Layered Li-rich 3d-transition-metal cathode materials, xLi 2 MnO 3 •(1−x)LiMO 2 , have increasingly triggered immense interest for their use in Li-ion batteries due to their advantages in terms of energy density. Nevertheless, poor cycle and rate performances cause limitations in practical commercial applications. We modified the material with boron bulk doping and carbon surface modification to form a B-doped layered@spinel@carbon heterostructure. Herein, B-doping can increase the lattice spacing favorable for Li + insertion/extraction and inhibit oxygen loss successfully. The spinel layer and carbon on the surface can protect the material from corrosion due to electrolyte decomposition, which can accelerate Li + and electron conduction and lessen the phase transition. The co-modified material reveals outstanding cycle and rate capability. Especially, it not only shows superior thermal stability at the high temperature of 45 °C, with a capacity retention rate of 83.3%, but also shows a higher discharge capacity of 108.9 mAh g −1 at the low temperature of −20 °C. Furthermore, the mechanism of the Li-rich cathode material with improved performance was also detected systematically. The proposed facile synthesis and co-modification of the boron-doped layered@spinel@carbon heterostructure can shed light on the design direction for cathode materials of lithium-ion batteries to solve the problem of electrochemical performance degradation caused by structural instability.

Although LiMPO4 (M = Fe, Mn) cathode materials have been widely applied in electric vehicles owing to the advantages of excellent safety, cycle stability, and low cost, poor electronic conductivity of LiMPO4 severely limits the further expansion of its applied field. Herein, the LiFe0.8Mn0.2PO4 composite with boron/phosphorus dual-doped carbon coating (LFMP@B/P–C) was fabricated by a sol–gel hydrothermal method. As a result, LFMP@B/P–C exhibits superior rate performance (97.1 mAh g–1 at 20 C) and preferable low-temperature performance (78.2 mAh g–1 at 1 C and −20 °C). It is mainly attributed to the synergistic effect of boron/phosphorus dual-doped carbon coatings, as confirmed by combined experimental characterizations with density functional theory calculations. That is, boron-doped carbon coating offers additional hole carriers, and phosphorus doping provides abundant electron carriers, making it easy for electrons to escape and enter and greatly improving the conductivity of the material. In addition, the phosphorus atom also acts as a bridge so that the carbon coating layer is tightly coated on the surface of the material. This will provide an idea for the research on the modification of cathode materials in the future.

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