Quantum mechanics

Catalysis

Engineering

Lithium (medication)

Oxide

Transmission electron microscopy

Electrochemistry

Metallurgy

Materials science

Chromatography

Cathode

Layer (electronics)

Density functional theory

Endocrinology

Transition metal

Electron energy loss spectroscopy

Biochemistry

Chemical engineering

Physical chemistry

Physics

Nanotechnology

Doping

Surface modification

Computational chemistry

Composite material

Analytical Chemistry (journal)

Scanning transmission electron microscopy

Medicine

Chemistry

Scanning electron microscope

Electrode

Surface layer

Optoelectronics

ACS Applied Materials & Interfaces

Li-rich layer-structured oxides are considered promising cathode materials for their specific capacities above 250 mAh·g-1. However, the drawbacks such as poor rate performance, fast capacity fading, and the continuous transition metal (TM) migration into the Li layer hinder their commercial applications. To address these issues, surface doping of Ti and Zr was conducted to the Li- and Mn-rich layered oxide (LMR), Li1.2Mn0.54Ni0.13Co0.13O2. The drop of the average discharge potentials of the Ti- and Zr-doped LMR was reduced by 593 and 346 mV in 100 cycles, respectively. With aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy, we clarified that Ti4+ and Zr4+ ions are located near the surface of the material, anchor the surface oxygen, and stabilize the LMR structure. The difference in the strengths of the Ti-O and Zr-O bonds and the doping-resultant electronic structures were determined with density functional theory (DFT) calculations and soft X-ray absorption spectroscopy (SXAS), responsible for the electrochemical performance of surface-doped materials. These findings verify our modification strategies to enhance the cycling performances of the promising LMR cathode materials.

Feasibility to Improve the Stability of Lithium-Rich Layered Oxides by Surface Doping