Enhanced electrochemical properties of potassium-doped lithium-rich oxide@carbon as cathode material for lithium-ion batteries

Comparative impact of surface and bulk fluoride anion doping on the electrochemical performance of co-free Li-rich Mn-based layered cathodes

Li-rich Mn-based (LMR) layered oxides are considered promising cathode materials for high energy-density Li-ion batteries. Nevertheless, challenges such as irreversible oxygen loss at the surface during the initial charge, alteration of the bulk structure, and poor rate performance impede their path to commercialisation. Most modification methods focus on specific layers, making the overall impact of modifications at various depths on the properties of materials unclear. This research presents an approach by using doping to adjust both surface and bulk properties; the materials with surface and bulk fluoride anion doping are synthesised to explore the connection between doping depth, structural and electrochemical stability. The surface-doped material significantly improves the initial Coulombic efficiency (ICE) from 77.85% to 85.12% and limits phase transitions, yet it does not enhance rate performance. Conversely, doping in bulk stands out by improving both rate performance and cyclic stability: it increases the specific discharge capacity by around 60 mAh g-1 and enhances capacity retention from 57.69% to 82.26% after 300 cycles at 5C. These results highlight a notable dependence of material properties on depth, providing essential insights into the mechanisms of surface and bulk modifications.

A nano-truncated Ni/La doped manganese spinel material for high rate performance and long cycle life lithium-ion batteries

A nano-truncated octahedral LiNi0.08La0.01Mn1.91O4 cathode material with {111} and {100} crystal planes achieves capacity retention of 89.0% after 1000 cycles at 10C.

Turning commercial MnO2 (≥85 wt%) into high-crystallized K+-doped LiMn2O4 cathode with superior structural stability by a low-temperature molten salt method

The obtainment of low-cost, easily prepared and high-powered LiMn₂O₄ is the key to achieve its wide application in various electronic devices. In this work, a mild and easily scaled molten salt method (KCl@LiCl) is utilized to convert commercial MnO₂ to the high-performance LiMn₂O₄. At the same reaction temperature, the molten salt method leads to the formation of K⁺-doped LiMn₂O₄ with higher crystallinity compared to the conventional solid state method, which contributes to the improved inner charge transfer. The Li₃PO₄ protective layer is coated on the surface of K⁺-doped LiMn₂O₄ to elevate the interfacial stability and the Li⁺ transfer on interface. Thus, the optimized electrode shows a higher specific discharge capacity (103/60 mAh g^-1 at 0.02/2 A g^-1) and a longer cyclic life (80 mAh g^-1 after 500 cycles at 0.5 A g^-1) compared to those of LiMn₂O₄ by solid state method (49/2 mAh g^-1 at 0.02/2 A g^-1 and 20 mAh g^-1 after 500 cycles at 0.5 A g^-1).