In virtue of the Zn 2+ doping and in situ formed ZnO coating, NNZM@0.06ZnO exhibits excellent cycling stability with a capacity retention of 83.7% after 100 cycles at 100 mA g −1 and rate performance with a discharge capacity of 56.4 mAh g −1 at 2000 mA g −1 , which significantly outperforms the uncoated Na 0.66 Ni 0.26 Zn 0.07 Mn 0.67 O 2 and the Na 0.66 Ni 0.26 Zn 0.07 Mn 0.67 O 2 /0.06ZnO with the coating layer introduced by mechanical milling. This work provides a new strategy to design high-performance cathode materials for sodium-ion batteries.

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A dynamic stiffness method is presented for the vibrations of plate structures that are reinforced by eccentric stiffeners. The model incorporates both out-of-plane and in-plane deformations of the plates and the stiffeners. Based on the relationship between the forces and displacements along the common edges of the plate or beam elements, the dynamic stiffness formulae for the plate and the beam elements are derived, respectively. The globally assembled dynamic stiffness matrix is then obtained using the finite element method so that the dynamics of built-up stiffened plates can be readily addressed by using the present method. Compared to the conventional finite element model, the dynamic stiffness model can provide very accurate solutions using only one element over each uniform plate and beam member, regardless of its geometry.

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