The development of high-voltage LiCoO 2 is essential for achieving lithium-ion batteries with high volumetric energy density, however, it faces a great deal of challenges owing to materials structure and interfacial instability issues. In this work, we have developed a strategy, through heat annealing the pre-coated surface layer to in-situ form a high-voltage-stable surface coating layer, which has been demonstrated to be highly effective to improve the high-voltage cycle performances of LiCoO 2 .We discover that LiCoO 2 reacts with Li 1.5 Al 0.5 Ti 1.5 (PO 4 ) 3 (LATP) at 700 o C to form exclusively spinel phases in addition to Li 3 PO 4 , which are structurally coherent to the layered lattice of LiCoO 2 . The This article is protected by copyright. All rights reserved.3 heat annealing of the pre-coated thin layer of LATP on LiCoO 2 enables the formation of a high-quality surface coating layer. Spinel phases possess high-voltage-stable lattice structures with much weaker oxidizing ability of lattice oxygen than layered structure. Besides, the Li 3 PO 4 is a good lithium ion conductor with excellent chemical stability at high voltages. All these benefits synergistically contribute to the construction of a uniform and conformal high-voltage-stable surface layer with favorable lithium conducting kinetics at the LiCoO 2 surface. The modified LiCoO 2 shows excellent 4.6 V high-voltage cycle performance with a discharge capacity retention of 88.3% (180.3 mAh g -1 ) and 72.9% (160.9 mAh g -1 ) after 100 cycles at room temperature and 45 o C, respectively. The thermal stability of the modified electrode has been greatly enhanced as well.

Dendrite growth is one of the major problems that hinder the practical application of lithium metal electrodes in rechargeable lithium batteries. Herein, we report that the thin-film Cu3N coating can greatly suppress the lithium dendrite growth on the Cu current collector. Li|Cu and LiFePO4|Cu cells using thin-film Cu3N-modified Cu foil as electrode exhibit improved cyclic stability and low charge–discharge overpotential. A multifaceted investigation demonstrates that Cu3N can convert to Li3N/Cu nanocomposite after initial lithium plating, forming in situ a highly homogeneous conductive network. The peak-force tunneling atomic force microscopy experiments enable the direct measurement of the surface conductivity, confirming the improved distribution uniformity for the Cu3N-modified Cu. These findings suggest that the uniformity of surface electronic conductivity is an important factor for homogeneous lithium plating–stripping, and in situ formation of a nanoconductive network via conversion reaction could be an effective way to smoothen surface conductivity and thus to achieve high uniformity.

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