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The Li-rich cathode material for long cycle performance and long-term storage performance is a challenge for next-generation lithium-ion batteries due to the rapid capacity degradation over cycling and the formation of residual lithium on the surface during long-term storage. Herein, an elevated performance of Li1.2Mn0.54Ni0.13Co0.13O2 materials via CeO2 inlay is reported, which was prepared from Li1.2Mn0.54Ni0.13Co0.13O2 by sol-gel inlay with CeO2. It was proved by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy that cerium oxide cladding not only covered the surface of the material but also diffused into the interior of the material change crystal structure. Cerium oxide on the cladding not only reduces the material's contact with water and carbon dioxide in the air, but also prevents the material from being corroded by electrolyte during electrochemical test. The position of the transition metal atom is replaced Ce atoms, which increases the unit cell volume and the stability of the Li-rich material during the cycling. The results show that the storage property and the electrochemical cycling property of the material have been improved obviously. The CeO2 inlaid lithium rich material discharged 204.6 mAh/g for the first time at the current of 1C, and 164.4 mAh/g after 150 charge and discharge cycles with corresponding capacity retention rate of 80.35%, compared with the retention rate of 57.26% for pristine Li-rich material capacity. After being stored in humid air for 40 days, the CeO2 inlaid lithium-rich material showed better electrochemical performance than the pristine one. It is powerfully demonstrated that the CeO2 inlay strategy here holds huge promise for surface modification of electrode materials for lithium-ion batteries.

Different content of Ti4+ has been successfully doped into the lattice sites of Cr3+ in NaCrO2 by the two step solid-state reaction. The analysis results of crystal structure demonstrate that the interslab (NaO2) spacing is increased with Ti doping content, which contributes to widening the sodium ion migration channel and then facilitating the rapid (de)intercalation capability of sodium ions. During charge-discharge processes, these O3-Na1-xCr1-xTixO2 (x = 0.03, 0.05, 0.1) layered oxides exhibit delayed O3-P3 phase transition and increased average discharge voltage due to stronger Ti-O bond relative to Cr-O bond. In particular, the Na0.95Cr0.95Ti0.05O2 shows the optimal electrochemical performance which releases a discharge specific capacity of 96.7 mAh g−1 at 1 C (100 mA g−1) with 80.1% capacity retention after 800 cycles. Even under the high rate of 30 C, it can deliver a discharge specific capacity of 67 mAh g−1.