Simple Synchronous Dual-Modification Strategy with Zr4+Doping and CeO2 Nanowelding to Stabilize Layered Ni-Rich Cathode Materials

A Ni-rich layered oxide, one promising cathode for lithium-ion batteries (LIBs), exhibits the advantages of low cost and high capacity but suffers from rapid capacity loss due to bulk structural instability and surface side reactions. Herein, a simple synchronous dual-modification strategy with Zr4+ doping and CeO2 nanowelding is proposed to address such issues. Utilizing the migration energy difference of Zr and Ce ions in layered structures, one-step high-temperature sintering of LiNi0.8Co0.1Mn0.1O2 particles with Zr and Ce nitrate distributions enables simultaneous doping of Zr ions in the bulk and CeO2 surface modification. Therein, Zr ions in the bulk occupying the Li sites can improve the Li+ diffusion rate and stabilize the crystal structure, while CeO2 on the surface provides nanowelding between the grain boundaries and resistance to electrolyte erosion. Theoretical calculations and a series of structure/composition characterizations (i.e., neutron scattering, in situ X-ray diffraction, etc.) validated the proposed strategy and its role in stabilizing the Ni-rich cathodes. The synergistic effect of Zr4+ doping and CeO2 nanowelding enables an impressive initial capacity of 187.2 mAh g-1 (2.7-4.3 V vs Li/Li+) with 86.1% retention after 200 cycles at 1 C and rate capabilities of 146.6 and 127.3 mAh g-1 at 5 and 10 C, respectively. Upon increasing the testing temperature to 60 degrees C, the dual-modified Ni-rich cathode exhibits an initial discharge capacity of 203.5 mAh g-1 with a good retention of 80.8% after 100 cycles at 0.5 C. The present strategy utilizing the migration energy difference of metal ions to achieve synchronous bulk doping and surface modification will offer fresh insights to stabilize layered cathode materials for LIBs, which can be widely used in other kinds of batteries with various cathode materials.

Automated summary

A simple synchronous dual-modification strategy with Zr4+ doping and CeO2 nanowelding is proposed to address the capacity loss issue of Ni-rich layered oxide cathode materials in lithium-ion batteries (LIBs). The strategy utilizes the migration energy difference of Zr and Ce ions to achieve bulk doping and surface modification simultaneously. Experimental results demonstrate that the synergistic effect of Zr4+ doping and CeO2 nanowelding significantly improves the capacity and cycling performance of the cathode materials.