Lithium-rich layered oxide (LLO) cathode materials are considered to be one of the most promising next-generation candidates of cathode materials for lithium-ion batteries due to their high specific capacity. However, some inherent defects of LLOs hinder their practical application due to the oxygen loss and structure collapse resulting from intrinsic anion and cation redox reactions, such as poor cycle stability, sluggish Li+ kinetics, and voltage decay. Herein, we put forward a facile synergistic strategy to respond to these shortcomings of LLOs via dual-site doping with cerium (Ce) and boron (B) ions. The doped Ce ions occupy the octahedral sites, which not only enlarge the cell volume but also stabilize the layered framework and introduce abundant oxygen vacancies for LLOs, while B ions occupy the tetrahedral sites in the lattice, which block the migration path of transition metal (TM) ions and reduce the oxygen loss using the strong B–O bond. Based on this dual-site doping effect, after 100 cycles at 1 C, the dual-site doped materials exhibit excellent structural stability with a capacity retention of 91.15% (vs 75.12%) and also greatly suppress the voltage decay in LLOs with a voltage retention of 93.60% (vs 87.83%).

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Lithium (Li) anode has been considered to be one of the most promising candidates for energy storage systems due to its high theoretical capacity. However, the side reaction between Li-metal and electrolyte and its safety concerns are inevitable obstacles for the commercial applications of Li-metal batteries (LMBs). The cycling stability of commercial electrolyte, high-concentration electrolyte (HCE), and localized high-concentration electrolyte (LHCE) in LMBs are studied in this work. Furthermore, 2-fluoropyridine (2-FP) additive is used to significantly enhance the cycling stability of Li-metal in LHCE that contains triethyl phosphate (TEP) and bis­(2,2,2-triflfluoroethyl) ether (BTFE). The most stable cycle performance (about 2100 h) of Li||Li cell and the highest coulombic efficiency (98.82%) in the Li||Cu cell can be obtained in the system of LHCE + 2-FP (1.2 M LiFSI + TEP/BTFE + 0.01 M 2-FP). Li||LiFePO4 cell with LHCE + 2-FP exhibits the highest initial discharge capacity of 149.14 mAh g–1 and the most excellent capacity retention rate of 98.52% after 455 cycles at 1C. Moreover, the system of LHCE + 2-FP can also invest Li||LiFePO4 cell with the best rate capacity.

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